Unit 3 Practice
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) The formula weight of a substance is __________.
A) determined by combustion analysis
B) identical to the molar mass
C) the sum of the atomic weights of each atom in its chemical formula
D) the weight of a sample of the substance
E) the same as the percent by mass weight
1)
2) The compound responsible for the characteristic smell of garlic is allicin, C6 H10OS2 . The mass of
2)
1.00 mol of allicin, rounded to the nearest integer, is __________ g.
A) 34
B) 61
C) 19
D) 162
3) Calculate the percentage by mass of nitrogen in PtCl2 (NH3 )2 .
A) 9.34
B) 4.67
C) 4.95
E) 86
3)
D) 12.67
E) 9.90
4) When a hydrocarbon burns in air, what component of air reacts?
A) argon
B) oxygen
C) water
D) carbon dioxide
E) nitrogen
4)
5) The formula weight of silver chromate (Ag2 CrO4 ) is __________ amu.
A) 159.87
B) 223.87
C) 175.87
D) 331.73
5)
E) 339.86
6) There are ________ oxygen atoms in 30 molecules of C20H42S3 O2
A) 1.8 x 1025
B) 1.2 x 1024
C) 6.0 x 1023
D) 3.6 x 1025
7) The formula weight of lead nitrate (Pb(NO3 )2) is __________ amu.
A) 317.2
B) 285.2
C) 538.4
8) Calculate the percentage by mass of nitrogen in Pb(NO3 )2 .
A) 8.5
B) 12.6
C) 5.2
9) Calculate the percentage by mass of oxygen in Pb(NO3 )2 .
A) 33.4
B) 9.7
C) 14.5
D) 269.2
D) 1.473 × 10-7
E) 2.945 × 10-7
1
E) 60
7)
E) 331.2
8)
D) 4.2
E) 10.4
9)
D) 19.3
10) How many moles of sodium carbonate contain 1.773 × 1017 carbon atoms?
A) 8.836 × 10-7
B) 9.817 × 10-8
C) 5.890 × 10-7
6)
E) 29.0
10)
11) Which one of the following substances is the product of this combination reaction?
Al (s) + I2 (s)
A) Al3 I2
__________
B) AlI2
D) Al2 I3
C) AlI
12) A 30.5 gram sample of glucose (C6 H12O6 ) contains __________ mol of glucose.
A) 0.424
B) 0.169
C) 2.36
D) 0.136
13) The mass % of H in methane (CH4 ) is __________.
A) 25.13
11)
B) 4.032
E) AlI3
12)
E) 5.90
13)
C) 92.26
D) 7.743
E) 74.87
14) Of the reactions below, which one is not a combination reaction?
A) 2N2 + 3H2
2NH3
14)
B) 2CH4 + 4O2
2CO2 + 4H2 O
C) 2Mg + O2
2MgO
D) CaO + H2 O
Ca(OH)2
E) C + O2
CO2
15) The mass % of C in methane (CH4 ) is __________.
A) 92.26
B) 7.743
15)
C) 133.6
16) One mole of __________ contains the largest number of atoms.
A) Cl2
B) Al2 (SO4 )3
C) S8
D) 74.87
E) 25.13
D) Na3 PO4
E) C10H8
17) The formula weight of ammonium sulfate ((NH4 )2 SO4 ), rounded to the nearest integer, is
__________ amu.
A) 264
B) 116
C) 132
18) The mass % of F in the binary compound KrF2 is __________.
A) 45.38
B) 18.48
C) 31.20
D) 100
E) 118
D) 68.80
E) 81.52
16)
17)
18)
19) Of the reactions below, which one is not a combination reaction?
A) 2N2 + 3H2
2NH3
19)
B) 2Mg + O2
2MgO
C) CaO + H2 O
Ca(OH)2
D) C + O2
CO2
E) 2CH4 + 4O2
2CO2 + 4H2 O
20) Calculate the percentage by mass of lead in Pb(NO3 )2 .
A) 71.2
B) 62.6
C) 65.3
21) Calculate the percentage by mass of hydrogen in PtCl2 (NH3 )2 .
A) 0.672
B) 1.558
C) 2.016
2
20)
D) 38.6
E) 44.5
21)
D) 0.034
E) 1.008
22) What is the mass in grams of 9.76 × 1012 atoms of naturally occurring sodium?
A) 7.05 × 10-13
22)
B) 3.73 × 10-10
C) 2.24 × 1014
D) 22.99
E) 1.62 × 10-11
23) How many oxygen atoms are contained in 2.74 g of Al2 (SO4 )3 ?
23)
A) 5.79 × 1022
B) 6.02 × 1023
C) 7.22 × 1024
D) 12
E) 8.01 × 10-3
24) The total number of atoms in 0.111 mol of Fe(CO)3 (PH3 )2 is __________.
24)
A) 4.46 × 1021
B) 2.76 × 10-24
C) 1.00 × 1024
D) 15.0
E) 1.67
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
25) Under appropriate conditions, nitrogen and hydrogen undergo a combination reaction to
yield ammonia:
N2 (g) + 3H2 (g)
25)
2NH3 (g)
A 9.3-g sample of hydrogen requires __________ g of N2 for a complete reaction.
26) The combustion of carbon disulfide in the presence of excess oxygen yields carbon dioxide
and sulfur dioxide:
CS2 (g) + 3O2 (g)
26)
CO2 (g) + 2SO2 (g)
The combustion of 15 g of CS2 in the presence of excess oxygen yields __________ g of SO2 .
27) A compound was found to contain 90.6% lead (Pb) and 9.4% oxygen. The empirical
formula for this compound is __________.
27)
28) Water can be formed from the stoichiometric reaction of hydrogen with oxygen:
28)
2H2 (g) + O2 (g)
2H2 O (g)
A complete reaction of 5.0 g of O2 with excess hydrogen produces __________ g of H2 O.
3
29) The combustion of propane (C3 H8 ) in the presence of excess oxygen yields CO2 and H2 O:
C3 H8 (g) + 5O2 (g)
29)
3CO2 (g) + 4H2 O (g)
When 7.3 g of C3 H8 burns in the presence of excess O2 , __________ g of CO2 is produced.
30) Complete and balance the following reaction, given that elemental rubidium reacts with
elemental sulfur to form Rb2 S (s).
Na (s) + S (s)
__________
4
30)
Answer Key
Testname: UNTITLED1
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
12)
13)
14)
15)
16)
17)
18)
19)
20)
21)
22)
23)
24)
25)
26)
27)
C
D
A
B
D
E
E
A
E
E
E
B
A
B
D
E
C
C
E
B
C
B
A
C
43
25
Pb3 O4
28) 5.6
29) 22
30) Na2 S (s)
5