Which statement best describes chemical properties of matter?
Jenna took an open bowl of leftover mashed potatoes from the refrigerator and noticed a difference in smell. She determined that chemical changes occurred since the potatoes were first placed there.
Henry mixed salt and water together in a cup until he observed a clear solution. He measured the mass of the solution. Then he placed the cup outside for several sunny days during the summer. After a week, he observed that only solid salt remained in the cup and the mass had decreased. Henry concluded that a physical and chemical change occurred in this investigation.
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.
Investigations were carried out in a science lab to explore the topic of chemical and physical changes.Investigation AStep 1. Add 5 tsp. salt to 100 ml warm water and stir until most or all of the salt is no longer visible.Step 2. Heat the salt solution on a burner until only a white solid remains.Investigation BStep 1. Mix 10 tsp. white sugar into 100 ml water and stir until most or all of the sugar is no longer visible.Step 2. Heat the sugar solution on a burner until the solution thickens and turns brown.
Which event always involves a chemical change?
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