Rate of Reaction

The rate of reaction between X and Y is third order overall. Which of the following rate equations must be INCORRECT?

• Rate = k[X] [Y]³

• Rate = k[X] [Y]²

• Rate = k[X]² [Y]

• Rate = k[X]⁰ [Y]³

The rate of reaction between P and Q is determined experimentally and the data is presented in the table.

Experiment

From the data, the rate equation is

• Rate = k[P]²

• Rate = k[P][Q]

• Rate = k[P][Q]²

• Rate = k[Q]²

Which one of the following correctly represents the unit of the rate constant k for a first order reaction?

• s^-1

• mol dm^-3 s^-1

• mol dm^-3 s

• mol^-1 dm³ s

Which of the following graphs would confirm that the decomposition of hydrogen peroxide was first order with respect to the concentration of hydrogen peroxide?

• A

• B

• C

• D

If the reaction

P + Q → R + S

Is described as zero order with respect to P, it means that

• P is a catalyst in this reaction

• No P molecules possess sufficient energy to react

• The rate of the reaction is independent of the concentration of P

• The rate of the reaction is proportional to the concentration of Q

A radioactive isotope decays from an initial count of 160cpm to 20cpm in 27 days. What is its half-life?

• 3 days

• 6 days

• 9 days

• 12 days

Under which conditions will the rate of a chemical reaction always decrease

• The concentration of the reactants increases, and the temperature decreases.

• The concentration of the reactants decreases, and the temperature decreases.

• The concentration of the reactants decreases, and the temperature increases.

• The concentration of the reactants increases, and the temperature increases.

Which one of the following is a correct statement about the effect of a catalyst?

• It increases the equilibrium constant for the forward reaction

• It increases the rate constant for the forward reaction but not that of the back reaction

• It increases the speed of the reactant particles and therefore the rate of molecular collision

• It provided an alternative route for a reaction.

The graph below shows the Maxwell- Boltzmann distribution of kinetic energies in a gas.

Which statements are correct for the Maxwell- Boltzmann distribution?

Increase in temperature

I. causes the maximum of the curve to move to the right

II. causes the maximum of the curve to move to the left.

III. increases the number of molecules present in the gas.

IV. increases the number of molecules with energy greater than the activation energy

• I and III

• I and IV

• II and III

• II and IV

The Boltzmann distribution of molecular energies at two temperatures T₁ and T₂ is shown below

Which area represents the additional number of molecules having the activation energy, E_a at the higher temperature T₂?

• X

• Y

• X + Y

• X –Y