In a science demonstration, a teacher mixed zinc Zn with hydrogen chloride HCl in a flask and quickly attached a balloon over the mouth of the flask. Bubbles formed in the solution and the balloon inflated. What most likely occurred during this demonstration?
Answer
A
Either Zn or HCl , but not both, retained its identity.
B
Evaporation of one of the substances occurred.
C
One or more new substances formed.
D
The Zn and HCl both retained their identity.
Explanation
The bubbles and inflating balloon indicate that a gas formed when zinc reacted with hydrochloric acid. In this reaction, zinc and hydrochloric acid produce zinc chloride and hydrogen gas, so new substances formed. The correct choice is “One or more new substances formed.”
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