DP Chemistry Questionbank

Which experimental methods could be used to observe the progress of the following reaction?

Cr₂O₇^2-(aq) + 6I^-(aq) + 14H⁺(aq) → 2Cr³⁺(aq) + 3I₂(aq) + 7H₂O(l) 

I. Change in colour 
II. Change in mass 
III. Change in electrical conductivity 

A.  I and II only 

B.  I and III only 

C.  II and III only 

D.  I, II and III

A student decided to carry out another experiment using 0.075 mol dm^-3 solution of sodium thiosulfate under the same conditions. Determine the time taken for the mark to be no longer visible.

Draw the best fit line of $\frac{1}{\mathrm{t}}$ against concentration of sodium thiosulfate on the axes provided.

An additional experiment was carried out at a higher temperature, T₂.

(i) On the same axes, sketch Maxwell–Boltzmann energy distribution curves at the two temperatures T₁ and T₂, where T₂ > T₁.

(ii) Explain why a higher temperature causes the rate of reaction to increase.

Suggest how the change of iodine concentration could be followed.

The student then carried out the experiment at other acid concentrations with all other conditions remaining unchanged.

State and explain the relationship between the rate of reaction and the concentration of acid.

Copper catalyses the reaction between zinc and dilute sulfuric acid.

Zn(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂(g)

Why does copper affect the reaction?

A.     Decreases the activation energy

B.     Increases the activation energy

C.     Increases the enthalpy change

D.     Decreases the enthalpy change

100 cm³ of 10% hydrogen peroxide solution decomposes at 298 K to form water and oxygen.

H₂O₂(aq) → H₂O(l) + $\frac{1}{2}$O₂(g)

The dotted line graph represents the volume of oxygen produced.

Which graph represents the decomposition of an equal volume of a 20% solution under the same conditions?

A student produced these results with [H⁺] = 0.15 mol$$dm⁻³. Propanone and acid were in excess and iodine was the limiting reagent.

Determine the relative rate of reaction when [H⁺] = 0.15 mol$$dm⁻³.

The student then carried out the experiment at other acid concentrations with all other conditions remaining unchanged.

Determine the relationship between the rate of reaction and the concentration of acid and the order of reaction with respect to hydrogen ions.

Which methods can be used to monitor the progress of this reaction?

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

Outline why the rate of the reaction decreases with time.

Sketch, on the same graph, the expected results if the experiment were repeated using powdered magnesium, keeping its mass and all other variables unchanged.

Which change does not increase the initial rate of reaction when CaCO₃(s) is added to excess HCl(aq)?

A.     Decrease in the size of the CaCO₃(s) particles

B.     Increase in the temperature of the reaction mixture

C.     Increase in the concentration of HCl(aq), keeping the same volume

D.     Increase in the volume of HCl(aq), keeping the same concentration

Which apparatus can be used to monitor the rate of this reaction?

${\mathrm{CH}}_3{\mathrm{COCH}}_3 \left(\mathrm{aq}\right)+{\mathrm{I}}_2 \left(\mathrm{aq}\right)\to {\mathrm{CH}}_3{\mathrm{COCH}}_2\mathrm{I} \left(\mathrm{aq}\right)+{\mathrm{H}}^{+} \left(\mathrm{aq}\right)+{\mathrm{I}}^{-} \left(\mathrm{aq}\right)$

1. A pH meter
2. A gas syringe
3. A colorimeter
   

A.  I and II only

B.  I and III only

C.  II and III only

D.  I, II and III

Which arrow shows the activation energy of the uncatalysed forward reaction for this equilibrium?

$2{\mathrm{SO}}_2 \left(\mathrm{g}\right)+{\mathrm{O}}_2 \left(\mathrm{g}\right)\rightleftharpoons 2{\mathrm{SO}}_3 \left(\mathrm{g}\right)$     $∆H=-196 \mathrm{kJ} {\mathrm{mol}}^{-1}$

Which change does not increase the rate of this reaction?

${\mathrm{CuCO}}_3 \left(\mathrm{s}\right)+{\mathrm{H}}_2{\mathrm{SO}}_4 \left(\mathrm{aq}\right)\to {\mathrm{CuSO}}_4 \left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right)+{\mathrm{CO}}_2 \left(\mathrm{g}\right)$

A.  Increasing the particle size of the ${\mathrm{CuCO}}_3$

B.  Increasing the temperature

C.  Increasing the concentration of ${\mathrm{H}}_2{\mathrm{SO}}_4 \left(\mathrm{aq}\right)$

D.  Stirring the reaction mixture

Outline how a catalyst increases the rate of reaction.

Explain why an increase in temperature increases the rate of reaction.

Outline how a catalyst increases the rate of reaction.

Nitrogen monoxide reacts with oxygen gas to form nitrogen dioxide.

The following experimental data was obtained.

Deduce the partial order of reaction with respect to nitrogen monoxide and oxygen.

Excess magnesium powder was added to a beaker containing hydrochloric acid, HCl (aq).

The mass of the beaker and its contents was recorded and plotted against time (line I).

Which change could give line II?

A. Doubling the mass of powdered Mg

B. Using the same mass of Mg ribbon

C. Increasing the temperature

D. Using the same volume of more concentrated HCl

Suggest two variables, besides the time of reaction, which the student should have controlled in the experiment to ensure a fair comparison of the antacids.

Which change causes the greatest increase in the initial rate of reaction between nitric acid and magnesium?

2HNO₃(aq) + Mg (s) → Mg(NO₃)₂ (aq) + H₂(g)

The diagram shows the Maxwell-Boltzmann curve for the uncatalyzed reaction.

Draw a distribution curve at a lower temperature (T₂) and show on the diagram how the addition of a catalyst enables the reaction to take place more rapidly than at T₁.

Deduce the relationship between the concentration of N₂O₅ and the rate of reaction.

The diagram shows the Maxwell-Boltzmann curve for the uncatalyzed reaction.

Draw a distribution curve at a lower temperature (T₂) and show on the diagram how the addition of a catalyst enables the reaction to take place more rapidly than at T₁.

Outline two ways in which the progress of the reaction can be monitored. No practical details are required.

Suggest why point D is so far out of line assuming human error is not the cause.

Suggest the relationship that points A, B and C show between the concentration of the acid and the rate of reaction.

Which change increases the rate of formation of hydrogen when zinc reacts with excess hydrochloric acid, assuming all other conditions remain the same?

Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)

A.     Adding water to the hydrochloric acid

B.     Decreasing the temperature

C.     Increasing the volume of hydrochloric acid

D.     Decreasing the size of the zinc particles while keeping the total mass of zinc the same

Outline two ways in which the progress of the reaction can be monitored. No practical details are required.

Suggest why point D is so far out of line assuming human error is not the cause.

Suggest the relationship that points A, B and C show between the concentration of the acid and the rate of reaction.

Suggest why there is a small increase in the surface pressure as the area is reduced to about 240 cm², but a much faster increase when it is further reduced.

Neither method actually gives the initial rate. Outline a method that would allow the initial rate to be determined.

Deduce, giving a reason, which of the two methods would be least affected by the chips not having exactly the same mass when used with the different concentrations of acid.

State a factor, that has a significant effect on reaction rate, which could vary between marble chips of exactly the same mass.

The potential energy profile for the reversible reaction, X + Y ƒ$\rightleftharpoons$ Z is shown.

Which arrow represents the activation energy for the reverse reaction, Z → X + Y, with a catalyst?

Sketch a curve on the graph to show the volume of gas produced over time if the same mass of crushed calcium carbonate is used instead of lumps. All other conditions remain constant.

Sketch a Maxwell–Boltzmann distribution curve for a chemical reaction showing the activation energies with and without a catalyst.

Explain why aspirin is not stored in a hot, humid location.

Which instrument would best monitor the rate of this reaction?

2KI (aq) + Cl₂(aq) → 2KCl (aq) + I₂(aq)

A.  Balance

B.  Colorimeter

C.  Volumetric flask

D.  Gas syringe

Sketch labelled Maxwell–Boltzmann energy distribution curves at the original temperature (T₁) and the new lower temperature (T₂).

A student was investigating rates of reaction. In which of the following cases would a colorimeter show a change in absorbance?

A.  KBr (aq) + Cl₂(aq)

B.  Cu (s) + Na₂SO₄(aq)

C.  HCl (aq) + NaOH (aq)

D.  (CH₃)₃COH (aq) + K₂Cr₂O₇(aq)

Sketch a graph of the concentration of iron(II) sulfate, FeSO₄, against time as the reaction proceeds.

Sketch a graph of the concentration of iron(II) sulfate, FeSO₄, against time as the reaction proceeds.

Samples of sodium carbonate powder were reacted with separate samples of excess hydrochloric acid.

Na₂CO₃ (s) + 2HCl (aq) → CO₂ (g) + 2NaCl (aq) + H₂O (l)

Reaction I: 1.0 g Na₂CO₃ (s) added to 0.50 mol dm⁻³ HCl (aq)

Reaction II: 1.0 g Na₂CO₃ (s) added to 2.0 mol dm⁻³ HCl (aq)

What is the same for reactions I and II?

A.   Initial rate of reaction

B.   Total mass of CO₂ produced

C.   Total reaction time

D.   Average rate of production of CO₂

Outline how the initial rate of reaction can be determined from the graph in part (c)(i).

Outline how the initial rate of reaction can be determined from the graph in part (c)(i).

Outline, giving a reason, the effect of a catalyst on a reaction.

Outline, giving a reason, the effect of a catalyst on a reaction.

On the axes, sketch Maxwell–Boltzmann energy distribution curves for the reacting species at two temperatures T₁ and T₂, where T₂ > T₁.

Additional experiments were carried out at an elevated temperature. On the axes below, sketch Maxwell–Boltzmann energy distribution curves at two temperatures T₁ and T₂, where T₂ > T₁.

Apart from a greater frequency of collisions, explain, by annotating your graphs in (b)(iii), why an increased temperature causes the rate of reaction to increase.

The graph below shows the Maxwell–Boltzmann distribution of molecular energies at a particular temperature.

The rate at which dinitrogen monoxide decomposes is significantly increased by a metal oxide catalyst.

Annotate and use the graph to outline why a catalyst has this effect.

Outline, in terms of collision theory, how a decrease in pressure would affect the rate of reaction.

The experiment is repeated using the same amount of dinitrogen monoxide in the same apparatus, but at a lower temperature.

Sketch, on the axes in question 2, the graph that you would expect.

Outline, with a reason, another property that could be monitored to measure the rate of this reaction.

Examine, giving a reason, whether the rate of lead dissolving increases with acidity at 18 °C.

Determine from the graph the rate of reaction at 20 s, in cm³ s⁻¹, showing your working.

Identify the experiment with the highest rate of lead dissolving.

Which properties can be monitored to determine the rate of the reaction?

Fe (s) + CuSO₄ (aq) → Cu (s) + FeSO₄ (aq)

    I. change in volume
    II. change in temperature
    III. change in colour

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

The dotted line represents the formation of oxygen, O₂ (g), from the uncatalysed complete decomposition of hydrogen peroxide, H₂O₂ (aq).

Which curve represents a catalysed reaction under the same conditions?

Several reactions of calcium carbonate with dilute hydrochloric acid are carried out at the same temperature.

CaCO₃ (s) + 2HCl (aq) → CaCl₂ (aq) + H₂O (l) + CO₂ (g)

Which reaction has the greatest rate?

Apart from a greater frequency of collisions, explain, by annotating your graphs in (b)(ii), why an increased temperature causes the rate of reaction to increase.

Additional experiments were carried out at an elevated temperature. On the axes below, sketch Maxwell–Boltzmann energy distribution curves at two temperatures T₁ and T₂, where T₂ > T₁.

Outline, in terms of collision theory, how a decrease in pressure would affect the rate of reaction.

The graph below shows the Maxwell–Boltzmann distribution of molecular energies at a particular temperature.

The rate at which dinitrogen monoxide decomposes is significantly increased by a metal oxide catalyst.

Annotate and use the graph to outline why a catalyst has this effect.

The experiment is repeated using the same amount of dinitrogen monoxide in the same apparatus, but at a lower temperature.

Sketch, on the axes in question 2, the graph that you would expect.

Outline, with a reason, another property that could be monitored to measure the rate of this reaction.

Examine, giving a reason, whether the rate of lead dissolving increases with acidity at 18 °C.

Determine from the graph the rate of reaction at 20 s, in cm³ s⁻¹, showing your working.

Identify the experiment with the highest rate of lead dissolving.

Which properties can be monitored to determine the rate of the reaction?

Fe (s) + CuSO₄ (aq) → Cu (s) + FeSO₄ (aq)

    I. change in volume
    II. change in temperature
    III. change in colour

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

The dotted line represents the formation of oxygen, O₂(g), from the uncatalysed complete decomposition of hydrogen peroxide, H₂O₂ (aq).

Which curve represents a catalysed reaction under the same conditions?

Several reactions of calcium carbonate with dilute hydrochloric acid are carried out at the same temperature.

CaCO₃ (s) + 2HCl (aq) → CaCl₂ (aq) + H₂O (l) + CO₂ (g)

Which reaction has the greatest rate?

Explain how the catalyst increases the rate of the reaction.

Explain why the rate of reaction of limestone with nitric acid decreases and reaches zero over the period of five days.

Determine the initial rate of reaction of limestone with nitric acid from the graph.

Show your working on the graph and include the units of the initial rate.

Explain how the catalyst increases the rate of the reaction.