Chemical Kinetics Chapter-Wise Test 8

Correct answer Carries: 4.

Wrong Answer Carries: -1.

A reaction follows zero-order kinetics with a rate constant of \( 4.0 \times 10^{-4} \, \text{mol L}^{-1} \text{s}^{-1} \). If the initial concentration is \( 0.08 \, \text{mol L}^{-1} \), what is the time required for complete decomposition?

For a zero-order reaction, \( t = \frac{[\text{R}]_0}{k} \) when \( [\text{R}] = 0 \).

Given: \( k = 4.0 \times 10^{-4} \, \text{mol L}^{-1} \text{s}^{-1} \), \( [\text{R}]_0 = 0.08 \, \text{mol L}^{-1} \).

\( t = \frac{0.08}{4.0 \times 10^{-4}} = 200 \, \text{s} \).

200 s
250 s
300 s
150 s
1

For the reaction \( \text{A} + 3\text{B} \to 2\text{C} \), the rate of disappearance of B is \( 0.09 \, \text{mol L}^{-1} \text{s}^{-1} \). What is the rate of formation of C?

Rate = \( -\frac{1}{3} \frac{\Delta[\text{B}]}{\Delta t} = \frac{1}{2} \frac{\Delta[\text{C}]}{\Delta t} \).

Given: \( -\frac{\Delta[\text{B}]}{\Delta t} = 0.09 \, \text{mol L}^{-1} \text{s}^{-1} \).

Rate = \( \frac{0.09}{3} = 0.03 \), \( \frac{\Delta[\text{C}]}{\Delta t} = 2 \times 0.03 = 0.06 \, \text{mol L}^{-1} \text{s}^{-1} \).

0.06 mol L\(^{-1}\) s\(^{-1}\)
0.09 mol L\(^{-1}\) s\(^{-1}\)
0.03 mol L\(^{-1}\) s\(^{-1}\)
0.12 mol L\(^{-1}\) s\(^{-1}\)
1

A first-order reaction has a rate constant of \( 0.0139 \, \text{min}^{-1} \). What is the time for 60% completion?

For first-order, \( t = \frac{2.303}{k} \log \frac{[\text{R}]_0}{[\text{R}]} \).

60% complete means 40% remains, \( \frac{[\text{R}]}{[\text{R}]_0} = 0.4 \), \( \frac{[\text{R}]_0}{[\text{R}]} = \frac{1}{0.4} = 2.5 \).

\( t = \frac{2.303}{0.0139} \log 2.5 = \frac{2.303 \times 0.398}{0.0139} \approx 66 \, \text{min} \).

50 min
60 min
66 min
75 min
3

For the reaction \( 2\text{A} + \text{B} \to 4\text{C} \), the rate of formation of C is \( 0.16 \, \text{mol L}^{-1} \text{min}^{-1} \). What is the rate of disappearance of A?

Rate = \( -\frac{1}{2} \frac{\Delta[\text{A}]}{\Delta t} = \frac{1}{4} \frac{\Delta[\text{C}]}{\Delta t} \).

Given: \( \frac{\Delta[\text{C}]}{\Delta t} = 0.16 \, \text{mol L}^{-1} \text{min}^{-1} \).

Rate = \( \frac{0.16}{4} = 0.04 \), \( -\frac{\Delta[\text{A}]}{\Delta t} = 2 \times 0.04 = 0.08 \, \text{mol L}^{-1} \text{min}^{-1} \).

0.08 mol L\(^{-1}\) min\(^{-1}\)
0.04 mol L\(^{-1}\) min\(^{-1}\)
0.16 mol L\(^{-1}\) min\(^{-1}\)
0.12 mol L\(^{-1}\) min\(^{-1}\)
1

A zero-order reaction has a rate constant of \( 4.0 \times 10^{-3} \, \text{mol L}^{-1} \text{min}^{-1} \). If the initial concentration is \( 0.16 \, \text{mol L}^{-1} \), how long will it take for 50% decomposition?

For zero-order, \( t_{1/2} = \frac{[\text{R}]_0}{2k} \).

Given: \( [\text{R}]_0 = 0.16 \, \text{mol L}^{-1} \), \( k = 4.0 \times 10^{-3} \, \text{mol L}^{-1} \text{min}^{-1} \).

\( t_{1/2} = \frac{0.16}{2 \times 4.0 \times 10^{-3}} = \frac{0.16}{8.0 \times 10^{-3}} = 20 \, \text{min} \).

20 min
30 min
40 min
15 min
1

For the reaction \( 2\text{A} \to \text{B} \), the rate of disappearance of A is \( 0.04 \, \text{mol L}^{-1} \text{min}^{-1} \). What is the rate of formation of B?

Rate of reaction = \( -\frac{1}{2} \frac{\Delta[\text{A}]}{\Delta t} = \frac{\Delta[\text{B}]}{\Delta t} \).

Given: \( -\frac{\Delta[\text{A}]}{\Delta t} = 0.04 \, \text{mol L}^{-1} \text{min}^{-1} \).

Rate = \( \frac{0.04}{2} = 0.02 \, \text{mol L}^{-1} \text{min}^{-1} \), so \( \frac{\Delta[\text{B}]}{\Delta t} = 0.02 \, \text{mol L}^{-1} \text{min}^{-1} \).

0.02 mol L\(^{-1}\) min\(^{-1}\)
0.04 mol L\(^{-1}\) min\(^{-1}\)
0.08 mol L\(^{-1}\) min\(^{-1}\)
0.01 mol L\(^{-1}\) min\(^{-1}\)
1

The molecularity of the elementary step \( \text{Cl}_2 + \text{CHCl}_3 \to \text{HCl} + \text{CCl}_4 \) is:

Molecularity is the number of molecules in an elementary step.

For \( \text{Cl}_2 + \text{CHCl}_3 \), two molecules collide, so molecularity = 2.

1
2
3
4
2

For the reaction \( \text{A} + \text{B} \to 2\text{C} \), the rate of disappearance of B is \( 0.06 \, \text{mol L}^{-1} \text{s}^{-1} \). What is the rate of formation of C?

Rate = \( -\frac{\Delta[\text{B}]}{\Delta t} = \frac{1}{2} \frac{\Delta[\text{C}]}{\Delta t} \).

Given: \( -\frac{\Delta[\text{B}]}{\Delta t} = 0.06 \, \text{mol L}^{-1} \text{s}^{-1} \).

\( \frac{\Delta[\text{C}]}{\Delta t} = 2 \times 0.06 = 0.12 \, \text{mol L}^{-1} \text{s}^{-1} \).

0.06 mol L\(^{-1}\) s\(^{-1}\)
0.12 mol L\(^{-1}\) s\(^{-1}\)
0.03 mol L\(^{-1}\) s\(^{-1}\)
0.18 mol L\(^{-1}\) s\(^{-1}\)
2

For the reaction \( 2\text{A} + 3\text{B} \to 4\text{C} \), the rate of formation of C is \( 0.08 \, \text{mol L}^{-1} \text{min}^{-1} \). What is the rate of disappearance of A?

Rate = \( -\frac{1}{2} \frac{\Delta[\text{A}]}{\Delta t} = \frac{1}{4} \frac{\Delta[\text{C}]}{\Delta t} \).

Given: \( \frac{\Delta[\text{C}]}{\Delta t} = 0.08 \, \text{mol L}^{-1} \text{min}^{-1} \).

Rate = \( \frac{0.08}{4} = 0.02 \), \( -\frac{\Delta[\text{A}]}{\Delta t} = 2 \times 0.02 = 0.04 \, \text{mol L}^{-1} \text{min}^{-1} \).

0.04 mol L\(^{-1}\) min\(^{-1}\)
0.08 mol L\(^{-1}\) min\(^{-1}\)
0.02 mol L\(^{-1}\) min\(^{-1}\)
0.06 mol L\(^{-1}\) min\(^{-1}\)
1

A reaction has the rate law \( \text{Rate} = k[\text{A}]^{1/2}[\text{B}]^{3/2} \). What is the overall order?

Overall order = \( \frac{1}{2} + \frac{3}{2} = \frac{1}{2} + \frac{3}{2} = 2 \).

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1.5
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2
4

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