Question

there are four sketches below. the first sketch shows a sample of substance x. the three sketches underneath it show three different changes to the sample. you must decide whether each of these changes is possible. if a change is possible, you must also decide whether it is a physical change or a chemical change. each sketch is drawn as if the sample were under a microscope so powerful that individual atoms could be seen. also, you should assume that you can see the entire sample, and that the sample is in a sealed box, so that no matter can enter or leave.

Explanation:

Step1: Analyze Change 1

The molecules in Change 1 have the same structure as in the original sample of Substance X. Only the number of molecules has increased. Since no new substances are formed and the molecular structure remains the same, it is a physical change.

Step2: Analyze Change 2

The molecules in Change 2 have a different structure from the original Substance X. New - shaped molecules are formed, which means a chemical reaction has occurred to break and form new chemical bonds. So it is a chemical change.

Step3: Analyze Change 3

The sample is in a sealed box with no matter entering or leaving. In Change 3, the amount of matter seems to have increased which violates the law of conservation of mass. So it is impossible.

Answer:

Change 1: a physical change
Change 2: a chemical change
Change 3: impossible