Pg 82-83 #9-19
9. Calculate the masses of water and sugar in a 55 g sugar solution that is labeled 20% sugar by mass.
a. 11 grams sugar
b. 44 grams water
b. 44 grams water
10. The EPA maximum standard for lead in drinking water is 0.015 mg/L. Express this value as parts per million (ppm).
a. .015 ppm of lead
11. What makes a water molecule polar?
a. What makes water a polar molecule is that it has an uneven distribution of electrical charge, which means that each molecule has a partial positive region at one end an a partial negative region at the other end.
12. Draw a model that shows how molecules in liquid water generally arrange themselves relative to one another.
13. Which region of a polar water molecule will be attracted to a
a. K+ ion: the oxygen, or negative, end
b. Br- ion: the hydrogen, or positive, end
14. Why are heavy metals called heavy?
a. Heavy metals are called heavy because their atoms have greater masses than those of essential metallic elements. They are also harmful to humans and other organisms.
15. List three symptoms of heavy-metal poisoning.
a. Three symptoms of heavy-metal poisoning are damage to the nervous system, brain, kidneys, and liver, which can even lead to death.
16. List two possible sources of human exposure to
a. Lead: pottery, automobile electrical storage batteries, solder, cooking vessels, pesticides, paints, and it used to be in pipes that travel to homes.
b. Mercury: medical and weather thermometers, thermostats, mercury-vapor street lamps, fluorescent light bulbs, and some paints. Elemental mercury can be absorbed directly through the skin. Some mercury vapor will always be present if liquid mercury is exposed to air.
17. What ion is found in many bases?
a. Hydroxide ions (OH-)
18. What element is found in most acids?
a. Hydrogen (H)
19. Classify each sample as acidic, basic, or chemically neutral:
a. Seawater (pH= 8.6): basic
b. Drain cleaner (pH= 13.0): basic
c. Vinegar (pH = 2.7): acidic
d. Pure water (pH=7.0): chemically neutral
No comments:
Post a Comment