CHE-120 Homework chapter 1-3
Chapter 1
1.2, 1.4, 1.6, 1.8, 1.12, 1.14, 1.16, 1.22, 1.24, 1.26, 1.34, 1.36, 1.38, 1.42, 1.44, 1.52, 1.54,
1.66.
Answers:
1.2 a. I rode my bicycle for 15 miles today; b. My dog weighs 25 kilograms; c. It is hot
today. It is 30°C; d. I lost 1.5 pounds last week.
1.4 a. liter (used to measure volume); b. meter (length); c. kilogram (mass); d. gram
(mass); e. Kelvin (temperature).
1.6 a. 1.8 x 108 g; b. 6 x10-5 m; c. 7.5 x 105 g; d. 1.5 x 10-1 m; e. 2.4 x 10-4 kg.
1.8 a. exact; b. measured; c. measured; d. measured.
1.12 a. four; b. six; c. three; d. three; e. three; f. two.
1.14 The whole number would not reflect the precision (significant figures) allowed by
the original data without the additional zero.
1.16 a. 1.9; b. 180; c. 0.0047; d. 8800; e. 1.8.
1.22 You are not exceeding the 55 mph speed limit if your speedometer reads 80 kph.
1.24 Because the prefix centi means one hundredth, a centimeter is one hundredth of a
meter.
1.26 a. centimeter; b. kilogram; c. deciliter; d. gigameter; e. microgram.
1.34 Verify that the units cancel when the conversion factors are applied.
1.36
1.38 The new (desired) unit should be in the numerator of the conversion factor.
1.42
1.44
1.52
1.54
Chapter 2
2.4, 2.6, 2.10, 2.14, 2.26, 2.32, 2.34, 2.38.
2.4 a. potential; b. potential; c. kinetic; d. kinetic.
2.6 a. 8100 cal; b. 0.325 kJ; c. 10.7 kJ; d. 10 500 J
2.10
2.14
2.26 a. liquid; b. gas; c. gas.
2.32 a. boiling; b. condensation; c. evaporation; d. boiling.
2.34 a. The liquid absorbs heat from the skin to evaporate, thus the skin is chilled
(numbed).
b. In a wide dish, there are more molecules at the surface from which evaporation must
occur. The number of molecules with sufficient energy to evaporate and in
position to evaporate is greater in the wide dish, so the water evaporates faster
than it can in a tall glass.
2.38
Chapter 3
3.6, 3.12, 3.14, 3.16, 3.20, 3.22, 3.26, 3.36, 3.42, 3.48, 3.50, 3.56, 3.60, 3.64, 3.66, 3.70
3.6 a. homogeneous; b. heterogeneous; c. homogeneous; d. heterogeneous.
3.12 a. sodium and chlorine; b. calcium, sulfur, and oxygen; c. carbon, hydrogen,
chlorine, nitrogen, and oxygen; d. calcium, carbon, and oxygen.
3.14 a. Group 1A (1); b. Period 2; c. Group 8A (18); d. Group 7A (17)
3.16 a. noble gas; b. alkaline earth metal; c. transition element; d. halogen; e. alkaline
earth metal.
3.20 a. metal; b. metal; c. nonmetal; d. metalloid; e. nonmetal; f. nonmetal; g. nonmetal;
h. metal.
3.22 a. neutron; b. proton and neutron; c. electron; d. electron.
3.26 Selections a (two protons) and c (two electrons) are pairs of particles having the
same charge.
3.36
a. 8438Sr, 8638Sr, 8738Sr, 8838Sr
b. They all have the same atomic number (the same number of protons and
electrons).
c. They have different numbers of neutrons, which is reflected in their mass
numbers.
d. The atomic mass of sulfur on the periodic table is the average atomic mass of
all the naturally occurring isotopic masses.
3.48 a. 2, 8, 5; b. 2, 8; c. 2, 6; d. 2, 8, 8; e. 2, 8, 3; f. 2, 8, 4.
3.50 a. N; b. S; c. C;d. Ar; e. Al.
3.56 a. 2e-, Group 2A(2); b. 7e–, Group 7A(17); c. 6e–, Group 6A(16); d. 5e–, Group
5A(15); e. 2e–, Group 2A(2); f. 7e–, Group 7A(17).
3.60
3.42
3.64 Halogens are members of Group 7A(17), and each has seven valence electrons.
3.66 a. P, S, Cl; b. Ge, Si, C; c. Ba, Sr, Ca; d. Se, S, O.
3.70 a. C, O, N; b. S, P, Cl; c. As, P, N; d. Al, Si, P.