Kinetics practice 2

Which statements are correct?

I. The activation energy of a reaction is not affected by temperature.

II. A catalyst reduces the enthalpy change of a reaction.

III. Catalysts provide alternative reaction pathways.

• I and II only

• I and III only

• II and III only

• I, II and III

Which factors can affect the rate of reaction?

I. Particle size of solid reactant

II. Concentration of reacting solution

III. Pressure of reacting gas

• I and II only

• I and III only

• II and III only

• I, II and III

Tags

NGSS.HS-PS1-5

The diagram shows the energy profile for a catalysed and uncatalysed reaction.

Which represents the enthalpy change, ΔH, and the activation energy, Ea, for the catalysed reaction?

• ΔH is z, E_a (catalysed reaction) is x + z

• ΔH is z, E_a (catalysed reaction) is z + y

• ΔH is -z, E_a (catalysed reaction) is x

• ΔH is z + x, E_a (catalysed reaction) is x

Which variable is best to use when determining the rate of decomposition of hydrogen peroxide?

2H₂O₂(l) → 2H₂O(l)+O₂(g)

• Volume of solution

• Volume of gas

• pH of solution

• Conductivity of solution

Tags

NGSS.HS-PS1-5

Which is a correct unit for expressing the rate of a reaction?

• mol L^-1 s^-1

• mol L^-1 s

• mol s

• mol-1 L s^-1

1.00 mol L⁻¹ solution of hydrochloric acid is added to 2.00 g of small pieces of calcium carbonate at 20°C. The volume of carbon dioxide produced against time is plotted to give curve P.

Which change will produce curve Q, given that calcium carbonate is always the limiting reagent?

• Increasing the volume of the hydrochloric acid to 200 mL

• Increasing the mass of calcium carbonate to 4.00 g

• Increasing the concentration of the hydrochloric acid to 2.00 mol L⁻¹

• Replacing the 2.00 g of small pieces of calcium carbonate with 2.00 g of larger pieces of calcium carbonate

Which quantity can be changed by the use of a catalyst?

• I and II only

• I and III only

• II and III only

• I, II and III

The diagram represents the Maxwell‒Boltzmann energy distribution curve of the reactants for a chemical reaction with different activation energies, E_a1 and E_a2.

What is the reason why the rate of the reaction with activation energy E_a2 is greater?

• More frequent collisions between the particles occur.

• More energetic collisions between the particles occur.

• A catalyst has been added.

• The temperature is higher.

Which change increases the rate of a chemical reaction?

• Increasing the size of solid reactant particles

• Decreasing the concentration of aqueous reactants

• Increasing the surface area of a solid reactant

• Decreasing the pressure of gaseous reactants

Which is not affected by an increase in temperature?

• Rate of reaction

• Collision frequency

• Collision geometry

• % of molecules with E ≥ E_a