A match is lit and held under a cold piece of metal. The followin...

Question

A match is lit and held under a cold piece of metal. The following 
observations are made: (a) The match burns. (b) The metal gets 
warmer. (c) Water condenses on the metal. (d) Soot (carbon) is 
deposited on the metal. Which of these occurrences are due to 
physical changes, and which are due to chemical changes?

Accepted Answer

Hi everyone here we have a question asking us to classify the following as physical or chemical changes. A physical change. The composition does not change a chemical change. The composition does change. So we have a water condenses on the surface of a cold glass. When water is condensing, it is simply changing forms so we can, it's still water. So our composition is not changing. So that is a physical change. Rest forms on the surface of an iron nail. Once that rest forms, we can't get the iron back because the composition has changed because it is a chemical change. Black smoke rises when a candle is burned. When a candle is burned, the wick is being burned which is releasing that black smoke and its composition is changing to release that black smoke. So that is a chemical change. A drop of alcohol evaporates on a table. That is a physical change. Because the composition, it's not changing, its form is simply changing. It's going from a liquid to a gas. So that is a physical change. So these are our final answers. Thank you for watching. Bye.

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