A student mixes vinegar (acetic acid) with baking soda (sodium bicarbonate), observes bubbling, then heats the resulting solution until a white solid forms. How many chemical changes occurred in this scenario?

• A. Two
• B. One
• C. Three
• D. Four

Answer: (A)

Verified step by step guidance

1. Identify the initial substances involved: vinegar (acetic acid, CH\_3COOH) and baking soda (sodium bicarbonate, NaHCO\_3).
2. Recognize the first chemical change: when vinegar and baking soda react, they undergo an acid-base reaction producing carbon dioxide gas (CO\_2), water (H\_2O), and sodium acetate (CH\_3COONa). The bubbling observed is due to the release of CO\_2 gas.
3. Understand that the formation of gas bubbles indicates a chemical change because new substances are formed and gas is released.
4. Next, consider the heating step: heating the resulting solution causes further chemical changes, such as the decomposition or crystallization of substances, leading to the formation of a white solid.
5. Conclude that there are two distinct chemical changes: the acid-base reaction producing gas and the subsequent heating causing the formation of a solid, so the total number of chemical changes is two.