Chemistry 161
Sample Quiz Chapters 1&2 KEY
Harold
Note: You have already received a significant figures/scientific notation sample quiz. The first ten
problems (20 points) will be of exactly the same type. The numbers will be changed to offend the
guilty (those who did not use the sample test as a study guide).
1. The term that refers to the reproducibility of a laboratory measurement is
a. precision. b. repeatability. c. accuracy. d. exactness. e. the number of S.F.
2. The distance between atoms is sometimes given in picometers where 1 pm is equivalent to 1 x 10-12
m. If the distance between the layers of carbon atoms in graphite is 3.35 x 10-8 cm, what is this
distance in picometers?
a. 0.335
b. 3.35
c. 335 d. 3,350 e. 335,000
3
3
-9
3
3. How many cubic meters equal one cubic millimeter?1 mm x(1m/1000mm) = 1 x 10 m
4. Liquid propane boils at -42°C. What is its boiling point on the Kelvin scale? The Farenheit scale?
273.15 + -42 = 231 K
(9/5 x -42) + 32 = -44°F
5. What is the volume in cm3 of a cylinder that has a height of 0.020 meter and a radius of 0.010
meter?
volume of a right cylinder given by V = πr2h
r = 0.010m h = 0.020m
V= π x (0.010m x100cm/m)2 x 0.020m x 100 cm/m
V = 6.2832 cm3
V = 6.3 cm3
6. How many scruples are there in 25.8 lb? Some equivalents that may be helpful are given below:
1.00 scruple = 20.0 grains
1.00 g = 15.4 grains
1.00 grain = 0.0648 g
1.00 lb = 453.6 g
1.00 kg = 2.205 lb
25.8 lb x 453.6 g/lb x 15.4 grains/g x 1 scruple/ 20.0 grains = 9011.22 scruples = 9010 scruples
7. In 1928, 1.0 g of rhenium, Re, was isolated from 660 kg of the ore molybenite. Calculate the percent
by mass of this element in the molybenite ore.
(1.0 g x 1kg/1000g / 660 kg ) x 100 = 1.5 x 10-4 %
The first step is to convert the 1.0 gram to kg so I can set up the ratio of Re
recovered from the total mass of ore.
8. Calculate the mass of copper which occupies the same volume as 75.0 g of magnesium. The density
of Cu = 8.96 g/cm3 and Mg = 1.74 g/cm3 .
Two density eqn calculations: VMg = VCu = massMg/densityMg = 75.0g/1.74 g/cm3 = 43.1034 cm3
massCu = densityCu x VCu = 8.96 g/cm3 x 43.1034 cm3 = 386.2069 g = 386 g
9. An irregularly shaped metal was weighed by the following difference:
watch glass + metal = 56.7813 g
watch glass
= 35.4725 g
Mass of metal = 21.3088 g
The volume of the metal was determined by placing the metal in a graduated cylinder that had water in
it and measuring the volume difference.
21.3088g = 7.3479 g/mL = 7.35 g/mL
graduated cylinder + water + metal = 14.15 mL
graduated cylinder + water
= 11.25 mL
2.90 mL
calculate the density of the metal.
2.90 mL
10. The following species, 17Cl-, 18Ar, and 19K+, all have the same number of
Chemistry 161
a. protons.
Sample Quiz Chapters 1&2 KEY
b. electrons.
c. neutrons.
Harold
d. isotopes.
11. How many protons, neutrons, and electrons are in one atom of
e. nucleons.
119
50 p 69 n 50 e-
50Sn?
S2-
12. What is the symbol of the species that has 16 protons and 18 electrons?
13. An atom that has the same number of neutrons as
58
a. 59Ni.
b. 57Co.
c. 60Cu. d.
Fe.
59
Co is
e.
58
Ni.
59
Co has 59-27 = 32 n
14. A certain element is listed as having 72.6 atomic mass units. It is probably true that it contains
a. a mixture of isomers.
b. a mixture of allotropes.
c. a mixture of isotopes.
d. a mixture of enantiomers.
e. an impurity.
Since the mass is not a whole number then the total is likely composed of several isotopes
with varying mass numbers.
15. How many neutrons are there in 15 molecules of 3717Cl2 ?
2 37Cl in each molecule x (37 17) neutrons per 37Cl x 15 molecules Cl2 = 2 x 20 x 15 neutrons = 600 neutrons
16. What is the ratio of oxygen atoms to hydrogen atoms in the mineral carnotite, which has the
formula
K2(UO2)3(VO4)2 •3H2O?
a. 8:3
b. 8:6
c. 9:6
d. 17:3
e. 17:6
17. A series of hydrocarbons with the general formula, C n H2n+2, can be represented by the known
This best illustrates the law of
compounds CH4, C2H6, C3H8, C4H10, and C5H12.
a. conservation of mass.
b. conservation of charge.
c. definite composition.
d. multiple proportions. e. conservation of isotopes.
18. From the thermal decomposition of a pure solid, we obtained a solid and a gas, each of which is a
pure substance. From this information, we can conclude with certainty that
a. the original solid is not an element. b. at least one of the products is an element.
c. both products are elements.
d. the solid is a compound and the gas is an element.
e. the solid is an element and the gas is a compound.
Since the original was broken into simpler substances it cannot be an element. We have
no way of knowing what the two products are.
19. The formula for europium carbonate is Eu2(CO3)3. On the basis of this information, the formula for
the chlorate of europium would be expected to be?
a. EuCl2. b. EuCl3.
c. Eu2(ClO3)3.
d. Eu(ClO4)2.
e. Eu(ClO3)3.
CO3 has a 2- charge, therefore the Eu must have a 3+ charge. Since the
chlorate ion is 1-, we have a 1-3 ratio.
20. The elements in a row of the periodic table are known as
b. a group. c. metals. d. metalloids.
a. a family.
e. a period.
21. Which one of the following is true concerning the simplest unit of MgCl2(s)?
a. 1 Mg atom and 1 Cl2 molecule
b. 1 MgCl2 molecule
c. 1 Mg atom and 2 chlorine atoms
d. 1 positive ion and 2 negative ions
e. 1 positive and 1 negative ion
#21 This is an ionic compound, therefore it is composed of ions. It is not referred to as a molecule
and while it is composed of atoms theses atoms are in fact ions, so d. is the best answer.
Chemistry 161
Sample Quiz Chapters 1&2 KEY
22. Give the correct formula for the following ions:
a. phosphate ion
b. chlorate ion
c. nitrite ion
3-
PO4
-
Harold
d. phosphide ion
-
ClO3
P3-
NO2
23. Write the correct name for the following compounds.
a. Fe2S3 iron (III) sulfide b. CaF2 calcium fluoride c. Mn3(PO4)2 manganese (II) phosphate
d. K2C potassium carbide
e. Ca3N2 calcium nitride
Tb(SO4)2
24. Write the formula for terbium(IV) sulfate.
25. Write the formula for hypochlorous acid. What oxoanion is it composed of?
HClOthe hypochlorite ion
26. Write the name for the following compounds.
a. N2O4 dinitrogen tetroxide
b. XeF4 xenon tetrafluoride
c. Ca(HCO3)2 calcium bicarbonate or hydrogen carbonate
d. HClO4
perchloric acid
e. Nd2(SO4)3 neodymium (III) sulfate
28. Identify the following as to whether they are molecular or ionic compounds. If ionic write the
formula and names of the ions it is composed of.
a. Al2S3 ionic - Al3+ aluminum
S2sulfide
b. S2Cl2
molecular
c. (NH4)2CO3 ionic - NH4+ ammonium
e. NaCN
ionic - Na+ sodium
CO32-
carbonate
CN- cyanide
d. SF6 molecular