Entomologists study insects, including what they look like and how they react and behave, and also the environment they like to live in.
(Where's Part 1? You just watched it above in the "What is Biology" section!) Scientists don’t just classify things based on how they look. For example, alligators and crocodiles both look similar, and how they look actually depends on which part of the world they came from.
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Dissection in biology provides a hands-on education above and beyond reading a textbook. By seeing, touching and exploring different organs, muscles and tissues inside an animal and seeing how they work together allows you to really understand your own body and appreciate the amazing world around us. And it's not hard - you can dissect a clam right at home using this inexpensive clam specimen with a dissection guide and simple dissection tools! Many doctors, surgeons and veterinarians report that their first fascination with the body started with a biology dissection class.
Materials:
- Fresh clam (in shell)
- Dissection tools
- Clam diagrams
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Click here to go to part 17:Earthworm Dissection
Entomologists study insects, including what they look like and how they react and behave, and also the environment they like to live in.
Scientists don’t just classify things based on how they look. For example, alligators and crocodiles both look similar, and how they look actually depends on which part of the world they came from.
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Click here to download Homework Problem Set #12
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Let’s get more practice with Henry’s Law, partial pressures, mole fraction, and weight percent with these sample calculations:
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Osmosis is how cells allow water to pass through in and out of the cell through a special membrane using a bit of chemistry. Here is how they do it…
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Let’s do some sample calculations for the energy of a system that include enthalpy and specific heat.
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Click here to download the Homework Problem Set #7.
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Click here to for Homework Problem Set #10
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This is an introduction to the microscope, and we’re going to not only how to use a microscope but also cover the basics of optics, slide preparation, and why we can see things that are invisible to the naked eye. Microscopes are basically two lenses put together to make things appear larger.
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Supercooling a liquid is a really neat way of keeping the liquid a liquid below the freezing temperature. Normally, when you decrease the temperature of water below 32oF, it turns into ice. But if you do it gently and slowly enough, it will stay a liquid, albeit a really cold one!
In nature, you’ll find supercooled water drops in freezing rain and also inside cumulus clouds. Pilots that fly through these clouds need to pay careful attention, as ice can instantly form on the instrument ports causing the instruments to fail. More dangerous is when it forms on the wings, changing the shape of the wing and causing the wing to stop producing lift. Most planes have de-icing capabilities, but the pilot still needs to turn it on.
We’re going to supercool water, and then disturb it to watch the crystals grow right before our eyes! While we’re only going to supercool it a couple of degrees, scientists can actually supercool water to below -43oF!
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Click here to go to next lesson on Colloids and Polymers
This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn, too! Learn about the world of rocks, crystals, gems, fossils, and minerals by moving beyond just looking at pretty stones and really being able to identify, test, and classify samples and specimens you come across using techniques that real field experts use. While most people might think of a rock as being fun to climb or toss into a pond, you will now be able to see the special meaning behind the naturally occurring material that is made out of minerals by understanding how the minerals are joined together, what their crystalline structure is like, and much more.
Materials:
- Geology Field Trip in a Bag
- Worksheet printout
- Unglazed porcelain tile (or the bottom of a coffee mug)
- Paper plate or disposable pie pan
- Microscope slide
- Magnifying glass
- Cup of water
- Steel nail
- Double-sided tape
- Magnet
NEW
OLD
First Law of Thermodynamics: Energy is conserved. Energy is the ability to do work. Work is moving something against a force over a distance. Force is a push or a pull, like pulling a wagon or pushing a car. Energy cannot be created or destroyed, but can be transformed.
Materials: ball, string
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Click here to go to next lesson on Combustion.
A battery is a device that produces electrical energy from a chemical reaction. Another name for a battery is voltaic cell. Voltaic means to make electricity.
Most batteries contain two or more different chemical substances. The different chemical substances are usually separated from each other by a barrier. One side of the barrier is the positive terminal of the battery and the other side of the barrier is the negative terminal. When the positive and negative terminals of a battery are connected to a circuit, a chemical reaction takes place between the two different chemical substances that produces a flow of electrons (electricity).
When a battery is producing electricity, one of the chemical substances in the battery loses electrons. These electrons are then gained by the other chemical substance.
A battery is designed so that the electrons lost by one chemical substance are made to flow through a circuit, such as a flashlight lamp, before being gained by the other chemical substance. A battery will produce a flow of electrons until all of the chemical substances involved in the chemical reaction are completely used.
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Click here to go to next lesson on Electrochemistry Analysis
In this lab, we’re going to investigate the wonders of electrochemistry. Electrochemistry became a new branch of chemistry in 1832, founded by Michael Faraday. Michael Faraday is considered the "father of electrochemistry". The knowledge gained from his work has filtered down to this lab. YOU will be like Michael Faraday. I imagined he would have been overjoyed to do this lab and see the results. You are soooo lucky to be able to take an active part in this experiment. Here's what you're going to do...
You will be “creating” metallic copper from a solution of copper sulfate and water, and depositing it on a negative electrode. Copper is one of our more interesting elements. Copper is a metal, and element 29 on your periodic table. It conducts heat and electricity very well.
Many things around you are made of copper. Copper wire is used in electrical wiring. It has been used for centuries in the form of pipes to distribute water and other fluids in homes and in industry. The Statue of Liberty is a wonderful example of how beautiful 180,000 pounds of copper can be. Yes, it is made of copper, and no, it doesn’t look like a penny…..on the surface. The green color is copper oxide, which forms on the surface of copper exposed to air and water. The oxide is formed on the surface and does not attack the bulk of the copper. You could say that copper oxide protects the copper.
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You will be “creating” metallic copper from a solution of copper sulfate and water, and depositing it on a negative electrode. Copper is one of our more interesting elements. Copper is a metal, and element 29 on your periodic table. It conducts heat and electricity very well.
Many things around you are made of copper. Copper wire is used in electrical wiring. It has been used for centuries in the form of pipes to distribute water and other fluids in homes and in industry. The Statue of Liberty is a wonderful example of how beautiful 180,000 pounds of copper can be. Yes, it is made of copper, and no, it doesn’t look like a penny…..on the surface. The green color is copper oxide, which forms on the surface of copper exposed to air and water. The oxide is formed on the surface and does not attack the bulk of the copper. You could say that copper oxide protects the copper.
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Click here for Potassium Permanganate
Magnesium is one of the most common elements in the Earth’s crust. This alkaline earth metal is silvery white, and soft. As you perform this lab, think about why magnesium is used in emergency flares and fireworks. Farmers use it in fertilizers, pharmacists use it in laxatives and antacids, and engineers mix it with aluminum to create the BMW N52 6-cylinder magnesium engine block. Photographers used to use magnesium powder in the camera’s flash before xenon bulbs were available.
Most folks, however, equate magnesium with a burning white flame. Magnesium fires burn too hot to be extinguished using water, so most firefighters use sand or graphite.
We’re going to learn how to (safely) ignite a piece of magnesium in the first experiment, and next how to get energy from it by using it in a battery in the second experiment. Are you ready?
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Click here to go to next lesson on Making Copper
This experiment shows how a battery works using electrochemistry. The copper electrons are chemically reacting with the lemon juice, which is a weak acid, to form copper ions (cathode, or positive electrode) and bubbles of hydrogen.
These copper ions interact with the zinc electrode (negative electrode, or anode) to form zinc ions. The difference in electrical charge (potential) on these two plates causes a voltage.
Materials:
- one zinc and copper strip
- two alligator wires
- digital multimeter
- one fresh large lemon or other fruit
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Mars is coated with iron oxide, which not only covers the surface but is also present in the rocks made by the volcanoes on Mars.
Today you get to perform a chemistry experiment that investigates the different kinds of rust and shows that given the right conditions, anything containing iron will eventually break down and corrode. When iron rusts, it’s actually going through a chemical reaction: Steel (iron) + Water (oxygen) + Air (oxygen) = Rust
Materials
- Four empty water bottles
- Four balloons
- Water
- Steel wool
- Vinegar
- Water
- Salt
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Never polish your tarnished silver-plated silverware again! Instead, set up a ‘silverware carwash’ where you earn a nickel for every piece you clean. (Just don’t let grandma in on your little secret!)
We’ll be using chemistry and electricity together (electrochemistry) to make a battery that reverses the chemical reaction that puts tarnish on grandma’s good silver. It’s safe, simple, and just needs a grown-up to help with the stove.
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Click here to go to next lesson on Batteries storing energy
If you don’t have equipment lying around for this experiment, wait until you complete Unit 10 (Electricity) and then come back to complete this experiment. It’s definitely worth it!
Electroplating was first figured out by Michael Faraday. The copper dissolves and shoots over to the key and gets stuck as a thin layer onto the metal key. During this process, hydrogen bubbles up and is released as a gas. People use this technique to add material to undersized parts, for place a protective layer of material on objects, to add aesthetic qualities to an object.
Materials:
- one shiny metal key
- 2 alligator clips
- 9V battery clip
- copper sulfate (MSDS)
- one copper strip or shiny copper penny
- one empty pickle jar
- 9V battery
Click here to go to next lesson on Electrochemical cells and voltage
This experiment is just for advanced students. If you guessed that this has to do with electricity and chemistry, you’re right! But you might wonder how they work together. Back in 1800, William Nicholson and Johann Ritter were the first ones to split water into hydrogen and oxygen using electrolysis. (Soon afterward, Ritter went on to figure out electroplating.) They added energy in the form of an electric current into a cup of water and captured the bubbles forming into two separate cups, one for hydrogen and other for oxygen.
This experiment is not an easy one, so feel free to skip it if you need to. You don’t need to do this to get the concepts of this lesson but it’s such a neat and classical experiment (my students love it) so you can give it a try if you want to. The reason I like this is because what you are really doing in this experiment is ripping molecules apart and then later crashing them back together.
Have fun and please follow the directions carefully. This could be dangerous if you’re not careful. The image shown here is using graphite from two pencils sharpened on both ends, but the instructions below use wire. Feel free to try both to see which types of electrodes provide the best results.
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Click here to go to next lesson on Electroplating
Electricity. Chemistry. Nothing in common, have nothing to do with each other. Wrong! Electrochemistry has been a fact since 1774. Once electricity was applied to particular solutions, changes occurred that scientists of the time did not expect.
In this lab, we will discover some of the same things that Farraday found over 300 years ago. We will be there as things tear apart, particles rush about, and the power of attraction is very strong. We’re not talking about dancing, we’re talking about something much more important and interesting….we’re talking about ELECTROCHEMISTRY!
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Click here to go to next lesson on Electrolysis
If you guessed that electrochemistry has to do with electricity and chemistry, you’re right! But you might wonder how they work together. Back in 1800, William Nicholson and Johann Ritter were the first ones to split water into hydrogen and oxygen using electrolysis. (Soon afterwards, Ritter went on to figure out electroplating.) They added energy in the form of an electric current into a cup of water and captured the bubbles forming into two separate cups, one for hydrogen and other for oxygen.
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Click here to go to next lesson on More on Electrochemistry
This is a cool video from a Teacher’s Educational Channel in Europe I thought you might enjoy about the science of fireworks:
You can view the full video here.
Click here to go to your next lesson in Electrochemistry.
Charcoal crystals uses evaporation to grow the crystals, which will continue to grow for weeks afterward. You’ll need a piece of very porous material, such as a charcoal briquette, sponge, or similar object to absorb the solution and grow your crystals as the liquid evaporates. These crystals are NOT for eating, so be sure to keep your growing garden away from young children and pets! This project is exclusively for advanced students, as it more involves toxic chemicals than just salt and sugar.
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Click here to go to next lesson on Science of Fireworks
Potassium perchlorate is usually safer than chlorate salt, but it sometimes is hard to get it. In the past, the only supplier in the US makes ammonium perchlorate, the oxidizer that was used with the space shuttle booster rockets, and each shuttle launch required 1.5 million pounds of it, which was twice the annual consumption rate, so when there were a lot of shuttle launches, the fireworks market took a hit and it was near impossible to get any potassium perchlorate.
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Click here to go to next lesson on Charcoal Crystals
Second Law of Thermodynamics: Heat flows from hot to cold. Heat is the movement of thermal energy from one object to another. Heat can only flow from an object of a higher temperature to an object of a lower temperature. Heat can be transferred from one object to another through conduction, convection and radiation.
Temperature is basically a speedometer for molecules. The faster they are wiggling and jiggling, the higher the temperature and the higher the thermal energy that object has. Your skin, mouth and tongue are antennas which can sense thermal energy. When an object absorbs heat it does not necessarily change temperature.
Materials: hot cup of cocoa
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Click here to go to next lesson on Fireworks
First Law of Thermodynamics: Energy is conserved. Energy is the ability to do work. Work is moving something against a force over a distance. Force is a push or a pull, like pulling a wagon or pushing a car. Energy cannot be created or destroyed, but can be transformed.
Materials: ball, string
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Click here to go to next lesson on Thermodynamics: Second law
What do you do if you don’t know the concentration of a solution? We use a method called titration to determine how many moles are present in the solution of an acid or a base by neutralizing it. A titration curve is when you graph out the pH as you drop it in the solution.
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Click here to go to next lesson on pH and solubility
This experiment is for advanced students. All chemical reactions are equilibrium reactions. This experiment is really cool because you’re going to watch how a chemical reaction resists a pH change.
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Click here to go to next lesson on Titrations and pH curves
Cobalt chloride (CoCl2) has a dramatic color change when combined with water, making it a great water indicator. A concentrated solution of cobalt chloride is red at room temperature, blue when heated, and pale-to-clear when frozen. The cobalt chloride we’re using is actually cobalt chloride hexahydrate, which means that each CoCl2 molecule also has six water molecules (6H2O) stuck to it.
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Click here to go to next lesson on Potassium Hexacynoferrate
If you love the idea of mixing up chemicals and dream of having your own mad science lab one day, this one is for you. You are going to mix up each solid with each liquid in a chemical matrix.
In a university class, one of the first things you learn in chemistry is the difference between physical and chemical changes. An example of a physical change happens when you change the shape of an object, like wadding up a piece of paper. If you light the paper wad on fire, you now have a chemical change. You are rearranging the atoms that used to be the molecules that made up the paper into other molecules, such as carbon monoxide, carbon dioxide, ash, and so forth.
How can you tell if you have a chemical change? If something changes color, gives off light (such as the light sticks used around Halloween), or absorbs heat (gets cold) or produces heat (gets warm), it’s a chemical change.
What about physical changes? Some examples of physical changes include tearing cloth, rolling dough, stretching rubber bands, eating a banana, or blowing bubbles.
About this experiment: Your solutions will turn red, orange, yellow, green, blue, purple, hot, cold, bubbling, foaming, rock hard, oozy, and slimy, and they’ll crystallize and gel — depending on what you put in and how much!
This is the one set of chemicals that you can mix together without worrying about any lethal gases. I do recommend doing this OUTSIDE, as the alcohol and peroxide vapors can irritate you. Always have goggles on and gloves on your hands, and a hose handy in case of spills. Although these chemicals are not harmful to your skin, they can cause your skin to dry out and itch. Wear gloves (latex or similar) and eye protection (safety goggles), and if you’re not sure about an experiment or chemical, just don’t do it. (Skip the peroxide and cold pack if you have small kids.)
Materials:
• sodium tetraborate (borax, laundry aisle)
• sodium bicarbonate (baking soda, baking aisle)
• sodium carbonate (washing soda, laundry aisle)
• calcium chloride (AKA “DriEz” or “Ice Melt”)
• citric acid (spice section, used for preserving and pickling)
• ammonium nitrate (single-use disposable cold pack)
• isopropyl rubbing alcohol
• hydrogen peroxide
• acetic acid (distilled white vinegar)
• water
• liquid dish soap (add to water)
• muffin tin or disposable cups
• popsicle sticks for stirring and mixing
• tablecloths (one for the table, another for the floor)
• head of red cabbage (indicator)
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Click here to go to next lesson on Cobalt Colors
Phenolphthalein is a weak, colorless acid that changes color when it touches acidic (turns orange) or basic (turns pink/fuchsia) substances. People used to take it as a laxative (not recommended today, as ingesting high amounts may cause cancer). Use gloves when handling this chemical, as your skin can absorb it on contact. I’ll show you how:
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Click here to go to next lesson on Acid-base Matrix
You can go your whole life without paying any attention to the chemistry behind acids and bases. But you use acids and bases all the time! They are all around you. We identify acids and bases by measuring their pH.
Every liquid has a pH. If you pay particular attention to this lab, you will even be able to identify most acids and bases and understand why they do what they do. Acids range from very strong to very weak. The strongest acids will dissolve steel. The weakest acids are in your drink box. The strongest bases behave similarly. They can burn your skin or you can wash your hands with them.
Acid rain is one aspect of low pH that you can see every day if you look for it. This is a strange name, isn’t it? We get rained on all the time. If people were dissolving, if the rain made their skin smoke and burn, you’d think it would make headlines, wouldn’t you? The truth is acid rain is too weak to harm us except in very rare and localized conditions. But it’s hard on limestone buildings.
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Click here to go to next lesson on Water to Wine
You can go your whole life without paying any attention to the chemistry behind acids and bases. But you use acids and bases all the time! They are all around you. We identify acids and bases by measuring their pH.
Every liquid has a pH. If you pay particular attention to this lab, you will even be able to identify most acids and bases and understand why they do what they do. Acids range from very strong to very weak. The strongest acids will dissolve steel. The weakest acids are in your drink box. The strongest bases behave similarly. They can burn your skin or you can wash your hands with them.
Acid rain is one aspect of low pH that you can see every day if you look for it. This is a strange name, isn’t it? We get rained on all the time. If people were dissolving, if the rain made their skin smoke and burn, you’d think it would make headlines, wouldn’t you? The truth is acid rain is too weak to harm us except in very rare and localized conditions. But it’s hard on limestone buildings.
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Click here to go to next lesson on Making Litmus Paper
Strong acids and strong bases (which we’ll talk about in a minute) all have one thing in common: they break apart (completely dissociate) into ions when placed in water. This means that once you dunk the acid molecule in water, it splits apart and does not exist as a whole molecule in water. Strong acids form H+ and a negative ion
The seven strong acids are: hydrochloric acid (HCl), nitric acid (HNO3) used in fireworks and explosives, sulfuric acid (H2SO4) which is the acid in your car battery, hydrobromic acid (HBr), hydroiodic acid (HI), and perchloric acid (HClO4). The record-holder for the world’s strongest acid are the carborane (CAR-bor-ane) superacids (over a million times stronger than concentrated sulfuric acid).
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The seven strong acids are: hydrochloric acid (HCl), nitric acid (HNO3) used in fireworks and explosives, sulfuric acid (H2SO4) which is the acid in your car battery, hydrobromic acid (HBr), hydroiodic acid (HI), and perchloric acid (HClO4). The record-holder for the world’s strongest acid are the carborane (CAR-bor-ane) superacids (over a million times stronger than concentrated sulfuric acid).
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Click here to go to next lesson on Making Litmus Paper
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Click here to download Homework Problem Set #11.
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Click here for Gravimetric Calculations.
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Click here to go to next lesson on Acid and Base Reactions.
Strong acids and strong bases (which we’ll talk about in a minute) all have one thing in common: they break apart (completely dissociate) into ions when placed in water. This means that once you dunk the acid molecule in water, it splits apart and does not exist as a whole molecule in water. Strong acids form H+ and a negative ion
The seven strong acids are: hydrochloric acid (HCl), nitric acid (HNO3) used in fireworks and explosives, sulfuric acid (H2SO4) which is the acid in your car battery, hydrobromic acid (HBr), hydroiodic acid (HI), and perchloric acid (HClO4). The record-holder for the world’s strongest acid are the carborane (CAR-bor-ane) superacids (over a million times stronger than concentrated sulfuric acid).
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Click here to go to next lesson on K w and the pH scale
First discovered in 1886 by Hans Heinrich Landolt, the iodine clock reaction is one of the best classical chemical kinetics experiments. Here’s what to expect: Two clear solutions are mixed. At first there is no visible reaction, but after a short time, the liquid suddenly turns dark blue.
Usually, this reaction uses a solution of hydrogen peroxide with sulfuric acid, but you can substitute a weaker (and safer) acid that works just as well: acetic acid (distilled white vinegar). The second solution contains potassium iodide, sodium thiosulfate (crystals), and starch (we’re using a starch packing peanut, but you can also use plain old cornstarch). Combine one with the other to get the overall reaction, but note that there are actually two reactions happening simultaneously.
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Click here for the next lesson in Iodine.
Chemical equilibrium is the condition that happens when the concentration of the reactants and products don’t have any net change over time. This doesn’t mean that the reaction stops, just that the producing and consuming of the molecules is in balance.
Most chemical reactions are reversible, just like phases changes. Do you remember the hot icicle experiment? Do you remember how to get it back to the starting point? You have to add energy to the solid sodium acetate to turn it back into a liquid, so it can turn back into a solid again. Then let that experiment sit for a bit (overnight or about 12 hours) and in the morning, you’ll have crystals growing on your pipe cleaner. Now if you want to reverse this reaction, all you have to do is add energy to the system and the crystals will dissolve back into the solution. You can heat it up in the microwave or in a pot of water on the stove, and the crystals will disappear.
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Click here to go to next lesson on Iodine Clock reaction
Chemical equilibrium is the condition that happens when the concentration of the reactants and products don’t have any net change over time. This doesn’t mean that the reaction stops, just that the producing and consuming of the molecules is in balance.
Most chemical reactions are reversible, just like phases changes. Do you remember the hot icicle experiment? Do you remember how to get it back to the starting point? You have to add energy to the solid sodium acetate to turn it back into a liquid, so it can turn back into a solid again. Then let that experiment sit for a bit (overnight or about 12 hours) and in the morning, you’ll have crystals growing on your pipe cleaner. Now if you want to reverse this reaction, all you have to do is add energy to the system and the crystals will dissolve back into the solution. You can heat it up in the microwave or in a pot of water on the stove, and the crystals will disappear.
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Click here to go to next lesson on Le Chatelier’s principle
Hydrogen peroxide is used to fuel rockets, airplanes, and other vehicle engines. Chemistry teachers everywhere use it to demonstrate the power of a catalyst.
To speed up a reaction without altering the chemistry of the reaction involves adding a catalyst. A catalyst changes the rate of reaction but doesn’t get involved in the overall chemical changes.
For example, leaving a bottle of hydrogen peroxide outside in the sunlight will cause the hydrogen peroxide to decompose. However, this process takes a long time, and if you don’t want to wait, you can simply toss in a lump of charcoal to speed things along.
The carbon is a catalyst in the reaction, and the overall effect is that instead of taking two months to generate a balloon full of oxygen, it now only takes five minutes. The amount of charcoal you have at the end of the reaction is exactly the same as before it started.
A catalyst can also slow down a reaction. A catalytic promoter increases the activity, and a catalytic poison (also known as a negative catalyst, or inhibitor) decreases the activity of a reaction. Catalysts offer a different way for the reactants to become products, and sometimes this means the catalyst reacts during the chemical reaction to form intermediates. Since the catalyst is completely regenerated before the reaction is finished, it’s considered ‘not used’ in the overall reaction.
In this experiment, you’ll see that there’s a lot of oxygen hiding inside the peroxide – enough to really make things interesting and move around! You’ll also find out what happens to soap when you bubble oxygen through it. Are you ready?
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Click here to go to next lesson on Collision Theory
Chemists want to control not only what comes out of a chemical reaction, but how fast the reaction occurs. For example, scientists are working to slow down the depletion rate of the ozone in the upper level of our atmosphere, so we stay protected from harmful UV rays.
The rate of the chemical reaction of a nail rusting is slow compared to how fast baking soda reacts with vinegar. Different factors affect the speed of the reaction, but the main idea is that the more collisions between particles, the faster the reaction will take place.
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Click here to go to next lesson on Dinosaur Toothpaste
This experiment is for advanced students. Hydrolysis is a chemical reaction that involves breaking a molecular bond using water. In chemistry, there are three different types of hydrolysis: sat hydrolysis, acid hydrolysis, and base hydrolysis. In nature, living organisms survive by making their energy from processing food. The energy converted from food is stored in ATP molecules. To release the energy stored in food, a phosphate group breaks off an ATP molecule (and becomes ADP) using hydrolysis and releases energy from the bonds.
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Click here to go to next lesson on Catalysts
Hydrolysis is a chemical reaction that happens when a molecule splits into two parts when water is added. One part gains a hydrogen (H+) and the other gets the hydroxyl (OH–) group. The reaction in the experiment forms starch from glucose, and when we add water, it breaks down the amino acid components just like the enzymes do in your stomach when they digest food.
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Click here to go to next lesson on Hydrolysis
Plasma makes up a very large percentage of the matter in the universe. Not much of it is on Earth and the plasma that is here is very short lived or stuck in a tube. Plasma is basically what happens when you add enough energy to a gas that the atoms move and vibrate around so energetically that they smack into each other and rip electrons off each other, so you have positively charged atoms (called ions) that lost their electrons, and also the electrons themselves which are negatively charged, all zinging around in the gas.
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Click here for the next lesson in Osmosis.
This experiment is for advanced students.Have you ever taken a gulp of the ocean? Seawater can be extremely salty! There are large quantities of salt dissolved into the water as it rolled across the land and into the sea. Drinking ocean water will actually make you thirstier (think of eating a lot of pretzels). So what can you do if you’re deserted on an island with only your chemistry set?
Let me show you how to take the salt out of water with this easy setup.
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Click here to go to next lesson on Other states of matter
Instead of using glue as a polymer (as in the slime recipes above), we're going to use PVA (polyvinyl alcohol). Most liquids are unconnected molecules bouncing around. Monomers (single molecules) flow very easily and don't clump together. When you link up monomers into longer segments, you form polymers (long chains of molecules).
Polymers don't flow very easily at all - they tend to get tangled up until you add the cross-linking agent, which buddies up the different segments of the molecule chains together into a climbing-rope design.
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Click here to go to next lesson on Desalination
When you think of slime, do you imagine slugs, snails, and puppy kisses? Or does the science fiction film The Blob come to mind? Any way you picture it, slime is definitely slippery, slithery, and just plain icky — and a perfect forum for learning real science.
But which ingredients work in making a truly slimy concoction, and why do they work? Let’s take a closer look…
Imagine a plate of spaghetti. The noodles slide around and don’t clump together, just like the long chains of molecules (called polymers) that make up slime. They slide around without getting tangled up. The pasta by itself (fresh from the boiling water) doesn’t hold together until you put the sauce on. Slime works the same way. Long, spaghetti-like chains of molecules don’t clump together until you add the sauce … until you add something to cross-link the molecule strands together.
The sodium-tetraborate-and-water mixture is the “spaghetti” (the long chain of molecules, also known as a polymer), and the “sauce” is the glue-water mixture (the cross-linking agent). You need both in order to create a slime worthy of Hollywood filmmakers.
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Click here to go to next lesson on PVA
The glue is a polymer, which is a long chain of molecules all hooked together like tangled noodles. When you mix the two solutions together, the water molecules start linking up the noodles together all along the length of each noodle to get more like a fishnet. Scientists call this a polymetric compound of sodium tetraborate and lactated glue. We call it bouncy putty.
Here’s what you do:
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Click here to go to next lesson on Glowing Slime
This is one of those ‘chemistry magic show’ type of experiments to wow your friends and family. Here’s the scoop: you take a cup of clear liquid, add it to another cup of clear liquid, stir for ten seconds, and you’ll see a color change, a state change from liquid to solid, and you can pull a rubber-like bouncy ball right out of the cup.
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Click here to go to next lesson on Bouncy Putty
Imagine a plate of spaghetti. The noodles slide around and don’t clump together, just like the long chains of molecules (called polymers) that make up slime. They slide around without getting tangled up. The pasta by itself (fresh from the boiling water) doesn’t hold together until you put the sauce on. Slime works the same way. Long, spaghetti-like chains of molecules (called polymers) don’t clump together until you add the sauce – something that cross-links the molecule strands (polymer) together.
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Click here to go to next lesson on Bouncy Ball
Did you know that supercooled liquids need to heat up in order to freeze into a solid? It’s totally backwards, I know…but it’s true! Here’s the deal:
A supercooled liquid is a liquid that you slowly and carefully bring down the temperature below the normal freezing point and still have it be a liquid. We did this in our Instant Ice experiment.
Since the temperature is now below the freezing point, if you disturb the solution, it will need to heat up in order to go back up to the freezing point in order to turn into a solid.
When this happens, the solution gives off heat as it freezes. So instead of cold ice, you have hot ice. Weird, isn’t it?
Sodium acetate is a colorless salt used making rubber, dying clothing, and neutralizing sulfuric acid (the acid found in car batteries) spills. It’s also commonly available in heating packs, since the liquid-solid process is completely reversible – you can melt the solid back into a liquid and do this experiment over and over again!
The crystals melt at 136oF (58oC), so you can pop this in a saucepan of boiling water (wrap it in a towel first so you don’t melt the bag) for about 10 minutes to liquify the crystals.
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Click here to go to next lesson on Water
Find a low pressure (like the pressure you feel right now – it’s called 1 atm). Put your finder on the 1 mark on the vertical side (next to the “P”, which stands for Pressure) and follow the dashed line straight across. As you move across, so you notice how at low temperatures you’re in the ice region, but when you hit zero, you turn to water, and for temperatures below 100 deg C you’re only in the liquid water phase?
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Click here to go to next lesson on Enthalpy and Heat Capacity Calculations.
While this isn’t actually an air-pressure experiment but more of an activity in density, really, it’s still a great visual demonstration of why Hot Air Balloons rise on cold mornings.
Imagine a glass of hot water and a glass of cold water sitting on a table, side by side. Now imagine you have a way to count the number of water molecules in each glass. Which glass has more water molecules?
The glass of cold water has way more molecules… but why? The cold water is more dense than the hot water. Warmer stuff tends to rise because it’s less dense than colder stuff and that’s why the hot air balloon in experiment 1.10 floated up to the sky.
Clouds form as warm air carrying moisture rises within cooler air. As the warm, wet air rises, it cools and begins to condense, releasing energy that keeps the air warmer than its surroundings. Therefore, it continues to rise. Sometimes, in places like Florida, this process continues long enough for thunderclouds to form. Let’s do an experiment to better visualize this idea.
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Click here to go to next lesson on Supercooling.
Indoor Rain Clouds
Making indoor rain clouds demonstrates the idea of temperature, the measure of how hot or cold something is. Here’s how to do it:
Take two clear glasses that fit snugly together when stacked. (Cylindrical glasses with straight sides work well.)
Fill one glass half-full with ice water and the other half-full with very hot water (definitely an adult job – and take care not to shatter the glass with the hot water!). Be sure to leave enough air space for the clouds to form in the hot glass.
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Click here to go to next lesson on Genie in a Bottle
When something changes state, goes from like a liquid to a solid, all of the substance must change to the next state. For example, at 100° C all the water must change from a liquid to a gas. The temperature stays constant until it’s completely changed state. It’s kind of weird when you think about it.
If you were able to take the temperature of water as it changed from a solid (ice) to a liquid you would notice that the temperature stays at 32° F until that piece of ice was completely melted. The temperature would not increase at all.
Even if that ice was in an oven, the temperature would stay the same. Once all the solid ice had disappeared, then you would see the temperature of the puddle of water increase.
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Click here to go to next lesson on freeze swap
As promised, here’s the Liquid Nitrogen Ice Cream Social video that was only available to a handful of participants at our live summer camp last week! This is probably one of the last times Dr. Tom Frey will be doing this presentation, so we didn’t want to miss the opportunity to record it and share it with you!
Dr. Tom Frey just retired as a chemistry professor at Cal Poly State University, where he taught courses (including how to make your own lab glassware) for 42 years. He’s not only a mentor of mine, but a close personal friend and I am happy to share his talent and passion for science with you through this special, one of a kind video.
I really hope you enjoy it!
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Click here to go to next lesson on Phase changes and temperature
A liquid has a definite volume (meaning that you can’t compress or squish it into a smaller space), but takes the shape of its container. Think of a water-filled balloon. When you smoosh one end, the other pops out. Liquids are generally incompressible, which is what hydraulic power on heavy duty machinery (like excavators and backhoes) is all about.
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Click here to go to next lesson on Liquid Nitrogen
Can we really make crystals out of soap? You bet! These crystals grow really fast, provided your solution is properly saturated. In only 12 hours, you should have sizable crystals sprouting up.
You can do this experiment with either skewers, string, or pipe cleaners. The advantage of using pipe cleaners is that you can twist the pipe cleaners together into interesting shapes, such as a snowflake or other design. (Make sure the shape fits inside your jar. )
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Click here to go to next lesson on Liquids
Solids
What makes the solids, liquids, gases etc. different is basically the energy (motion) of the atoms. From BEC, where they are so low energy that they are literally blending into one another, to plasma, where they are so high energy they can emit light. Solids are the lowest energy form of matter that exist in nature (BEC only happens under laboratory conditions).
In solids, the atoms and molecules are bonded (stuck) together in such a way that they can’t move easily. They hold their shape. That’s why you can sit in a chair. The solid molecules hold their shape and so they hold you up. The typical characteristics that solids tend to have are they keep their shape unless they are broken and that they do not flow.
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Click here to go to next lesson on Borax Crystals
An average can of soda at room temperature measures 55 psi before you ever crack it open. (In comparison, most car tires run on 35 psi, so that gives you an idea how much pressure there is inside the can!)
If you heat a can of soda, you’ll run the pressure over 80 psi before the can ruptures, soaking the interior of your house with its sugary contents. Still, you will have learned something worthwhile: adding energy (heat) to a system (can of soda) causes a pressure increase. It also causes a volume increase (kaboom!).
How about trying a safer variation of this experiment using water, an open can, and implosion instead of explosion?
Materials – An empty soda can, water, a pan, a bowl, tongs, and a grown-up assistant.
NOTE: If you can get a hold of one, use a beer can – they tend to work better for this experiment. But you can also do this with a regular old soda can. And no, I am not suggesting that kids should be drinking alcohol! Go ask a parent to find you one – and check the recycling bin.
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Click here to go to next lesson on Solids
Now let’s take a look at the forces between the molecules themselves. There are four main interactions which really come down to different ways of having opposite charges attract each other.
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Click here to go to next lesson on Vapor pressure and Changes in State
A molecule is the smallest unit of a compound that still has the compound’s properties attached to it. Molecules are made up of two or more atoms held together by covalent bonds.
In the space where electrons from different atoms interact with each other, chemical bonds form. The electrons in the outermost shell are the ones that form the bonds with other atoms.
When the atoms share the electron(s), a covalent bond is formed. Electrons aren’t perfect, though, and usually an electron is more attracted to one atom than another, which forms a polar covalent bond between atoms (like in water, H2O).
While it may seem a bit random right now, with a little bit of study, you’ll find you can soon understand how molecules are formed and the shapes they choose once you figure out the types of bonds that can form.
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Click here to go to next lesson on Intermolecular Forces
This experiment is for advanced students.Have you ever taken a gulp of the ocean? Seawater can be extremely salty! There are large quantities of salt dissolved into the water as it rolled across the land and into the sea. Drinking ocean water will actually make you thirstier (think of eating a lot of pretzels). So what can you do if you’re deserted on an island with only your chemistry set?
Let me show you how to take the salt out of water with this easy setup.
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Click here to go to next lesson on Covalent Bonds and Polarity
We’re going to take two everyday materials, salt and vinegar, and use them to grow crystals by creating a solution and allowing the liquids to evaporate. These crystals can be dyed with food coloring, so you can grow yourself a rainbow of small crystals overnight.
The first thing you need to do is gather your materials. You will need:
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Click here to go to next lesson on Desalination
We’re going to take two everyday materials, salt and vinegar, and use them to grow crystals by creating a solution and allowing the liquids to evaporate. These crystals can be dyed with food coloring, so you can grow yourself a rainbow of small crystals overnight.
The first thing you need to do is gather your materials. You will need:
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Click here to go to next lesson on Rock Candy
There are different kinds of bonds that can form in a molecule. When two atoms approach each other close enough for their electron clods to interact, the electrons of one repels the electrons in the other, and the same thing happens within the nucleus of the atoms. At the same time, each atom’s negatively charged electron is attracted to the other atom’s positively charged nucleus. If the atoms still come closer, the attractive forces offset the repulsive and the energy of the atom decreases and bonds are formed – the atom sticks together. When the energy decrease is small, the bonds are van der Waals. When the energy decrease is larger, we have chemical bonds, either ionic or covalent.
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Click here to go to next lesson on Salt and Sugar Crystals
If you’ve ever had a shot, you know how cold your arm feels when the nurse swipes it with a pad of alcohol. What happened there? Well, alcohol is a liquid with a fairly low boiling point. In other words, it goes from liquid to gas at a fairly low temperature. The heat from your body is more then enough to make the alcohol evaporate.
As the alcohol went from liquid to gas it sucked heat out of your body. For things to evaporate, they must suck in heat from their surroundings to change state. As the alcohol evaporated you felt cold where the alcohol was. This is because the alcohol was sucking the heat energy out of that part of your body (heat was being transferred by conduction) and causing that part of your body to decrease in temperature.
As things condense (go from gas to liquid state) the opposite happens. Things release heat as they change to a liquid state. The water gas that condenses on your mirror actually increases the temperature of that mirror. This is why steam can be quite dangerous. Not only is it hot to begin with, but if it condenses on your skin it releases even more heat which can give you severe burns. Objects absorb heat when they melt and evaporate/boil. Objects release heat when they freeze and condense.
Do you remember when I said that heat and temperature are two different things? Heat is energy – it is thermal energy. It can be transferred from one object to another by conduction, convection, and radiation. We’re now going to explore heat capacity and specific heat. Here’s what you do:
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Click here for your next lesson on Triple Point.
They can have a thermal energy but they can’t have heat. Heat is really the transfer of thermal energy. Or, in other words, the movement of thermal energy from one object to another.
If you put an ice cube in a glass of lemonade, the ice cube melts. Which way does heat flow?
The thermal energy from your lemonade moves to the ice cube.
The movement of thermal energy is called heat. The ice cube receives heat from your lemonade. Your lemonade gives heat to the ice cube.
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