Target: 10 Questions in 10 minutes

An IB Chemistry data booklet is helpful
1. In the reaction between magnesium and hydrochloric acid,

Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)

which set of conditions gives the slowest rate of reaction?

  
  • A.   0.1 g of magnesium ribbon and 30 cm3 of 0.5 mol dm-3 hydrochloric acid at room temperature
  • B.   0.1 g of magnesium powder and 30 cm3 of 0.5 mol dm-3 hydrochloric acid at room temperature
  • C.   0.1 g of magnesium ribbon and 30 cm3 of 0.5 mol dm-3 hydrochloric acid at 40 oC
  • D.   0.1 g of magnesium ribbon and 15 cm3 of 1.0 mol dm-3 hydrochloric acid at room temperature
2. Which of the following factors does not affect the rate of a reaction?
  • A.   the enthalpy change of the reaction
  • B.   the concentration of the reactants
  • C.   the orientation of the reactants
  • D.   the temperature of the reaction mixture
3. The rate of reactions can sometimes be followed by changes in colour. A visible light spectrophotometer can be used to determine the rates of all the following reactions except:
  • A.   Zn(s) + CuSO4(aq)  → ZnSO4(aq) + Cu(s)
  • B.   K2S2O8(aq) + 2KI(aq)  → 2K2SO4(aq) + I2(aq)
  • C.   CaCO3(s) + 2HCl(aq)  → CaCl2(aq) + H2O(l) + CO2(g)
  • D.   5KBr(aq) + KBrO3(aq) + 3H2SO4(aq)  → 3Br2(aq) + 3H2O(l) + 3K2SO4(aq)
4. Increasing temperature increases the rate of a reaction. What is the main reason for this according to the Collision Theory?
  • A.   The frequency of particle collisions increases.
  • B.   The proportion of particles with energy greater than activation energy increases.
  • C.   The activation energy decreases.
  • D.   The average kinetic energy of the particles increases.
5. The equation below shows the oxidation of ethanol by acidified potassium dichromate(VI):

3CH3CH2OH(l) + 8H+ (aq) + Cr2O72-(aq) → 2Cr3+(aq) + 3CH3CHO(aq) + 7H2O(l)

Which of the following three pieces of apparatus can be used to monitor the rate of reaction?

I. a balance
II. a colorimeter
III. a pH meter
 
  • A.   I and II only
  • B.   I and III only
  • C.   II and III only
  • D.   I, II and III

6-8: The reaction between zinc and dilute sulphuric acid produces hydrogen, and the volume of the gas can be plotted against time to show the rate of the reaction. The solid line in the graph below shows the result for the reaction between 10 g of zinc granules and 30 cm3 of 0.5 mol dm-3 sulphuric acid.

rates of reaction graph with 4 options

Which of the following dotted lines (A-D) best represents the results for:

 
6. 10 g of zinc powder and 30 cm3 of 0.5 mol dm-3 sulphuric acid 
7. 10 g of zinc granules and 30 cm3 of 0.5 mol dm-3 sulphuric acid, with a copper turning catalyst
8. 10 g of zinc granules and 60 cm3 of 0.25 mol dm-3 sulphuric acid

 

9. In the decomposition reaction of 50 cm3 of 0.16 mol dm-3 hydrogen peroxide, catalysed by manganese(IV) oxide MnO2,

2H2O2(aq)  → 2H2O(l) + O2(g)

the graph below shows the concentration of H2O2 plotted against time.

rates of reaction graph Q9

What is the average rate of the reaction in the first 100 seconds, as shown by the graph?

  
  • A.   0.0016 cm3 s-1
  • B.   0.0016 mol dm-3 s-1
  • C.   0.0008 cm3 s-1
  • D.   0.0008 mol dm-3 s-1
10. A student follows the rate of a reaction between potassium permanganate and oxalic acid, by observing the time taken for the colour of potassium permanganate to disappear. The equation for this reaction is:

2KMnO4(aq) + 3H2SO4(aq) + 5C2H2O4(aq) → K2SO4(aq) + 2MnSO4(aq) + 8H2O(l) + 10CO2(g)

The following reaction mixture was set up, with potassium permanganate as the limiting reactant. It took 50 seconds for the colour of the reaction mixture to change from purple to colourless.

Reactant Concentration of stock solution
(mol dm-3)		 Volume of stock solution
(cm3)
KMnO4 0.025 10
H2SO4 0.5 10
C2H2O4 1 10
 

What is the rate of loss of potassium permanganate?

  • A.   5.00 x 10-6 mol dm-3 s-1
  • B.   1.67 x 10-4 mol dm-3 s-1
  • C.   5.00 x 10-4 mol dm-3 s-1
  • D.   5.00 x 10-3 mol dm-3 s-1