Question

Meredith mixes together 5 grams of baking soda and 5 grams of vinegar in a test tube that is not sealed. She then weighs the product and finds that it weighs 9 grams. Mathew conducts the same experiment, except in a sealed bag. He finds that 5 grams of baking soda and 5 grams of vinegar will result in 10 grams of product. Which of the following might account for their different findings?
A.

Some of the mass from the test tube was destroyed.

B.

Some of the mass of the reactants was converted to light.

C.

Some of the mass escaped from the test tube as a gas before it was massed.

D
.

Some of the mass was created during the reaction between vinegar and baking soda in the bag.

Answer 1

C. Some of the mass escaped from the test tube as a gas before it was massed.

When vinegar (acetic acid) reacts with baking soda (sodium bicarbonate) it produces carbon dioxide gas. In the open test tube that CO2 could escape, so the remaining measured mass was lower. In the sealed bag the CO2 stayed inside, so total mass remained 10 g.