Question

Mrs. Smith is demonstrating a chemical change for her class. She places 15 grams of baking soda into a beaker. Next she adds 15 grams of vinegar to the same beaker. When the two compounds make contact, they bubble and fizz a great deal. She places the beaker on the balance and notes that the mass of the solution in the beaker is less than the expected 30 grams. Why is the mass of the solution in the beaker less than 30 grams? A) The balance was not working correctly. B) The gas that was released changed the mass. C) Mass is always lost in a chemical reaction. D) The new products have less mass than the original reactants.

Answer 1

Answer:

B) The gas that was released changed the mass.

Explanation:

In the acid base reaction of vinegar and sodium bicarbonate, sodium acetate, water and carbon dioxide are formed.

$C_{2}H_{4} O_{2}+NaHCO_{3}$  → $NaC_{2} H_{3}O_{2} +H_{2} O+CO_{2}$↑

Carbon dioxide is released from the beaker in the form of gas (as can be seen in the previous reaction), which is due to the loss of mass observed. This compound is responsible for the formation of bubbles in the reaction.

Answer 2

According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.

∴ B is the Answer