Chapter 1, Problem 1.74AE

Rainwater comes from the oceans. Is rainwater more pure, less pure, or of the same purity as ocean water? Explain.

Which of the substances below are pure and which are mixtures? Which could be either? Explain your answers.

A solution made by dissolving sugar in water is homogeneous because the composition is the same everywhere. But if you could look with very high magnification, you would see locations with water particles and other locations with particles of sugar. How can we say that a sugar solution is homogenous?

Which of the following are elements, and which are compounds? a NaOH; b BaCl2; c He; d Ag; e Fe2O3.

Some ice cubes are homogeneous and some are heterogeneous. Into which group do ice cubes from your home refrigerator fall? If homogeneous ice cubes are floating on water in a glass, are the contents of the glass homogeneous or heterogeneous? Justify both answers.

Which of the following are the same and which are different? a. a substance and a pure substance b. a heterogeneous mixture and a solution c. a substance and a mixture d. a homogeneous mixture and a solution

Which of the following represent physical properties or changes, and which represent chemical properties or changes? You curl your hair with a curling iron. You curl your hair by getting a “permanent wave” at the hair salon. Ice on your sidewalk melts when you put salt on it. A glass of water evaporates overnight when it is left on the bedside table. Your steak chars if the skillet is too hot. Alcohol feels cool when it is spilled on the skin. Alcohol ignites when a flame is brought near it. Baking powder causes biscuits to rise.

Which of the following is a homogeneous mixture? a) water and sand b) water and salt c) water and cooking oil d) a hard-boiled egg

Consider the following separations of materials. State whether a physical process or a chemical reaction is involved in each separation. I. Sodium chloride is obtained from seawater by evaporation of the water. II. Mercury is obtained by heating the substance mercury (II) oxide; oxygen is also obtained. III. Pure water is obtained from ocean water by evaporating the water, then condensing it. IV. Iron is produced from an iron ore that contains the substance iron (III) oxide. V. Gold is obtained from river sand by panning (allowing the heavy metal to settle in flowing water).