PRE QUIZ G4 ASC0305

Consider the following reaction,

At a certain temperature the rate of decomposition of N2O5 is 2.5 ×10-6 mol/s. The rate of formation of NO2 is:

• 1.0 ×10-5 mol/s

• 1.3 ×10-6 mol/s

• 2.5 ×10-6 mol/s

• 5.0 ×10-6 mol/s

Consider the following reaction: The rate of this reaction could be increased by..............

• decreasing temperature.

• adding a catalyst.

• increasing the concentration of S(s)

• increasing the concentration of SO3(g)

The rate law for the reaction is:

• Rate = k[NH₄⁺][NO₂^-]

• Rate = k[NH₄⁺]²[NO₂^-]²

• Rate = k[NH₄⁺]²[NO₂^-]

• Rate = k[NH₄⁺][NO₂^-]²

Given: A + 3B --> 2C + D

This reaction is first order with respect to reactant A and second order with respect to reactant B. If the concentration of A is doubled and the concentration of B is halved, the rate of the reaction would _____ by a factor of _____.

• increase, 2

• decrease, 2

• increase, 4

• decrease, 4

The decomposition of carbon disulfide, CS₂, to carbon monosulfide, CS, and sulfur is first order with k = 2.8 x 10^-7 s^-1 at 1000^oC.

CS₂ --> CS + S

What is the half-life of this reaction at 1000^oC?

• 2.5 x 10⁶ s

• 5.0 x 10⁷ s

• 3.8 x 10⁵ s

• 6.1 x 10⁴ s

The half-life for a first-order reaction is 32 s.

What was the original concentration if, after 2.0 minutes, the reactant concentration is 0.062 M?

• 0.075 M

• 0.84 M

• 0.13 M

• 0.091 M

Suppose the reaction: A + 2B AB₂ occurs by the following mechanism:

Step 1A + B --> AB (slow)

Step 2AB + B --> AB2 (fast)

Overall A + 2B --> AB2

The rate law expression must be Rate = _________.

• k[B]²

• k[A][B]²

• k[A]

• k[A][B]

Suppose the activation energy of a certain reaction is 250 kJ/mol.

If the rate constant at T₁ = 300 K is k₁ and the rate constant at T₂ = 320 K is k₂,

then the reaction is __ times faster at 320 K than at 300 K. (Hint: Solve for k₂/k₁.)

• 525

• 3 x 10^-29

• 15.0

• 0.067

Which of the following statements about catalysts is false:

• catalysts do not appear in the balanced equation

• catalysts reduce the activation energy for a reaction

• catalysts do not alter the mechanism of the reaction and never appear in the rate law

• biological catalysts are called enzymes

The initial rate data for the reaction 2N2O5(g) → 4NO2(g) + O2(g) is shown in the following table.

Determine the value of the rate constant for this reaction.

• 0.225 s –1

• 4.09 s –1

• 80.1 s –1

• 0.176 s–1