Law of Conservation of Mass Lab s1

Law of Conservation of Mass Lab

Purpose: To discover and write the meaning of the Law of Conservation of Mass by observing the masses before and after a physical change and chemical change. Hypothesis: How do you think mass of paper will change after tearing it? How do you think the mass of baking soda and vinegar will change after they react without a balloon covering the reaction? How do you think the mass will change if you cover the reaction with a balloon?

Materials:  balance  funnel  Water Bottle  graduated cylinder  1 balloon  baking soda  sheets of paper  vinegar   Introduction: The word equation for the following reaction is as follows:  vinegar + baking soda ==> sodium acetate + water + carbon dioxide  The chemical equation for the reaction is:

 CH3COOH + NaHCO3 ==> NaC2H3O2 + H2O + CO2  Procedure: Physical Change – Trial 1 Tearing Paper 1. Record the mass of a folded piece of paper on the scale in the table below. 2. Tear the paper into small pieces. Do not lose any pieces. Place them on the scale and record the mass of the torn paper in the table below.  Chemical Change – Reaction of vinegar and baking soda Trial 1  1. Record the mass of the empty water bottle in the table below. Pour about 25 mL of vinegar into the water bottle. Record the mass of the water bottle & vinegar in the table below.  2. Record the Weight of a piece of paper in the table below. Add ~3 g extra of baking soda onto the piece of paper. Record the exact mass of baking soda and paper used in the table below.  3. Place the water/vinegar over a sink. Add the baking soda to the bottle. Record the mass after the baking soda and vinegar have reacted fully as the total mass after reaction.  4. Rinse out the bottle thoroughly  Chemical Change – Reaction of vinegar and baking soda Trial 2  1-2. Complete the same steps as trial 1.  3. Place the water/vinegar on the scale. Add the baking soda to the inside of the balloon. Attach the balloon to the bottle top and then pour the baking soda in. Hold the balloon to the top tight. Record the mass after the baking soda and vinegar have reacted fully as the total mass after reaction.  4. Rinse out the bottle thoroughly.

  Figure 1 Figure 2 Figure 3   Data: Table 1: Physical Change Trial 1 Paper Mass Folded vs Torn  Object  Calculations  Mass  Paper Folded  N/A   Paper Torn  N/A   Table 2: Chemical Change Trial 1 Before and After without Balloon  Object  Calculations  Mas s  Water Bottle  N/A   Water Bottle + Vinegar  N/A   Vinegar Only  (Mass of Water Bottle + Vinegar) – Water  bottle Mass  Paper  N/A   Paper & Baking Soda  N/A   Baking Soda  (Mass of Paper & Baking Soda) – (Mass of  Paper)  Total Mass After  N/A  Reaction  Mass of Reactants  (Mass of Vinegar) + (Mass of Baking Soda)  Before Reaction (Initial Mass)  Mass of Products after  (Total Mass of Scale After Reaction) –  Reaction (Final Mass) (Mass of Water Bottle)          Table 3: Chemical Change Trial 2 Before and After with Balloon  Object  Calculations  Mas s  Water Bottle  N/A   Water Bottle + Vinegar  N/A   Vinegar Only  (Mass of Water Bottle + Vinegar) – Water  bottle Mass  Paper  N/A   Paper & Baking Soda  N/A   Baking Soda  (Mass of Paper & Baking Soda) – (Mass of  Paper)  Total Mass After  N/A  Reaction  Mass of Reactants  (Mass of Vinegar) + (Mass of Baking Soda)  Before Reaction (Initial Mass)  Mass of Products after  (Total Mass of Scale) – (Mass of Water  Reaction (Final Mass) Bottle)  Calculations Calculate the (1) Change in Mass and (2) Percent Change in Mass for Equation 1: Equation 2: Physical Change…. Change in Mass    Percent Change in Mass  

Chemical Change Trial 1 … Change in Mass   Percent Change in Mass   Chemical Change Trial 2 … Change in Mass    Percent Change in Mass 

  Inquiry/Analysis Questions (Refer to Your Notes for this Week for some of the questions):  1. Why was tearing paper a physical change? Why was reacting baking soda and vinegar a chemical change? Explain the difference between a chemical change and physical change. What evidence was there that a chemical change occurred?

          2. What state of matter was present for the paper? What states of matter were the vinegar and baking soda before the reaction? What states of matter were present after the reaction? What was the purpose of the balloon in trial 2 of the chemical change?            3. How did the final mass after the physical change compare with the initial mass of the system(what was the change in mass and the % change in mass)? How did the final mass after the chemical change in trial 1 compare with the initial mass of the system (what was the change in mass and the % change in mass)? How did the final mass after the chemical change in trial 2 compare with the initial mass of the system(what was the change in mass and the % change in mass)?

            4. Was there is a difference between the change in mass chemical change trial 1(without the balloon) vs trial 2(with the balloon)? If so, why was there a difference? The Law of the Conservation of Mass states what happens to the mass of matter during physical and chemical changes. Based on what you observed, what happens to the mass of matter during changes?

         Conclusion: Based on the difference of mass before and after the physical change and the chemical change, what can you conclude about changes in mass due to physical and chemical changes? Write a single statement below.

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