When you cut open an apple it doesn’t look good for very long does it? After even just a few minutes an apple can start to look brown inside. The apple turns brown because you cut the apple open and exposed what’s inside the apple skin to the air, which has oxygen in it. Oxidation is a chemical reaction that takes place when a substance combines with oxygen. When apple flesh combines with oxygen it turns brown. The browning of the apple is called oxidation.
Another kind of oxidation you probably have seen is rust. When metal comes in contact with oxygen a chemical reaction takes place – oxidation. In this case the result of oxidation is rust.
What You Need:
3 Apple Slices
1 Orange Slice
1/2 Cup Orange Juice
3 Small Plates
Carmel Dip and the Rest of the Apple Slices (optional)
Put one apple slice on each plate. One apple slice leave alone. Pour the orange juice over one apple slice, pour orange juice over one apple slice and lay the orange slice on top of the last apple slice. Wait a couple hours. How do the apple slices compare? Which one is the most brown?
Here are some websites and books to help you understand oxidation:
An insulatoris a substance that prevents the transfer of heator cold. Your winter hat is an insulator. It keeps the cold in the winter air from making your head cold. It blocks the transfer of cold from the air to you. It also blocks the transfer of heat from your head to the air.
Here is an experiment that will show you how different materials make better insulators than others.
What You Need:
3 Identical Coffee Mugs
4 Rubber Bands
Cotten Fabric (t-shirt – check the label)
Wrap the paper towel around the outside of one mug and secure it with a rubber band. Do the same with the other three mugs using alumninum foil, cotton and the wool sock.
Fill a pitcher with very hot tap water. Be careful! Take the temperature of the water and write the temperature down.
Fill each cup to the top with the hot tap water. Wait five minutes and take the temperature of the water in each cup. Make a chart to keep track of each cup’s temperature. Record each temperature after 5 minutes, 10 minutes and 15 minutes. What happens to the temperature of the water in each cup?
Here are some websites and books that will help you understand heat and insulators:
Words to Know: Insulator - A reduction of heat transfer between objects. Insulators keep cool things cool and warm things warm – like the thermos in your lunch box or the blubber on marine mammals. Heat - A high temperature. Temperature – The level of heat present in a substance or of an object or person. Temperature is measured on a thermometer and expressed in number of degrees. Temperature can also be determined by using the sense of touch. Human skin is sensitive to changes in temperature.
Animals on earth need a certain amount of heat to stay healthy and alive. How is it then, that animals like polar bars can survive in the arctic? How is it that whales can survive in the deep, freezing cold ocean? These animals have blubber, a layer of fat that acts as an insulator.
An insulator is a substance that prevents the transfer of heat or cold. The layer of blubber on a whale acts as a barrier to the cold of the ocean water. Because of its layer of blubber, the internal organs of the whale stay warm.
Your winter coat is an insulator. It keeps the cold in the winter air from making your body cold. It blocks the transfer of cold from the air to you. It also blocks the transfer of heat from your body to the air.
Here is an experiment that will show you how a simple insulator can make a big difference.
What You Need:
4 ziploc bags
Crisco Shortening or Vaseline
Fill a bowl with water and ice cubes. Put your hand inside one empty ziploc bag. Put that same hand with the bag on it inside a second ziploc bag. Now put your hand with the bags on it in the bowl of ice water. How long does it take for your hand to feel cold?
Ok, take your hand out of the bowl and take the bags off. Now fill one ziplic bag 1/2 full of Crisco or Vaseline. Put your hand inside one empty ziploc bag. Now put that same hand, with the bag on it, inside the bag full of Crisco or Vaseline. Squish the Crisco or Vaseline around so that it surrounds your hand. Now put your bag covered hand in the bowl of ice water. How long does it take for your hand to get cold?
The Crisco or Vaseline is an insulator, just like blubber. It stops the coldness of the ice water from transferring to your hand.
Words to Know: Insulator - A reduction of heat transfer between objects. Insulators keep cool things cool and warm things warm – like the thermos in your lunch box or the blubber on marine mammals. Heat - A high temperature. Blubber – A layer of fat that some animals have that helps keep the animals warm. Animals that have blubber include whales and sea lions, that live in the cold ocean and polar bears, that live in polar regions. Temperature – The level of heat present in a substance or of an object or person. Temperature is measured on a thermometer and expressed in number of degrees. Temperature can also be determined by using the sense of touch. Human skin is sensitive to changes in temperature.
Have an adult help you light a candle that can sit safely on a table. Blow up one balloon and tie it closed. Hold the balloon a couple inches from the candle flame. What happens? It pops, of course.
Now take the second balloon. Fill it with water. Don’t fill it with so much water it starts to expand. This is not going to be a water balloon. Now take the balloon with water in it and blow it up the rest of the way. Tie it closed. Hold this balloon a couple inches above the candle flame. Does it pop? How long does it take?
Balloons are made out of rubber. Rubber heats up really fast so the first balloon pops fast. Water molecules take a long time to heat up. The heat from the candle is soaked up by the water inside the second balloon so that balloon does not pop right away.
Science Experiment Idea: Try different temperatures of water in the balloon. If the water is warmer it seems like the balloon would pop faster. Test it out and see. Try ice water, room temperature water and hot tap water (NOT too hot to touch!). Make sure you use three balloons that are exactly the same. Measure the same amount of water into each balloon. Hold each balloon the same distance away from the candle flame. Remember that you only want ONE variable in an experiment. The variable is the one thing that changes, in this case the variable is the temperature of the water. Use a stopwatch to time how long it takes for the balloon to pop.
Here are some websites and books to help you understand and experiment with the fireproof balloon:
Pour 1/2 cup of milk into a large cup. Add 2 teaspoons vinegar. Mix. Place a coffee filter or paper towel over a second large cup. The coffee filter should sag a little bit to make a little filter bowl. Put a rubber band around the top of the cup so it holds the coffee filter in place. Now pour the milk/vinegar mixture into the filter bowl you made.
Let the liquid part of the mixture drip through the filter. This might take awhile. When the liquid is done dripping use a spoon to scrape the milky lumps off the coffee filter and into a bowl. Add 1/4 teaspoon baking soda to the lumps and mix. Is this substance getting sticky? Try it out – can you use it to glue two pieces of paper together?
When the milk and vinegar (an acid), mix together a chemical reaction takes place. A substance called Casein forms. Casein is a very long molecule that bends like plastic – that’s why the lumps of milk are pliable and bendy. When you add baking soda (a base) to the milk lumps another chemical reactionhappens turning the milk lumps into a sticky glue.
Science Experiment Idea: Make three batchs of milk glue, but make the variable (the thing you change) the amount of baking soda you add to the mixture. If you add 1/8 teaspoon baking soda to one batch, 1/4 teaspoon baking soda to one batch and 1/2 teaspoon baking soda to one batch, which one will be the most sticky? Why do you think so?
Here are some books and website that will help you make and understand glue made from milk: