NEW
Font size
WorksheetsSDSMT - Chem 112 -Exam 4
Total questions: 27
Worksheet time: 14mins
What is the mass percentage of O in C4H9O2?
10.12%
21.90%
35.93%
55.15%
53.95%
What is the mass in grams of 0.852 moles of ferric oxide, Fe2O3 (formula mass = 159.69 amu)?
159 g
136 g
5.34 x 10-3 g
102 g
187 g
A 130.3 g piece of copper (specific heat 0.380 J/g °C) is heated and then placed into 400.0 g of water
initially at 20.7 °C. The water increases in temperature to 22.2 °C. What is the initial temperature (in
°C) of the copper? (The specific heat of water is 4.184 J/g °C).
72.9 °C
19.7 °C
71.4 °C
74.4 °C
50.7 °C
If you have 5 mol H2 and 2 mol N2, what is the limiting reagent in the reaction below?
3 H2(g) + N2 (g) --> 2 NH3 (g)
N2
NH3
No reactant is limiting.
Both reactants are limiting
H2
In this reaction: Mg (s) + I2 (s) -> MgI2 (s),
if 10.0 g of Mg reacts with 60.0 g of I2, and 57.84 g of MgI2 form, what is the percent yield?
71.8%
92.5%
49.2%
100%
88.1%
What is the molar mass of potassium nitrate?
56.11 g/mol
120.36 g/mol
72.63 g/mol
101.10 g/mol
85.47 g/mol
What is the final temperature (in °C) of 150.1 g of water (specific heat = 4.184 J/g °C) at 24.20 °C
that absorbed 950.0 J of heat?
25.71 °C
27.23 °C
-25.71 °C
-22.68 °C
22.68 °C
If 250.3 L of hydrogen gas (d = 0.0899 g/L) reacts with an excess of nitrogen gas, what mass of
ammonia would be produced?
3 H2 (g) + N2 (g) --> 2 NH3 (g)
127 g
255 g
253 g
380 g
420 g
How many moles are in 1770 g of cuprous sulfate, Cu2SO4 (formula mass = 223.15 amu)?
3.97 moles
395 moles
7.93 moles
7.93 x 10-3 moles
223 moles
Which one of the following contains the most moles of oxygen atoms?
1 mol of Fe(C2H3O2)3
5 mol of H2O
3 mol of CH3OH
2 mol of Ca(NO2)2
1 mol of Na3PO4
A chemical reaction that gives off energy in the form of heat is considered _____.
non-spontanenous
exothermic
spontaneous
exergonic
endothermic
A reaction where the products are higher in energy than the reactants is an example of an _____.
exergonic process
endothermic process
Not enough information
isothermal process
exothermic process
If 35.0 g of CH3OH (molecular mass 32.0 amu) are dissolved in 500.0 mL of solution, what is the
concentration of CH3OH in the solution?
2.19 M
0.00218 M
2.50 M
0.458 M
0.0700 M
How many moles of HCl are needed to completely react with 50.0 mL of 0.250 M NaOH solution?
Hint: Write a balanced equation for the reaction first
2.50 moles
2.50 x 10-1 moles
1.25 x 101 moles
1.25 x 10-2 moles
1.25 moles
A 21.8 g sample of water (H2O) contains how many water molecules?
2.18 x 1023 molecules
1.80 x 1024 molecules
6.02 x 1023 molecules
2.01 x 10-24 molecules
7.29 x 1023 molecules
A 0.125 g sample of unknown hydrocarbon is prepared for combustion analysis. After the
hydrocarbon undergoes complete combustion, 0.4225 g of CO2 and 0.0865 g of H2O are produced.
What is the empirical formula of the unknown?
C2H3
CH3
CH4
CH
CH2
Which of the following measures the average kinetic energy of a system?
enthalpy
specific heat capacity
temperature
internal energy
heat
A _____ is an experimental set-up that can be used to measure the heat of a chemical reaction or a
physical change and determine the specific heat capacity of a substance.
calorimeter
thermometer
spectrometer
manometer
barometer
What is the change in enthalpy when 2.5 moles of H2 are reacted with an excess O2 according to the
following balanced chemical reaction:
2 H2 (g) + O2 (g) --> 2 H2O (l) ΔH° = -572 kJ
+358 kJ
+572 kJ
-715 kJ
-1430 kJ
-358 kJ
Ozone, O3, is a product in automobile exhaust by the reaction represented by the equation
NO2(g) + O2(g)--> NO(g) + O3(g).
What mass of ozone is predicted to form from the reaction of 2.0 g NO2 in a car’s exhaust and excess
oxygen?
1.1 g O3
1.8 g O3
2.2 g O3
2.1 g O3
1.30 g O3
For the following combustion reaction
C6H5OH(s) + 7O2(g) --> 6CO2(g) + 3H2O(g) ΔH° = -3.05 × 10³ kJ
When a 4.05-g sample of phenol (C6H5OH, formula mass = 70.09 amu) is burned, how much energy
(in kJ) is released as heat?
176 kJ
88 kJ
528 kJ
352 kJ
The energy is absorbed, because the
enthalpy is negative
25.0 mL of a 0.350 M solution of K2MnO4 is diluted to 60.0 mL. What is the new concentration of the
solution?
0.00400 M
0.146 M
0.840 M
0.525 M
4.285 M
Using the enthalpies of formation provided below, determine the enthalpy of the reaction
(in kJ) for the reaction
2 K(s) + 2 H2O(l) -> 2 KOH (aq) + H2(g)
ΔHf° (H2O (l)) = -285.8 kJ/mol
ΔHf° (KOH (aq)) = -482.4 kJ/mol
+196.6 kJ
-393.2 kJ
-196.6 kJ
0 kJ
+393.2 kJ
What is the molecular formula of a compound that contains only carbon and hydrogen, is 85.7%
carbon by mass, and has a molar mass of 140 g/mol?
C9H32
C12H24
C8H24
C10H20
CH2
Using the equations
2 Fe (s) + 3 Cl2 (g) --> 2 FeCl3 (s) ΔH° = -800.0 kJ
Si(s) + 2 Cl2 (g) --> SiCl4 (s) ΔH° = -640.1 kJ
Determine the enthalpy of the reaction (in kJ) for the reaction
3 SiCl4 (s) + 4 Fe (s) -> 4 FeCl3 (s) + 3 Si (s)
-319.8 kJ
+159.9 kJ
-320.3 kJ
+320.3 kJ
-159.9 kJ
If a system does 84.0 kJ of work on its surroundings and releases 105 kJ of heat, what is the change in
the internal energy of the system, in kJ?
0.0
84.0
-21.0
105.0
21.0
Which one of the equations below is an exothermic reaction?
N2 (g) + O2 (g)
--> 2 NO (g)
ΔH° = 180.6 kJ
CO2 (g) -->
C (s) + O2 (g)
ΔH° = 394 kJ
H2 (g) + C (s) + N2 (g) --> 2 HCN (g) ΔH° = 270.3 kJ
CaO (s) + H2O (l)
--> Ca(OH)2 (aq) ΔH° = -64 kJ
C (s) + 2 F2 (g)
--> CF4 (g)
ΔH° = 141.3 kJ
