Question

If the rate law for a reaction is Rate = k [ClO_3^-][I^-][H^+]^2 what are the units of k when the unit of time is seconds and the unit of concentration is moles per liter? A) mol/(L middot s) B) (L middot s)/mol C) mol^2/(L^2 middot s) D) L^2/(mol^2 middot s) E) L^3/(mol^3 middot s) If a reaction is second-order in a reactant, when the concentration of the reactant is decreased by a factor of 2, the reaction rate will A) remain constant. B) decrease by a factor of 1/4. C) decrease by a factor of 1/2. D) double. E) quadruple. The reaction between selenous acid and the iodide ion in acid solution is H_2SeO_3 (aq) + 6I^- (aq) + 4H^+ (aq) rightarrow Se(s) + 2I_3^- (aq) + 3H_2O(I) The data in the following table were measured at 0 degree C. Tripling the initial concentration of H_2SeO_3 while holding the initial concentrations of H^+ and I^- constant increases the rate of the reaction by a factor of A) 1. B) 2. C) 3. D) 4. E) 8.

Answer 1

Step-by-step explanation:

For the given rate law, Rate = k [ClO_3^-][I^-][H^+]^2, the units of the rate constant (k) can be determined by examining the units of each reactant concentration and the overall rate.

The concentration of ClO_3^- is given in moles per liter (mol/L).

The concentration of I^- is given in moles per liter (mol/L).

The concentration of H^+ is given in moles per liter (mol/L).

The overall rate is given in moles per liter per second (mol/L·s).

By comparing the units, we can determine the units of k:

Rate = k [ClO_3^-][I^-][H^+]^2

mol/(L·s) = k (mol/L)(mol/L)(mol/L)^2

Simplifying the units, we get:

mol/(L·s) = k mol^3/(L^3)

Therefore, the units of k are: mol^2/(L^2·s)

The correct answer is C) mol^2/(L^2·s).

For the second question, if a reaction is second-order in a reactant and the concentration of that reactant is decreased by a factor of 2, the reaction rate will decrease by a factor of 1/2.

The correct answer is C) decrease by a factor of 1/2.

For the third question, if the initial concentration of H_2SeO_3 is tripled while holding the initial concentrations of H^+ and I^- constant, the rate of the reaction will increase by a factor of 2 (doubling).

The correct answer is B) 2.