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Rate, rate constant, concentration or half-life from rate = k[A] or k[A]^2 for one reactant

This type of question, asked 10 times: 4 May 2023 S2, 10 May 2023 S2, 10 May 2024 S2, 11 May 2024 S1, 16 Apr 2026 S1, 17 Apr 2026 S2, 18 Apr 2026 S1, 20 Apr 2026 S2, 12 May 2026 S1, 14 May 2026 S2. All 10 questions below, oldest first.

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  1. Question 1

    4 May 2023 S2

    83
    For the reaction 2N2O5(g)→4NO2(g)+O2(g)2N_2O_5(g)\rightarrow 4NO_2(g)+O_2(g), rate and rate constant are 1.02×10−41.02\times10^{-4} mol L⁻¹ s⁻¹ and 3.4×10−53.4\times10^{-5} s⁻¹. What is the conc. of N₂O₅?

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  2. Question 2

    10 May 2023 S2

    86
    Rate of a first order reaction is 1.5×10−2 mol L−1 minute−11.5 \times 10^{-2}\,\text{mol}\,\text{L}^{-1}\,\text{minute}^{-1} at 0.5 M concentration of reactant, calculate half life of reaction.

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  3. Question 3

    10 May 2024 S2

    65
    Calculate the rate constant for the first order reaction, A→BA\rightarrow B if the rate of reaction is 5.4×10−6 mol dm−35.4\times10^{-6}\,\text{mol dm}^{-3} and [A]=0.3 M[A]=0.3\,M

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  4. Question 4

    11 May 2024 S1

    81
    What is half life time of a first order reaction if initial conc. of reactant is 0.01 mol L−1^{-1} and rate of reaction is 0.003520.00352 mol L−1^{-1} minute−1^{-1}?

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  5. Question 5

    16 Apr 2026 S1

    31
    The rate constant for the reaction 2N2O5→4NO2+O2\mathrm{2N_2O_5 \rightarrow 4NO_2 + O_2} is 3.0×10−5 s−13.0 \times 10^{-5}\ \mathrm{s^{-1}}. If the rate is 2.4×10−52.4 \times 10^{-5} mole L−1 s−1\mathrm{L^{-1}\,s^{-1}} then the concentration of N2O5\mathrm{N_2O_5} (mol L−1\mathrm{L^{-1}}) is

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  6. Question 6

    17 Apr 2026 S2

    28
    For the reaction 2NOBr(g)→2NO(g)+Br2(g)\mathrm{2NOBr_{(g)} \rightarrow 2NO_{(g)} + Br_{2(g)}} rate law is r=k[NOBr]2r = k[\mathrm{NOBr}]^2, if rate constant is 1.62 mol dm−3 s−11.62\ \mathrm{mol\,dm^{-3}\,s^{-1}} and concentration of NOBr is 2×10−3 mol L−12 \times 10^{-3}\ \mathrm{mol\,L^{-1}}. What is the rate of reaction ?

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  7. Question 7

    18 Apr 2026 S1

    28
    For the reaction 2NOBr(g)⟶2NO(g)+Br2(g)\mathrm{2NOBr_{(g)} \longrightarrow 2NO_{(g)} + Br_{2(g)}}, rate law is r=k[NOBr]2r = k[\mathrm{NOBr}]^2. Rate constant is 1.62 M s−11.62\ \mathrm{M\,s^{-1}} and concentration of NOBr is 5×10−35 \times 10^{-3} M, What is rate of reaction?

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  8. Question 8

    20 Apr 2026 S2

    29
    Calculate the rate constant of first order reaction A→B\mathrm{A \rightarrow B} having rate 5.4×10−6 mol dm−3s−15.4 \times 10^{-6}\ \mathrm{mol\,dm^{-3}s^{-1}} and [A]=0.3[\mathrm{A}] = 0.3 M.

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  9. Question 9

    12 May 2026 S1

    26
    In a reaction, 2A(g)→\mathrm{2A_{(g)} \rightarrow} Products, the rate law is r=k[A]2r = k[A]^2. Calculate the rate constant if the rate of reaction is 6.5×10−66.5 \times 10^{-6} mol L−1 S−1\mathrm{L^{-1}\,S^{-1}} and [A][A] is 2×10−32 \times 10^{-3} mol/L.

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  10. Question 10

    14 May 2026 S2

    27
    A first order reaction has a half life period 69.369.3 seconds. Calculate the rate of reaction if the concentration of reactant is 0.10.1 M.

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