IB Chemistry SL
Topic1 Questions
1.
What amount of oxygen, O2, (in moles) contains 1.8×1022 molecules?
A.
0.0030
B.
0.030
C.
0.30
D.
3.0
(Total 1 mark)
2.
Which compound has the empirical formula with the greatest mass?
A.
C2H6
B.
C4H10
C.
C5H10
D.
C6H6
(Total 1 mark)
3.
__C2H2(g) + __O2(g) → __ CO2(g) + __ H2O(g)
When the equation above is balanced, what is the coefficient for oxygen?
A.
2
B.
3
C.
4
D.
5
(Total 1 mark)
4.
3.0 dm3 of sulfur dioxide is reacted with 2.0 dm3 of oxygen according to the equation below.
2SO2(g) + O2(g) → 2SO3(g)
What volume of sulfur trioxide (in dm3) is formed? (Assume the reaction goes to completion
and all gases are measured at the same temperature and pressure.)
A.
5.0
B.
4.0
C.
3.0
D.
2.0
(Total 1 mark)
5.
What will happen to the volume of a fixed mass of gas when its pressure and temperature
(in Kelvin) are both doubled?
A.
It will not change.
B.
It will increase.
C.
It will decrease.
D.
The change cannot be predicted.
(Total 1 mark)
6.
What amount (in moles) is present in 2.0 g of sodium hydroxide, NaOH?
A.
0.050
B.
0.10
C.
20
D.
80
(Total 1 mark)
7.
A hydrocarbon contains 90% by mass of carbon. What is its empirical formula?
A.
CH2
B.
C3H4
C.
C7H10
D.
C9H10
(Total 1 mark)
8.
Copper can react with nitric acid as follows.
3Cu +_HNO3 → _Cu(NO3)2 +_H2O + _NO
What is the coefficient for HNO3 when the equation is balanced?
A.
4
B.
6
C.
8
D.
10
(Total 1 mark)
IB Chemistry – SL
Topic 6 Questions
9.
10.
11.
Which statement is correct for a collision between reactant particles leading to a reaction?
A.
Colliding particles must have different energy.
B.
All reactant particles must have the same energy.
C.
Colliding particles must have a kinetic energy higher than the activation energy.
D.
Colliding particles must have the same velocity.
Which change of condition will decrease the rate of the reaction between excess zinc
granules and dilute hydrochloric acid?
A.
increasing the amount of zinc
B.
increasing the concentration of the acid
C.
pulverize the zinc granules into powder
D.
decreasing the temperature
The table shows the concentrations of reactants and products during this reaction.
2A + B → C + 2D
[A] / mol dm–3
[B] / mol dm–3
[C] / mol dm–3
[D] / mol dm–3
at the start
6
3
0
0
after 1 min
4
2
1
2
The rate of reaction can be measured by reference to any reactant or product. Which rates are
correct for this reaction?
I.
II.
III.
12.
rate = –2 mol dm–3 min–1 for A
rate = –1 mol dm–3 min–1 for B
rate = –1 mol dm–3 min–1 for C
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
In general, the rate of a reaction can be increased by all of the following except
13.
14.
15.
A.
increasing the temperature.
B.
increasing the activation energy.
C.
increasing the concentration of reactants.
D.
increasing the surface area of the reactants.
At 25°C, 100 cm3 of 1.0 mol dm–3 hydrochloric acid is added to 3.5 g of magnesium
carbonate. If the sample of magnesium carbonate is kept constant, which conditions will not
increase the initial rate of reaction?
Volume of HCl / cm3
Concentration of HCl / mol dm–3
Temperature / °C
A.
200
1.0
25
B.
100
2.0
25
C.
100
1.0
35
D.
200
2.0
25
At 25°C, 100 cm3 of 1.0 mol dm–3 hydrochloric acid is added to 3.5 g of magnesium
carbonate. If the sample of magnesium carbonate is kept constant, which conditions will not
increase the initial rate of reaction?
Volume of HCl / cm3
Concentration of HCl / mol dm–3
Temperature / °C
A.
200
1.0
25
B.
100
2.0
25
C.
100
1.0
35
D.
200
2.0
25
Which statement is correct with regard to the catalysed and uncatalysed pathways for a given
reaction?
A.
The enthalpy change of the catalysed reaction is less than the enthalpy change for the
uncatalysed reaction.
B.
The enthalpy change of the catalysed reaction is greater than the enthalpy change for
the uncatalysed reaction.
C.
The enthalpy change of the catalysed reaction is equal to the enthalpy change for the
uncatalysed reaction.
D.
The activation energy of the catalysed reaction is greater than the activation energy for
the uncatalysed reaction.
IB Chemistry – HL
Topic 6 Questions
1.
The reaction between NO2 and F2 gives the following rate data at a certain temperature.
What is the order of reaction with respect to NO2 and F2?
[NO2]/mol dm–3
[F2]/mol dm–3
Rate /mol dm–3 min–
1
2.
3.
0.1
0.2
0.1
0.2
0.2
0.4
0.1
0.4
0.2
NO2 order
F2 order
A.
first
first
B.
first
second
C.
second
first
D.
second
second
Which step in a multi-step reaction is the rate determining step?
A.
The first step
B.
The last step
C.
The step with the lowest activation energy
D.
The step with the highest activation energy
The rate expression for a reaction is shown below.
rate = k[A]2[B]2
Which statements are correct for this reaction?
4.
I.
The reaction is second order with respect to both A and B.
II.
The overall order of the reaction is 4.
III.
Doubling the concentration of A would have the same effect on the rate of
reaction as doubling the concentration of B.
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
Values of a rate constant, k, and absolute temperature, T, can be used to determine the
activation energy of a reaction by a graphical method. Which graph produces a straight line?
5.
A.
k versus T
B.
k versus
C.
ln k versus T
D.
ln k versus
The rate expression for a particular reaction is
Rate = k[P][Q]
Which of the units below is a possible unit for k?
6.
A.
mol–2 dm6 min–1
B.
mol–1 dm3 min–1
C.
mol dm3 min–1
D.
mol–2 dm–6 min–1
The reaction 2X(g) + Y(g) → 3Z(g) has the rate expression
rate = k [X]2[Y]0
The concentration of X is increased by a factor of three and the concentration of Y is
increased by a factor of two. By what factor will the reaction rate increase?
7.
A.
6
B.
9
C.
12
D.
18
A reaction occurs in four steps. The steps and their rates are shown in the table
Step
Rate
1
0.01 mol dm–3 s–1
2
0.10 mol dm–3 s–1
3
0.01 mol dm–3 min–1
4
0.10 mol dm–3 min–1
Which is the rate-determining step?
8.
A.
Step 1
B.
Step 2
C.
Step 3
D.
Step 4
The rate expression for a reaction is
rate = k[CH3Br][OH–]
Which is a possible unit for k?
9.
10.
A.
mol2 dm–6 min–1
B.
mol dm–3 min–1
C.
mol–1 dm3 min–1
D.
mol–2 dm6 min–1
What happens to the rate constant (k) and activation energy (Ea) of a reaction when the
temperature is increased?
A.
k increases and Ea is unaffected.
B.
k decreases and Ea is unaffected.
C.
Ea increases and k is unaffected.
D.
Ea decreases and k is unaffected.
The mechanism of a reaction is
XY2 + XY2 → X2Y4
X2Y4 → X2 + 2Y2
X2 + Y2 → 2XY
What is the overall equation for the reaction?
11.
A.
X2Y4 → 2XY2
B.
2XY2 → X2 + 2Y2
C.
2XY2 → 2XY + Y2
D.
X2Y4 → 2XY + Y2
Consider the reaction
2I−(aq) + H2O2(aq) + 2H+(aq) → I2(aq) + 2H2O(l)
In the presence of S2O32–(aq) and starch solution, the time taken for a blue colour to form
was observed at various reactant concentrations.
Experiment
[I–] / mol dm–3
[H2O2] / mol dm–3
[H+] / mol dm–3
Time / s
1
0.10
0.12
0.01
25
2
0.05
0.12
0.01
50
3
0.10
0.06
0.01
100
What is the correct order with respect to I– and H2O2?
I–
H2O2
1
2
C.
2
1
D.
2
4
A.
B.
16.
Nitrogen(II) oxide reacts with hydrogen as shown by the following equation.
2NO(g) + 2H2(g) → N2(g) + 2H2O(g)
The table below shows how the rate of reaction varies as the reactant concentrations vary.
Experiment
1
2
3
4
(a)
Initial [NO] /
mol dm–3
0.100
0.100
0.200
0.300
Initial [H2] / mol
dm–3
0.100
0.200
0.100
0.100
Initial rate /
mol N2 dm–3 s–1
2.53×10–6
5.05×10–6
10.10×10–6
22.80×10–6
Determine the order of reaction with respect to NO and with respect to H2.
Explain how you determined the order for NO.
NO ..............................................................................................................................
.....................................................................................................................................
H2 ................................................................................................................................
.....................................................................................................................................
(3)
(b)
Write the rate expression for the reaction.
.....................................................................................................................................
(1)
(c)
Calculate the value for the rate constant, including its units.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(d)
A suggested mechanism for this reaction is as follows.
H2 + NO
X fast step
X + NO → Y + H2O slow step
Y + H2 → N2 + H2O fast step
State and explain whether this mechanism agrees with the experimental rate
expression in (b).
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(4)
(e)
Explain why a single step mechanism is unlikely for a reaction of this kind.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(f)
Deduce how the initial rate of formation of H2O(g) compares with that of N2(g) in
experiment 1. Explain your answer.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(Total 14 marks)
17.
The oxidation of nitrogen monoxide takes place as follows:
2NO(g) + O2(g) → 2NO2(g)
The following experimental data was obtained at 101.3 kPa and 298 K.
(a)
Experiment
Initial [NO] / mol dm–3
Initial [O2] / mol dm–3
Initial rate / mol dm–3 s–1
1
3.50×10–2
1.75×10–2
3.75×10–3
2
3.50×10–2
3.50×10–2
7.50×10–3
3
7.00×10–2
7.00×10–2
6.00×10–2
Deduce the order of reaction with respect to O2.
...................................................................................................................................
...................................................................................................................................
(1)
(b)
Deduce the order of reaction with respect to NO.
...................................................................................................................................
...................................................................................................................................
(1)
(c)
State the rate expression for the reaction.
...................................................................................................................................
(1)
(d)
Calculate the value of the rate constant and state the units.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
(2)
(e)
Suggest a possible mechanism that is consistent with the rate expression. Indicate
which of the steps is the rate-determining step.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
(3)
(Total 8 marks)
18.
An equation for the decomposition of substance A is
2A → 2B + C
A graph showing the change in concentration of A against time as the reaction proceeds at a
particular temperature is shown below.
(a)
Define the term half-life of reaction.
...................................................................................................................................
...................................................................................................................................
(1)
(b)
Use the graph to measure values of half-life of reaction, starting from
time = zero ................................................................................................................
time = 1000 s ............................................................................................................
(2)
(c)
Deduce the order of the reaction with respect to A, giving a reason for your choice,
and write the rate expression for the reaction.
...................................................................................................................................
...................................................................................................................................
(3)
(d)
For a different reaction, between compounds D and E, the rate expression is
rate = k[D]2[E]
Calculate the value of k, including units, for the reaction when the concentrations of
both D and E are 1.35×10–2 mol dm–3 and the reaction rate is 3.75×10–5 mol dm–3
min–1.
(3)
(Total 9 marks)
Answers:
3.
D
1.
4.
C
5.
A
2.
B
B
6.
A
Topic 6 Answers
7.
B
1.
C
8.
9.
C
2.
D
10.
D
3.
4.
D
D
11.
A
5.
12.
B
6.
B
13.
A
7.
C
14.
A
8.
C
15.
C
9.
A
10.
C
11.
A
C
IB Chemistry – HL
16.
(a)
(order with respect to) NO = 2;
(order with respect to) H2 = 1;
rate increases×4 when [NO] doubles/OWTTE; 3
B
(b) rate = k[NO]2[H2];
ECF from (a).
(c)
1
(2.53×10–6 mol dm–3 s–1 = k (0.100 mol dm–3)2(0.100 mol dm–3))
k = 2.53×10–3;
1
mol –2 dm6 s–1;
ECF from (b).
1
(d)
agrees/yes;
slow step depends on X and NO;
X depends on H2 and NO;
(so) NO is involved twice and H2 once;
Overall equation matches the stoichiometric equation;
Award [1] each for any three of the four above.
OWTTE
ECF for “no”, depending on answer for (b).
Or
agrees/yes;
and
= constant;
rate of slow step = k [X][NO]
= k [H2][NO]2;
4
ECF for “no”, depending on answer for (b).
(e)
(f)
reaction involves four molecules;
statistically/geometrically unlikely;
2
the rate of formation of H2O(g) = 2×rate for N2(g);
because 2 moles H2O formed with 1 mole N2/OWTTE;
2
[14]
17.
(a)
first order (with respect to O2);
1
(b)
second order (with respect to NO);
1
(c) rate = k[NO]2[O2];
Allow ECF from parts (a) and (b).
1
(d)
dm6 mol–2 s–1;
Award [1] mark for the answer and [1] mark for units.
Allow ECF from part (c).
(e)
NO + NO
N2O2;
N2O2 + O2 → 2NO2;
second step is rate determining step;
2
Allow ECF from part (c).
OR
NO + O2
NO3;
NO3 + NO → 2NO2;
second step is rate determining step;
Allow ECF from part (c).
3
[8]
18. (a) time for reactant concentration to halve/OWTTE;
Accept “time for mass to halve”.
1000 s;
1000 s;
Accept 900-1100 s.
1
(b)
first order;
constant half-life;
rate = k[A];
Allow ECF for rate expression from stated order.
2
(c)
3
(d)
= 15.2;
Accept answer in range 15.2 to 15.3.
mol−2 dm6 min−1;
3
[9]