KINETICS - 2

Answer explanation

A is incorrect because Y has been multiplied by 2 instead of raised to the power of its coefficient

C is incorrect because the expression has been inverted and because Y has been multiplied by 2 instead of raised to the power of its coefficient

D is incorrect because the expression has been inverted

• Type of equilibrium= heterogeneous

  Effect of increasing

  temperature on Kc=

  decreases

• Type of equilibrium= homogeneous

  Effect of increasing

  temperature on Kc=

  decreases

• Type of equilibrium= heterogeneous

  Effect of increasing

  temperature on Kc=

  Increases

• Type of equilibrium= homogeneous

  Effect of increasing

  temperature on Kc=

  Increases

Answer explanation

A is incorrect because the system is homogenous at 360⁰C

C is incorrect because the system is homogenous at 360⁰C and Kc decreases

D is incorrect because Kc decreases

• atm^–1

• atm

• atm^–2

• atm²

Answer explanation

A is incorrect because coefficients have not been taken into account

B is incorrect because coefficients have not been taken into account and the expression has been inverted

D is incorrect because these are the units for the inverted expression

• rate = k[H₂O₂]²[I^–]

• rate = k[H₂O₂][I^–]

• rate = k[H₂O₂]²[I^–][IO^–]

• rate = k[H₂O₂][IO^–]

Answer explanation

B is incorrect because the concentration of hydrogen peroxide should be squared

C is incorrect because this includes an intermediate

D is incorrect because the concentration of hydrogen peroxide should be squared and includes an intermediate

• Equation 1

  rate = k[NO]²[O₂]

  Equation 2

  rate = k[NO]²[O₂]

• Equation 1

  rate = k[NO]²[O₂]

  Equation 2

  rate = k[NO][O₂]^1⁄2

• Equation 1

  rate = k[NO₂]²

  Equation 2

  rate = k[NO₂]²

• Equation 1

  rate = k[NO₂]²

  Equation 2

  rate = k[NO₂]

Answer explanation

2. B  is incorrect because the rate equation is not determined by the stoichiometric equation

3. C  is incorrect because the rate cannot depend only on the concentration of products

4. D  is incorrect because the rate cannot depend only on the concentration of products

• 1. colorimetry and titration

• 1. colorimetry and volume change

• 1. mass change and volume change

• 1. mass change and titration

Answer explanation

2. A is incorrect because titration cannot be used for continuous monitoring of a reaction C is incorrect because the mass of the system does not change

   D is incorrect because the mass of the system does not change and titration cannot be used for continuous monitoring of a reaction

2. The half‐life of a first order chemical reaction is

• 1. half the time taken for the reaction to be complete

• 1. the time taken for the value of the rate constant to halve

• 1. the time taken for the concentration of a reactant to halve

• 1. the time taken for the concentration of a product to double

Answer explanation

1. A  is incorrect because the reaction is slower and slower as it progresses

2. B  is incorrect because the rate constant does not change at a given temperature

D is incorrect because time taken for the concentration of a product to double will vary

2. Two chemicals, E and F, react to form products G and H.
   E + 2F → G + H

3. The mechanism for the reaction occurs in two steps via the formation of an intermediate J.

4. E+F→J slow

5. J+F→G+H fast

6. What is the rate equation for the reaction?

• 1. rate = k[E][F]

• 1. rate = k[E][F]²

• 1. rate = k[F][J]

• 1. rate = k[E][F]²[J]

Answer explanation

B is incorrect because the rate depends on concentrations of the reacting species in the slow step and the stoichiometry of this step

C is incorrect because the rate equation cannot include intermediate concentrations

D is incorrect because the rate depends on concentrations of the reacting species in the slow step and the stoichiometry of this step and the rate equation cannot include intermediate concentrations

Which continuous monitoring method could be used to obtain rate data for the reaction shown?

C₄H₉Cl_(l) + H^₂O_(l) → C₄H₉OH_(aq) + H⁺_(aq) + Cl⁻_(aq)

• electrical conductivity

• colorimetry
  

• colorimetry
  

• titration with alkali

Answer explanation

B is not correct because none of the reactants or products is coloured
C is not correct because there is no change in mass
D is not correct because titration is not a continuous monitoring method

Nitrogen monoxide is reduced by hydrogen.
2NO_(g) + 2H_2(g) → N_2(g) + 2H₂O_(g)

The rate equation for the reaction is

rate = k [NO]² [H₂]

The concentrations of both reactants are tripled.

By what factor does the rate of reaction increase?

• 3

• 9

• 18

• 27

Answer explanation

A is not correct because the reaction is not overall first order
B is not correct because the reaction is not overall second order
C is not correct because the reaction is second order with respect to NO and first order with respect to H2