MINILAB 12.2 Bagging the Gas

Chemists and chemical engineers often need to determine amounts of reactants and products that will react efficiently and cost effectively. Use the molar volume to determine the amount of baking soda required to react with vinegar to yield just enough carbon dioxide to fill a one-quart, self-sealing plastic bag.

PURPOSE: TO DETERMINE THE AMOUNT OF BAKING SODA THAT YIELDS ONE QUART OF CARBON DIOXIDE WHEN REACTED WITH EXCESS VINEGAR.

HYPOTHESIS:

MATERIALS: SELF-SEALING PLASTIC BAG, baking soda (sodium hydrogen carbonate), vinegar (acetic acid), water, graduated cylinder, plastic-coated twist tie, explosion shield, BALANCE

PROCEDURE

1. Write the balanced equation for the reaction of baking soda (sodium hydrogen carbonate) and vinegar (acetic acid) that produces sodium acetate, water, and carbon dioxide.

2. Find the volume of a 1-quart, self-sealing plastic bag by filling it with water and then pouring the water into a graduated cylinder or measuring cup.

3. Calculate the mass of sodium hydrogen carbonate that will fill the bag with CO₂ gas when the compound reacts with excess acetic acid.

4. Put on an apron and goggles.

5. Weigh the calculated amount of sodium hydrogen carbonate and place it in a bottom corner of the bag. Use a plastic-coated twist tie to seal off this corner.

6. Pour about 60 mL of 1M acetic acid into the other bottom corner of the bag. Be careful not to allow the reactants to mix. Squeeze the air from the bag and seal the zipper top.

7. Place the bag in a large trash can or behind an explosion shield.

8. Release the twist tie, quickly mix the reactants, and allow the reaction to proceed to completion.

OBSERVATIONS:

BALANCED EQUATION:

VOLUME OF PLASTIC BAG:

CALCULATED MASS OF SODIUM HYDROGEN CARBONATE FROM REACTION:

BEFORE DRAWING OR DESCRIPTION AFTER DRAWING OR DESCRIPTION

ANALYSIS

1. Show and explain the calculations that you used to determine the required mass of sodium hydrogen carbonate.

2. What mass of sodium hydrogen carbonate would be required to react with excess acetic acid to produce 20 000 L of carbon dioxide gas at STP for a water treatment plant?

3. What would have happened in step 8 if the amount of acetic acid added were insufficient to react with all of the baking soda?

4. Suppose the pressure of the gas in the bag was measured to be 101.5 kPa. Is this pressure consistent with the ideal gas law? Assume T = 20 ^oC and P =115 kPa. EXPLAIN