Chapter 1, Problem 1.20E

How does an element differ from a compound? How are they similar?

Physical and Chemical Changes Say you are presented with two beakers, beaker A and beaker B, each containing a white, powdery compound. 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. b Would it be easier to prove that the compounds are the same or to prove that they are different? Explain your reasoning. c Which of the experiments that you listed above are the most convincing in determining whether the compounds are the same? Justify your answer. 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?

1.77 How can a liquid be distinguished from a fine powder? What type of experiment or observation might be undertaken?

Describe how the process offiltrationcould be used to separate a mixture into its components. Give an example.

Questions 47 and 48: Samples of matter may be classified in several ways, including gas, liquid, or solid G, L, S; pure substance or mixture P, M; homogenous or heterogeneous Hom, Het; and, for pure substances, element or compound E, C. For each substance in the left column of the tables shown, place in the other columns the symbol from the top of the column that best describes the substance in its most common state at room temperature and pressure. Assume that the material is clean and uncontaminated. The first box is filled in as an example. G, L, S P, M Hom, Het E, C Factory smokestack emissions All, but mostly G Concrete in a sidewalk Helium Hummingbird feeder solution Table salt

Questions 47 and 48: Samples of matter may be classified in several ways, including gas, liquid, or solid G, L, S; pure substance or mixture P, M; homogenous or heterogeneous Hom, Het; and, for pure substances, element or compound E, C. For each substance in the left column of the tables shown, place in the other columns the symbol from the top of the column that best describes the substance in its most common state at room temperature and pressure. Assume that the material is clean and uncontaminated. The first box is filled in as an example. G, L, S P, M Hom, Het E, C Limestone calcium carbonate Lead Freshly squeezed orange juice Oxygen Butter in the refrigerator

You receive a mixture of table salt and sand and have to separate the mixture into pure substances. Explain how you would carry out this task. Is your method based on physical or chemical properties? Explain.

In the left box, draw a particulate-level illustration of a substance in the gaseous state. Model the particles as spheres, which can be simple circles. Assume that the box represents a tiny, closed container that holds the particles. In the right box, draw a particulate-level illustration of the same substance after it cools and becomes a liquid

Analyses of several samples of a material containing only iron and oxygen gave the following results. Could this material be a compound?