How to Apply the Law of Conservation of Mass
The law of conservation of mass states that matter is not increased or decreased in a chemical reaction. Matter, however, can be rearranged. It follows then that the mass of the products in an experiment would equal the mass of the reactants. When Albert Einstein discovered the equation E = mc^2 the Laws of Conservation of Mass and Energy were merged into the Law of Conservation of Mass-Energy: This law is utilized in chemistry, mechanics and fluid dynamics. In the universe, the amounts of mass and energy remain constant. We can demonstrate and apply the Law of Conservation of Mass by performing some experiments.
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Things You'll Need
- Safety glasses
- Latex or rubber gloves
- Chemistry set (optional)
- 8 oz plastic cups or test tubes
- Clean glass bowl (holds at least 3 cups)
- Plastic spoon
- 4 oz bottle of school glue
- 1 tsp of borax
- 12 oz water
- Plastic bag with a zip lock
- Rock
- Postal-type scale
- Paper
- Pencil
Instructions
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Look at this picture for a simplistic visual explanation of the Law of Conservation of Mass. There is a 10 cm x 10 cm x 1 cm sheet on the left and of 100 1 cm cubes on the right. The sheet consists of 100 1 8 cm cubes. The sheet was broken down into 100 individual 1 cm cubes. The mass and weight remain the same, but the pieces (matter) are rearranged. You could do the same with a rock by shattering it to pieces.
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Collect all the items needed for your experiments. Before you begin, clean the surface area and wipe it down with water to avoid an unexpected chemical reaction. Place all of your supplies on a flat surface large enough to allow for supplies and the experiment. Put on your gloves and your safety glasses.
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3
Weigh each ingredient in grams before beginning your experiment. First, weigh 1 tsp of borax powder and write the weight down. Weigh the 4 oz bottle of glue and write the weight down. After you empty the bottle, you will weigh it again so you will know how much the glue actually weighed. Weigh the empty 8 oz cup. Now weigh 8 oz of water and 4 oz of glue, subtract the weight of the cup from each and write the numbers down.
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Begin the following experiment to apply the Law of Conservation of Mass. Pour the 4 oz of school glue into an empty 8 oz cup. Then fill the glue bottle with water, shake thoroughly and pour the water in with the glue. You may add a few drops of food coloring to the water in the glue bottle if you want. After you have rinsed out the glue bottle with the 4 oz of water, weigh the empty glue bottle again. Subtract the weight of the empty bottle from the full bottle for the actual weight of the glue.
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Fill a plastic cup with 8 oz of water and stir in the 1 tsp of borax. Now pour the borax solution into the glue solution and stir with your plastic spoon.
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Pull out your gob of slime and roll it into a ball. (If you wish to keep it at the end of the experiment, store it in the Ziploc bag in the refrigerator.)
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Weigh the ball and the leftover water. Add the two weights together. Add the weights of the original ingredients. The two numbers should be the same. You did not lose any mass you just rearranged it.
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Tips & Warnings
White school glue contains polyvinyl alcohol. It is a polymer that will cross-link with certain substances such as borax. Make sure the room where you do your experiments is properly ventilated.
Copper solutions can cause eye infections.
Resources
- Photo Credit Julia Fuller 2008
