3.04 Lab: Fizz, Fizz

Purpose

To show that matter is conserved during a chemical reaction.

Background

When substances react chemically, atoms do not appear and disappear to make new compounds. Matter is never created or destroyed, but it can be rearranged. For example, the reaction of hydrogen with oxygen to form water is shown below:

Notice that in order to keep the number of atoms correct before and after the reaction, an extra hydrogen molecule is needed, and an extra water molecule is created.

This characteristic of matter is called the Law of Conservation of Mass. When two or more elements react to produce a compound, the total mass of the compound is the same as the sum of masses of the individual elements that were started with.

Materials

Part 1: The Reaction

1. Use the paper cup during this part of the experiment.
   
   
2. Measure out 25.0 mL of vinegar and pour into the cup.
   
   
3. Measure out 1/2 tsp. of baking soda using a piece of paper towel to hold the baking soda. In the data table below, record the amount of baking soda used.
   
   
4. Add the baking soda to the vinegar slowly. Don't let the bubbles overflow the cup. Observe the reaction and record in the data table.
   
   
5. Before moving on to Part 2, answer the analysis questions for Part 1.

Part 2: Conserving Mass

1. You may use any of the listed materials for this part of the procedure. If you were to mass the contents before and after the reaction, you would notice that the mass was less after the reaction than before.
   
   
2. Based on your answer to #2 in the Part 1 analysis questions, devise a method for repeating the experiment without losing any mass. Use the same amount of reactants, but you may use the different items from the materials list. Part 2 of the analysis questions will ask you to write the procedure that you used.

Analysis Part 1

Consider all that happened during your experiment.

1. Did mass appear to be conserved during this chemical reaction? **Use complete sentences for your answer. Yes or No is not an acceptable answer.**
   
   
2. If you could measure the mass the reactants before and after the reaction, you would see that the mass was less after the reaction. Based on what you observed happening during the reaction, where did the extra mass go? (Remember that mass cannot be destroyed in chemical reactions.)
   

Analysis Part 2

1. Describe how you performed the procedure in Part 2. Use a numbered procedure as your description. Be specific.
   
   
2. Describe how your experiment might prove that mass was conserved.