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WorksheetsHigher Chemistry Unit 3 MCQ Revision
Total questions: 25
Worksheet time: 19mins
A reaction has the potential energy diagram shown
The activation energy for the forward reaction is
X –Y
Y –X
Y –Z
Z –Y.
Which of the following statements regarding a chemical reaction at equilibrium is always correct?
The rates of the forward and reverse reactions are equal.
The concentration of reactants and products are equal.
The forward and reverse reactions have stopped.
The addition of a catalyst changes the position of the equilibrium.
Consider the reaction pathway shown.
According to Hess’s Law, the ΔH value, in kJ mol−1 , for reaction Z to Y is
+74
-74
+346
-346
The diagram shows the energy profiles for a reaction carried out with and without a catalyst. What is the enthalpy change, in kJ mol–1, for the catalysed reaction?
-100
-50
+50
+100
The mean bond enthalpy of a C – F bond is 484 kJ mol−1 . In which of the processes is ΔH approximately equal to +1936 kJ mol−1 ?
CF4(g) → C(s) + 2F2(g)
CF4(g) → C(g) + 4F(g)
CF4(g) → C(g) + 2F2(g)
CF4(g) → C(s) + 4F(g)
Which of the following equations represents the enthalpy of combustion of propane?
C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(ℓ)
C3H8(g) + 3.5O2(g) → 3CO(g) + 4H2O(ℓ)
C3H8(g) + 3O2(g) → 3CO2(g) + 4H2(g)
C3H8(g) + 1.5O2(g) → 3CO(g) + 4H2(g)
xP2H4 + yO2 → P4O10 + zH2O
The equation is balanced when
x = 1, y = 5, z = 4
x = 4, y = 6, z = 2
x = 2, y = 7, z = 4
x = 2, y = 5, z = 2
The atom economy for the production of titanium in the equation shown is equal to
The vitamin C content of a carton of orange juice was determined by four students. Each student carried out the experiment three times. The most reproducible results were obtained by
Student A
Student B
Student C
Student D
Bromine and hydrogen react together to form hydrogen bromide
H2(g) + Br2(g) → 2HBr(g)
-102
+102
-264
+264
Which line in the table best describes the effect of adding a catalyst to the following reaction?
4NH3(g) + 5O2(g) ⇌ 4NO(g) + 6H2O(g) ΔH = −ve
A
B
C
D
The potential energy diagram refers to the reversible reaction involving reactants R and products P.
What is the enthalpy change, in kJ mol−1 , for the reverse reaction?
-40
-10
+10
+30
The relative rate of a reaction which reached completion in 1 minute 40 seconds is
0·010 s−1
0·714 s−1
0·010 min−1
0·714 min−1
Which of the following is the correct interpretation of the energy distribution diagram for a reaction as the temperature decreases from T2 to T1?
activation energy increases
number of successful collisions decreases
number of successful collisions increases
activation energy decreases
A mixture of sodium chloride and sodium sulfate is known to contain 0∙6 mol of chloride ions and 0∙2 mol of sulfate ions. How many moles of sodium ions are present?
0.4
0.5
0.8
1
Under the same conditions of temperature and pressure, which of the following gases would occupy the largest volume?
0·20 g of hydrogen
0·44 g of carbon dioxide
0·60 g of neon
0·80 g of argon
3CuO + 2NH3 → 3Cu + N2 + 3H2O
What volume of gas, in cm3 , would be obtained by reaction between 100 cm3 of ammonia gas and excess copper(II) oxide?
All volumes are measured at atmospheric pressure and 20 °C
50
100
200
400
Cl2(g) + H2O(ℓ) ⇌ Cl− (aq) + ClO− (aq) + 2H+(aq )
The addition of which of the following substances would move the above equilibrium to the right?
hydrogen
hydrogen chloride
sodium chloride
sodium hydroxide
When 3·6 g of butanal (mass of one mole = 72 g) was burned, 124 kJ of energy was released. What is the enthalpy of combustion of butanal, in kJ mol−1 ?
-6.2
+6.2
-2480
+2480
Consider the reaction pathways shown. According to Hess’s Law, the enthalpy change, in kJ mol−1 , for reaction X is
+111
-111
-677
+677
Consider the reaction pathway shown. According to Hess’s Law
b = a - c - d
b = a + c + d
b = d - c + a
b = d + c - a.
Which of the following is not a factor that affects the rate of a reaction?
Activation energy
Kinetic energies of reactant molecules
Concentration of reactants
Enthalpy change of reaction
Iron can be produced from iron(III) oxide. The atom economy for the production of iron is
69∙9%
62∙8%
58∙2%
32∙5%
100 cm3 of propane is mixed with 600 cm3 of oxygen and the mixture is ignited.
C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(ℓ)
At the end of the reaction, the total volume of gas would be
300 cm3
400 cm3
700 cm3
800 cm3
In which of the following reactions would the yield of product be increased by lowering the pressure?
H2(g) + I2(g) ⇌ 2HI(g
N2(g) + 3H2(g) ⇌ 2NH3(g)
N2O4(g) ⇌ 2NO2(g)
CO(g) + 2H2(g) ⇌ CH3OH(g)
