Question

The rate of a chemical reaction depends on the concentrations of the reactants. Let's consider the general reaction between A and B: aA+bB⇌cC+dD The dependence of the reaction rate on the concentration of each reactant is given by the equation called the rate law: rate=k[A]m[B]n where k is a proportionality constant called the rate constant. The exponent m determines the reaction order with respect to A, and n determines the reaction order with respect to B. The overall reaction order equals the sum of the exponents (m+n). For example, if m = 2 and n = 2 then rate = k[A]2 [B]2 and the overall reaction order is 2 + 2 = 4. The reaction orders are experimentally determined and usually not related to the reaction stoichiometric coefficients a and b. The reaction of ethyl bromide with sodium hydroxide, CH3CH2Br(aq) + NaOH(aq) CH3CH2 OH(aq) + NaBr(aq) is first order in CH3CH2Br and first order in NaOH . If the concentration of CH3CH2Br was increased by half and the concentration of NaOH was quadrupled, by what factor would the reaction rate increase? Express your answer numerically.

Answer 1

Answer:

Ex6  planation:

CH₃CH₂Br + OH⁻ ⟶ CH₃CH₂OH + Br⁻

Let's rewrite the equation as

A + B ⟶ C + D

m = 1 and n = 1, so the rate law is

r = k[A][B]

For a first order reaction, the rate is directly proportional to the concentration.

If you increase [A] by half, you increase the rate by a factor of 1.5.

If you quadruple [B], you increase the rate by a factor of 4.

If you do both, you multiply the factors: 1.5 × 4 = 6.

The rate will increase by a factor of 6.