The rate law for a reaction A + B rightarrow products is rate = k [A]^2. What wi

Question

The rate law for a reaction A + B rightarrow products is rate = k [A]^2. What will be the effect on the reaction rate if the concentration of B is doubled but the concentration of A is unchanged? rate is doubled rate is halved rate is unchanged rate is quadrupled rate is tripled The chemical reaction 5Br(aq) + BrO_3^-(aq) + 6H^+(aq) rightarrow 3Br_2(aq) + 3H_2O(l) has the rate law rate = k[Br][BrO_3^-][H^+]^2. What is the overall order of the reaction? 5 4 3 2 1 The half life of a first order reaction A rightarrow Products is 2.00 min when the initial concentration of A is 1.00 M. What will be the half life of this reaction when the initial concentration of A is 0.500 M? 0.347 min 1.00 min 4.00 min 0.250 min 2.00 min At 184 degree C. the equilibrium constant K is 1.48 times 10^4 for the reaction: 2NO (g) + O_2 (g) 2NO_2 (g) Calculate the value of K for the following reaction: 4NO_2 (g) 4NO (g) + 2O_2 (g) 5.92 times 10^4 6.76 times 10^-5 4.56 times 10^-9 2.19 times 10^8 1.35 times 10^-4 For which of the following reactions are the numerical values for K_p and k the same? 2SO_2(g) + O_2(g) 2SO_3(g) N_2(g) + O_2(g) 2NO(g) H_2(g) + I_2(g) 2HI(g) i only ii only i and ii ii and iii i, ii, and iii

Explanation / Answer

Question 6

Answer C. The reaction rate here only depends on A because the question states that the rate law =k(A)2, so changing B concentration will not affect it (because it's not written in the rate law of the reaction); instead, if we doubled the concentration of A to 2A, the rate of the reaction would be 4 times bigger k(2A)2 = 4kA2..

Question 7

Answer B. The overall reaction rate is the sum of each individual reaction rate for each species involved in the reaction. So if the reaction rate = k(Br-)1(BrO3-)1(H+)2 let's remember that the semi-reaction rates are written as exponents of the concentrations of each species; thus 1+1+2 = 4.

Question 8

Answer E. Half-life isn't affected by initial concentration when the reaction order is one. Let's remember that the formula for half-life in first order reactions is:

t(1/2) = ln2/k

As we can see here, half-life of first order reactions only depends on the constant k.

Question 9

Answer B. Using Hess law, the K of the inverse reaction will be 1/K. The coefficients being doubled doesn't affect K.

For example:

For the reaction:

A+B->C k=10

Then, for the inverse reaction:

C->A+B k=0.1

If the reverse reaction is doubled:

2C-> 2A + 2B k=0.1

The reaction being doubled doesn't affect the constant (unlike with deltaH, which actually doubles).

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