Lab: Physical and Chemical Changes

Question 5 • FL-2003350-Chemistry 1 Honors Sem 1 - Flex

Which answer below correctly identifies the type of change and the explanation when magnesium comes into contact with hydrochloric acid?

Answer

physical change because no color change occurred

physical change because the observation of a gas forming is evidence of a state change, which is reversible

chemical change because a temperature change occurred, a solid disappeared, and a gas was produced

chemical change because two substances were mixed, which always results in the formation of a new substance

Explanation

Magnesium reacts with hydrochloric acid to form new substances: magnesium chloride and hydrogen gas. The solid magnesium disappears and gas bubbles form, and the reaction can also cause a temperature change. These observations indicate a chemical change, so choice C is correct. Simply mixing two substances does not always produce a new substance, which makes D’s explanation incorrect.

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