Chapter 1, Problem 1.23QP

Physical and Chemical Changes

Say you are presented with two beakers, beaker A and beaker B, each containing a white, powdery compound.

1. a From your initial observations, you suspect that the two beakers contain the same compound. Describe, in general terms, some experiments in a laboratory that you could do to help prove or disprove that the beakers contain the same compound.
2. b Would it be easier to prove that the compounds are the same or to prove that they are different? Explain your reasoning.
3. c Which of the experiments that you listed above are the most convincing in determining whether the compounds are the same? Justify your answer.
4. d A friend states that the best experiment for determining whether the compounds are the same is to see if they both dissolve in water. He proceeds to take 10.0 g of each compound and places them in separate beakers, each containing 100 mL of water. Both compounds completely dissolve. He then states, “Since the same amount of both substances dissolved in the same volume of water, they must both have the same chemical composition.” Is he justified in making this claim? Why or why not?