Name _________________________________________
Pd ____
Date ______________________
Honors Chemistry: Conservation of Matter Investigation
You will work as a lab group to complete this investigation. However, each student will submit his or her own
informal lab report, which consists of this handout.
Background
A chemical reaction occurs when matter undergoes a chemical change. One or more initial substances called
reactants change (aka react) to form one or more new substances called products. When acetic acid and sodium
bicarbonate come in contact with each other they change (aka react) to form three new substances, sodium
acetate, water and carbon dioxide. The chemical equation below documents the change:
CH3COOH + NaHCO3  NaCH3COO + H2O + CO2
What happens to the matter when it undergoes a change like this? Does some of it get lost or destroyed? Is new
matter created? Since mass is a measure of how much matter is in a substance, we can answer these questions
by measuring what happens to the mass of the reactants and products (aka the system).
In the above reaction a liquid (acetic acid) and a dissolved solid (sodium bicarbonate) react to create a liquid
(water) and a gas (carbon dioxide). We know that liquids and dissolved solids have mass and will stay at the
bottom of an open beaker. However, most gasses, like carbon dioxide, escape from an open container. Does this
mean gasses have no mass? If gasses have no mass does it mean they are not matter, or are they a special type of
massless matter? You’ll answer these questions with a short experiment.
Research Questions
1. How does a chemical reaction affect the total mass of a system?
2. Does all matter, including gasses, have mass?
Hypotheses - Use your previous knowledge to predict and explain your answers for each of the research questions.
Hypothesis #1 –
Hypothesis #2 -
Equipment & Materials
 digital balance
 graduated cylinder


5% acetic acid
sodium bicarbonate

plastic bottle with cap
Procedure
1. Using a graduated cylinder and funnel, pour about 100 mL of 5% acetic acid into an empty soda bottle.
2. Using a digital balance and weighing boat, pour about 5 grams of sodium bicarbonate into the soda bottle.
NOTE: Steps #3 and #4 need to happen within one to two seconds of step #2.
3. Immediately screw the cap on tightly, gently turn the bottle upside down to dissolve all the powder.
4. Place the bottle on the digital scale and record the mass every 30 seconds until the bubbles stop forming.
5. Once the bubbles have stopped, take the cap off the bottle and gently squeeze as much of the gas out of the
bottle without losing any of the liquid. Record the mass of the bottle, its contents, and the cap.
Data
Table 1 – The Total Mass of the Reactants and
Products During a Chemical Reaction
Time, s
Table 2 – The Mass of Carbon Dioxide Gas
Mass of the Cap,
Bottle & Contents, g
Total Mass, g
At the end of the reaction
After opening the bottle
and squeezing out the CO2
Conclusions - Answer the following research questions using your data to support your answer.
1. How does a chemical reaction affect the total mass of a system?
2. What is the mass of the carbon dioxide? (show your work with proper sig figs and units)
3. Does all matter, including gasses, have mass? Explain.
4. Challenge: Why does the carbon dioxide escape from an open container?