Question

In the Copper Plating Solution lab, you placed copper (Cu) pennies in vinegar. Vinegar is a weak acid with hydrogen ions (H+). When you put the pennies in the vinegar, you should have observed small gas bubbles. What were these bubbles composed of, and how did they form

Answer 1

Bubbles came off from the copper pennies are hydrogen gas. There many free hydrogen ions in an acid like vinegar. And because of the chemical reaction between the copper and the vinegar, many hydrogen ions joined together to form hydrogen gas.