Chemistry Combination Reactions Questions

1) Which of the following are combination reactions?
1) CH4 (g) + O2 (g) → CO2 (g) + H2O (l)
2) CaO (s) + CO2 (g) → CaCO3 (s)
3) Mg (s) + O2(g) → MgO (s)
4) PbCO3 (s) → PbO (s) + CO2 (g)
A) 1, 2, and 3
B) 2 and 3
C) 1, 2, 3, and 4
D) 4 only
E) 2, 3, and 4
2) What is the physical state in which matter has a definite volume and a definite shape?
A) gas
B) solid
C) liquid
D) salts
E) ice
3) A small amount of salt dissolved in water is an example of a
A) homogeneous mixture
B) heterogeneous mixture
C) compound
D) pure substance
E) solid
.
4) The law of constant composition says
.
A) that the composition of a compound is always the same
B) that all substances have the same composition
C) that the composition of an element is always the same
D) that the composition of a homogeneous mixture is always the same
E) that the composition of a heterogeneous mixture is always the same
5) In the following list, only
is not an example of a chemical reaction.
A) dissolution of a penny in nitric acid
B) the condensation of water vapor
C) a burning candle
D) the formation of polyethylene from ethylene
E) the rusting of iron
Page 1 of 8
6) Based on the activity series, which one of the reactions below will occur?
A) Fe (s) + ZnCl2 (aq) → FeCl2 (aq) + Zn (s)
B) Mn (s) + NiCl2 (aq) → MnCl2 (aq) + Ni (s)
C) Pb (s) + NiI2 (aq) → PbI2 (aq) + Ni (s)
D) SnBr2 (aq) + Cu (s) → CuBr2 (aq) + Sn (s)
E) None of the reactions will occur.
7) What volume (mL) of a concentrated solution of magnesium chloride (9.00 M) must be
diluted to 350. mL to make a 2.75 M solution of magnesium chloride?
A) 14.1
B) 1.15
C) 127
D) 107
E) 38.8
8) Which one of the following is the highest temperature?
A) 38 °C
B) 96 °F
C) 302 K
D) none of the above
E) the freezing point of water
9) The number 0.0101 has
A) 2
B) 3
C) 5
D) 4
E) 6
significant figures.
10) The specific heat capacity of lead is 0.13 J/g-K. How much heat (in J) is required to raise the
temperature of
of lead from 22 °C to 37 °C?
A) 2.0 J
B) -0.13 J
C) 5.8 × 10-4 J
D) 29 J
E) 0.13 J
11) Isotopes are atoms that have the same
A) atomic masses, charges
B) mass numbers, atomic numbers
C) atomic numbers, mass numbers
D) charges, atomic masses
E) mass numbers, charges
but differing
_.
Page 2 of 8
12) Element X has three naturally occurring isotopes. The masses (amu) and % abundances of
the isotopes are given in the table below. The average atomic mass of the element is
amu.
A) 41.54
B) 39.68
C) 39.07
D) 38.64
E) 33.33
13) The value of ΔH° for the reaction below is -6535 kJ.
combustion of 16.0 g of
(l)?
2C6H6 (l) + 15O2 (g) → 12CO2 (g) + 6H2O (l)
kJ of heat are released in the
A) 1.34 × 103
B) 5.23 × 104
C) 669
D) 2.68 × 103
E) -6535
14) Of the species below, only
A) HBr
B) LiCl
C) Ne
D) KOH
E) NaNO3
15) A
ΔH corresponds to an
A) negative, endothermic
B) negative, exothermic
C) positive, exothermic
D) zero, exothermic
E) zero, endothermic
is not an electrolyte.
process.
Page 3 of 8
16) The value of ΔE for a system that performs 19 kJ of work on its surroundings and loses
of heat is
A) -28
B) 28
C) 171
D) 10
E) -10
17) Which pair of elements would you expect to exhibit the greatest similarity in their physical
and chemical properties?
A) As, Br
B) Mg, Al
C) I, Br
D) Br, Kr
E) N, O
18) Which compounds do not have the same empirical formula?
A) C2H2, C6H6
B) CO, CO2
C) C2H4, C3H6
D) C2H4O2, C6H12O6
E) C2H5COOCH3, CH3CHO
19) Barium reacts with a polyatomic ion to form a compound with the general formula Ba3(X)2.
What would be the most likely formula for the compound formed between sodium and the
polyatomic ion X?
A) NaX
B) Na2X
C) Na2X2
D) Na3X
E) Na3X2
20) A slice of cake contains 29.0 grams of fat, 9.0 grams of protein, and 77 grams of carbohydrate.
If swimming burns 1000.0 kJ/hour, how many minutes would it take to completely burn off the
slice of cake? The respective fuel values for protein, fat, and carbohydrate are 17, 38, and 17 kJ/g,
respectively.
A) 154
B) 2.56
C) 23.4
D) 117
E) 262
Page 4 of 8
21) The correct name for Ca(OH)2 is
A) monocalcium dioxygen dihydrogen
B) calcium dihydroxide
C) calcium oxide hydride
D) calcium bihydroxide
E) calcium hydroxide
.
22) Elements in Group 7A are known as the
A) chalcogens
B) alkali metals
C) alkaline earth metals
D) halogens
E) noble gases
.
23) Which combination will produce a precipitate?
A) NaC2H3O2 (aq) and HCl (aq)
B) NaOH (aq) and HCl (aq)
C) AgNO3(aq) and Ca(C2H3O2)2 (aq)
D) KOH (aq) and Mg(NO3)2 (aq)
E) NaF (aq) and HCl (aq)
24) The net ionic equation for the reaction between aqueous nitric acid and aqueous sodium
hydroxide is
.
+
A) H (aq) + HNO3 (aq) + 2OH- (aq) → 2H2O (l) + NO3- (aq)
B) HNO3 (aq) + NaOH (aq) → NaNO3 (aq) + H2O (l)
C) H+ (aq) + OH- (aq) → H2O (l)
D) HNO3 (aq) + OH- (aq) → NO3- (aq) + H2O (l)
E) H+ (aq) + Na+ (aq) + OH- (aq) → H2O (l) + Na+ (aq)
25) Which compound has the atom with the highest oxidation number?
A) CaS
B) Na3N
C) MgSO3
D) Al(NO2)3
E) NH4Cl
26) When a metal and a nonmetal react, the
tends to gain electrons.
A) metal, metal
B) nonmetal, nonmetal
C) metal, nonmetal
D) nonmetal, metal
tends to lose electrons and the
Page 5 of 8
E) None of the above; these elements share electrons.
27) The formula of ammonium carbonate is
A) (NH4)2CO3
B) NH4CO2
C) (NH3)2CO4
D) (NH3)2CO3
E) N2(CO3)3
.
28) What is the empirical formula of a compound that contains 49.4% K, 20.3% S, and 30.3% O
by mass?
A) KSO2
B) KSO3
C) K2SO4
D) K2SO3
E) KSO4
29) Which one of the following compounds is insoluble in water?
A) K2SO4
B) Ca(C2H3O2)2
C) MgC2O4
D) ZnCl2
E) Mn(NO3)2
30) A compound that is composed of carbon, hydrogen, and oxygen contains 70.6% C, 5.9% H,
and 23.5% O by mass. The molecular weight of the compound is 136 amu. What is the molecular
formula?
A) C8H8O2
B) C8H4O
C) C4H4O
D) C9H12O
E) C5H6O2
Page 6 of 8
I.
Problems (55 points total) (Please show your work for calculation problems.
Remember to check your significant figures.)
1) (3 pts) Iron has a density of 7.9 g/cm3. What is the mass of a cube of iron with the length
of one side equal to 55.0 mm?
Page 7 of 8
2) (3 pts) There are _____protons,
neutrons, and
electrons in 131I-.
3) (4 pts) A 650 mL sodium bromide solution has a bromide ion concentration of 0.245 M.
What is the mass (g) of sodium bromide in solution?
4) (4 pts) Label the following compounds as ionic or molecular.
a) SO2
ionic / molecular
b) Dichlorine monoxide
ionic / molecular
c) Barium bromide
ionic / molecular
d) CaCl2
ionic / molecular
5) (4 pts) Given the data in the table below, ΔH°rxn for the
reaction C2H5OH (l) + O2 (g) → CH3CO2H (l) +
H2O (l)
is
kJ.
Page 8 of 8
6) (2 pts) The correct name for H2SO4 is
.
7) (4 pts) How many milliliters of 0.188 M HClO4 solution are needed to neutralize
50.00 mL of 0.0832 M NaOH?
Page 9 of 8
8) (3 pts) Given the following reactions
N2 (g) + 2O2 (g) → 2NO2 (g) ΔH = 66.4 kJ
2NO (g) + O2 (g) → 2NO2 (g) ΔH = -114.2 kJ
the enthalpy of the reaction of the nitrogen to produce nitric oxide
N2 (g) + O2 (g) → 2NO (g)
is
kJ.
9) (3 pts) What is the percentage by mass of carbon in CO2?
10) (3 pts) How many oxygen atoms are contained in 2.74 g of Al2(SO4)3?
11) (2 pts) When the following equation is balanced, the coefficient of H2 is _.
K (s) + H2O (l) → KOH (aq) + H2 (g)
Page 10 of
8
12) (2 pts) There are
molecules of methane in 0.123 mol of methane (CH4).
13) (8 pts) Hydrogen (H2) gas is produced by the reaction of 31.3 g of magnesium with 2.12 g
of water Mg (s) + 2H2O (l) → Mg(OH)2 (s) + H2 (g)
What is the theoretical yield in grams for H2?
If the yield of H2 is 0.085 g, what is the percent yield?
Page 11 of
8