Question

Mary Sue is making caramel ice cream. In the first part of the process, she combines a cup of sugar and a cup of water in a saucepan. She cooks the mixture over medium heat until the sugar melts and browns to a light amber color. Then she adds the same amount of water to the mixture along with a cup and a half of cream and milk. Which part of the preparation indicated a chemical change? A. adding cream and milk to the mixture B. mixing the sugar with water C. melting the sugar D. sugar changes from white to a light amber color

Answer 1

D. sugar changes from white to a light amber color We're looking for a chemical change. So let's examine the options and see what happening with them. A. adding cream and milk to the mixture She's just making a mixture here. No unexpected reactions or changes happen as she adds the cream and milk. So this is the wrong answer. B. mixing the sugar with water Dissolving the sugar in water. Once again, nothing unusual happens and if she were to evaporate the water, she'd be left with the original sugar. So this is the wrong answer. C. melting the sugar Just starting a simple phase change. Once again, no the right answer. D. sugar changes from white to a light amber color She's melted the sugar and has a clear fluid. As she continued to heat this fluid, it suddenly turns light amber. She has made a permanent change to the substance that she can't undo by simply physical means. She has converted part of the sugar into caramel. So a chemical change has happened here.