Name:
Class Period:
Lab: Conservation of Mass
Introduction:
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Describe the law of conservation of mass.
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Write the chemical equation for the reaction and explain what the reactants and products will be in the lab
Mixing vinegar & baking soda to get sodium acetate, water and carbon dioxide
Reactants:__________
Products: ___________
Safety: (1pt)
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Goggles
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Glassware
Problem: (1 pt)
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How does the mass of several chemicals change when mixing a chemical reaction for a closed system?
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For an open system?
Hypothesis: (2 pts)
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Create a hypothesis answering your problem in and if… then statement
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“If the reaction is in a closed system then …”
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“If the reaction is in an open system then…”
Variables: (1 pt)
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IV: Type of system
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DV: Mass of the reaction
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Constants:
Materials:
__ 2 round bottom flasks
__ 1 balloon
__ Graduated cylinder
__ Digital Scale
__ Triple Beam Balance
__ 60 mL of Vinegar
__ 4 grams of Baking Soda
__ Weighing Dish
__ 1 Funnel
Part 1: Closed System:
1. Place an empty weighing dish on the scale.
2. Set the balance to zero on the scale.
3. Weigh out about 2 grams of baking soda in the weighing dish.
Baking Soda & Vinegar:
4. Remove the weighing dish from the scale and set the balance back to zero.
Closed System
5. Fill a round bottom flask with 30 mL of vinegar.
Starting mass: ___________ g
Ending mass: ____________ g
6. Set the balance to zero on the scale
Amount Changed: ________ g
7. Place flask on triple beam balance.
8. Place the funnel in the end of the balloon and pour the baking soda on the
weighing dish into the balloon.
9. Place the end of the balloon so it seals the opening of the flasks ***without pouring the baking soda into
the vinegar.(balloon should just flop over to the side)
10. Measure the mass of everything together on triple beam balance. RECORD as TOTAL MASS BEFORE RXN.
11. Lift up the balloon to mix the baking soda with vinegar. The balloon will fill with carbon dioxide.
12. RECORD the mass of the reaction under TOTAL MASS AFTER RXN.
13. RECORD the amount of change in the mass under AMOUNT OF MASS CHANGED.
Part 2: Open System:
1. Place an empty weighing dish on the scale.
Baking Soda & Vinegar:
2. Set the balance to zero on the scale.
Open System
Mass of Baking Soda: ___________ g
3. Weigh out about 2 grams of baking soda in the weighing dish.
Mass of Flask and Vinegar _______ g
4. Remove the weighing dish from the scale and set the balance
Total Mass before Reaction _________ g
back to zero.
Ending mass: ____________ g
5. Fill a round bottom flask with 30 mL of vinegar.
Amount Changed: ________ g
6. Place flask on triple beam balance to check that it is the same
as the closed system mass.
7. RECORD the as TOTAL MASS OF REACTANTS BEFORE RXN - OPEN.
8. (Find total mass before mixing and RECORD.)
9. Pour the baking soda into the flask.
10. Record the mass with the reaction under ENDING MASS.
11. RECORD the amount of change in the mass by finding the difference in the total mass before the reaction
and the ending mass after the reaction.
Substance
Mass
Observations
Vinegar – before mixing
Baking soda – before mixing
Total mass of reactants before
rxn - closed
Total mass of reactants before
rxn - open
Total mass of products in a
closed system
Total mass of products in an
open system
Amount of mass changed
Chemical Equation (Circle the reactants and box the products):
Vinegar + Baking Soda → Sodium Acetate + Water + Carbon Dioxide
Lab Questions:
Write down how you would explain the law of conservation of matter to someone not familiar with what it is.
What is the difference between an “open system” and a “closed system”?
Compare part 1, the closed system, to part 2, the open system.
What was the same?
What was different?