Base your answers
to questions 73 through 75 on the information below.
contains dissolved salts in the form of ions. Some of the ions found
in seawater are Ca2+, Mg2+, K+, Na+,
Cl-, HCO3-, and SO4
2-. An investigation was conducted to determine the
concentration of dissolved salts in seawater at one location. A
300.-gram sample of the seawater was placed in an open container.
After a week, all the water had evaporated and 10. grams of solid
salts remained in the container.
73 Determine the concentration, expressed as percent by mass, of
the dissolved salts in the original sample of seawater.  -
74 At standard pressure, compare the freezing point of
seawater to the freezing point of distilled water. 
|Answer==>Water has a higher
freezing point than seawater.
75 Explain why the evaporation that occurred during the
investigation is an endothermic process. 
|Answer==>Energy is required to
change liquid water to water vapor.