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Rate of formation or consumption of one species from that of another, using the coefficients

This type of question, asked 18 times: May 2022 S1, 2 May 2023 S1, 2 May 2023 S2, 3 May 2023 S1, 4 May 2023 S1, 9 May 2023 S1, 9 May 2023 S2, 15 May 2023 S2, 16 May 2023 S2, 9 May 2024 S2, 10 May 2024 S1, 10 May 2024 S2, 11 May 2024 S1, 19 Apr 2025 S1, 23 Apr 2025 S1, 19 Apr 2026 S2, 20 Apr 2026 S1, 12 May 2026 S2. All 18 questions below, oldest first.

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  1. Question 1

    May 2022 S1

    51
    For the reaction N2(g)+3H2(g)→2NH3(g)\text{N}_2(\text{g}) + 3\text{H}_2(\text{g}) \rightarrow 2\text{NH}_3(\text{g}), rate of disappearance of N2(g)\text{N}_2(\text{g}) is 2.22×10−32.22 \times 10^{-3} mol dm−3^{-3}. What is the rate of appearance of NH3(g)\text{NH}_3(\text{g})?

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  2. Question 2

    2 May 2023 S1

    85
    What is the rate of formation of O2\text{O}_2 for the reaction: 2N2O5(g)→4NO2(g)+O2(g)2\text{N}_2\text{O}_5(g) \rightarrow 4\text{NO}_2(g) + \text{O}_2(g), dN2O5dt=0.02\frac{d\text{N}_2\text{O}_5}{dt} = 0.02 mol dm−3^{-3} s−1^{-1}

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  3. Question 3

    2 May 2023 S2

    87
    For the reaction, A+3B⟶2C\text{A} + 3\text{B} \longrightarrow 2\text{C} rate of consumption of A is 1.4 mol dm−3 s−11.4\,\text{mol dm}^{-3}\,\text{s}^{-1}. Calculate rate of formation of C.

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  4. Question 4

    3 May 2023 S1

    95
    For a reaction, 2N2O5(g)⟶4NO2(g)+O2(g)2\text{N}_2\text{O}_5(g)\longrightarrow4\text{NO}_2(g)+\text{O}_2(g), N2O5\text{N}_2\text{O}_5 disappears at a rate of 0.06 mol dm−3 s−10.06\ \text{mol dm}^{-3}\ \text{s}^{-1}. What is rate of NO2(g)\text{NO}_2(g) formation?

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  5. Question 5

    4 May 2023 S1

    86
    For the reaction, 3I−(aq)+S2O82−(aq)→2SO42−(aq)+I3−(aq)3\text{I}^-(aq) + \text{S}_2\text{O}_8^{2-}(aq) \to 2\text{SO}_4^{2-}(aq) + \text{I}_3^-(aq). Rate of formation of SO42−\text{SO}_4^{2-} is 0.044 mol dm−3 s−10.044\text{ mol dm}^{-3}\text{ s}^{-1}. Calculate rate of consumption of I−(aq)\text{I}^-(aq).

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  6. Question 6

    9 May 2023 S1

    80
    Consider the reaction 3I−+S2O82−→I3−+2SO42−3\text{I}^- + \text{S}_2\text{O}_8^{2-} \rightarrow \text{I}_3^- + 2\text{SO}_4^{2-}, at a particular time tt, d[SO42−]dt\frac{d[\text{SO}_4^{2-}]}{dt} is 2.2×10−2 mol dm−3 s−12.2\times10^{-2}\,\text{mol\,dm}^{-3}\,\text{s}^{-1}. What is the value of d[S2O82−]dt\frac{d[\text{S}_2\text{O}_8^{2-}]}{dt}?

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  7. Question 7

    9 May 2023 S2

    81
    For the reaction, N2_2(g) + 3H2_2(g) →\rightarrow 2NH3_3(g). NH3_3 is formed at a rate of 0.088 mol dm−3^{-3} s−1^{-1}. Calculate consumption rate of N2_2(g).

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  8. Question 8

    15 May 2023 S2

    57
    The reaction given below 2NH3(g)→PtN2(g)+3H2(g)2\text{NH}_3(g) \xrightarrow{\text{Pt}} N_2(g) + 3H_2(g) has rate of reaction 2.5×10−6 mol dm−3sec−12.5 \times 10^{-6}\text{ mol dm}^{-3}\text{sec}^{-1} formation of H2(g)H_2(g)?

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  9. Question 9

    16 May 2023 S2

    84
    For the reaction, CH3Br(aq)+OH−(aq)→CH3OH(aq)+Br−(aq)\text{CH}_3\text{Br}(aq) + \text{OH}^-(aq) \rightarrow \text{CH}_3\text{OH}(aq) + \text{Br}^-(aq). Rate of consumption of OH−(aq)\text{OH}^-(aq) is xx mol dm−3^{-3} s−1^{-1}. What is the rate of formation of Br−(aq)\text{Br}^-(aq)?

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  10. Question 10

    9 May 2024 S2

    71
    Find the average rate of formation of O2_2(g) in the following reaction: 2NO2(g)→2NO(g)+O2(g)2\text{NO}_2(\text{g}) \to 2\text{NO}(\text{g}) + \text{O}_2(\text{g}); Δ[NO]Δt=x\frac{\Delta[\text{NO}]}{\Delta t} = x mol dm−3^{-3} s−1^{-1}

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  11. Question 11

    10 May 2024 S1

    87
    For 3I−+S2O82−→I3−+2SO42−3\text{I}^-+\text{S}_2\text{O}_8^{2-}\to\text{I}_3^-+2\text{SO}_4^{2-}, at time t, d[SO42−]dt=2.2×10−2\frac{d[\text{SO}_4^{2-}]}{dt}=2.2\times10^{-2} mol dm−3^{-3} s−1^{-1}. Value of −d[I−]dt-\frac{d[\text{I}^-]}{dt} is

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  12. Question 12

    10 May 2024 S2

    83
    Find the average rate of formation of NO2_2(g) in following reaction. 2N2O5(g)→4NO2(g)+O2(g)2N_2O_5(g)\rightarrow 4NO_2(g)+O_2(g); ΔN2O5Δt=x mol dm−3 s−1\frac{\Delta N_2O_5}{\Delta t}=x\,\text{mol dm}^{-3}\,s^{-1}

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  13. Question 13

    11 May 2024 S1

    60
    For an elementary reaction 2A+B→3C2A + B \rightarrow 3C. Rate of appearance of C is 1.3×10−41.3\times10^{-4} mol L−1^{-1} s−1^{-1}, the rate of disappearance of A is:

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  14. Question 14

    19 Apr 2025 S1

    55
    For the reaction, NO2( g)+CO(g)⟶NO(g)+CO2( g)NO_{2(\text{ }g)}+CO_{(g)}\longrightarrow NO_{(g)}+CO_{2(\text{ }g)}, rate of formation of NO(g)NO_{(g)} is Ymoldmd−3 s−1Ymoldmd^{- 3}{\text{ }s}^{- 1}. Find the rate of disappearance of CO(g)CO_{(g)}.

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  15. Question 15

    23 Apr 2025 S1

    58
    Find the rate of following reaction. 2 N2O5( g)⟶4NO2( g)+O2( g)2{\text{ }N}_{2}O_{5(\text{ }g)}\longrightarrow 4NO_{2(\text{ }g)}+O_{2(\text{ }g)}. if concentration of NO2NO_{2} increases to 5.2×10−3M5.2 \times10^{- 3}M in 100 seconds.

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  16. Question 16

    19 Apr 2026 S2

    32
    Consider the reaction, 3I(aq)−+S2O82−(aq)⟶I3−(aq)+2SO42−(aq)\mathrm{3I^-_{(aq)} + S_2O_8^{2-}{}_{(aq)} \longrightarrow I_3^-{}_{(aq)} + 2SO_4^{2-}{}_{(aq)}} If the rate of formation of SO42−\mathrm{SO_4^{2-}} at a particular time is 2.2×10−2 mol dm−3 s−12.2 \times 10^{-2}\ \mathrm{mol\,dm^{-3}\,s^{-1}}. Calculate the rate of consumption of I−\mathrm{I^-}.

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  17. Question 17

    20 Apr 2026 S1

    31
    In a reaction, 2N2O5(g)→4 NO2(g)+O2(g)\mathrm{2N_2O_{5(g)} \rightarrow 4\,NO_{2(g)} + O_{2(g)}} N2O5\mathrm{N_2O_5} disappears at a rate of 0.06 mol dm−3 s−10.06\ \mathrm{mol\,dm^{-3}\,s^{-1}} Calculate rate of formation of O2(g)\mathrm{O_{2(g)}} ?

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  18. Question 18

    12 May 2026 S2

    28
    Consider the reaction, 2N2O5→4NO2+O2\mathrm{2N_2O_5 \rightarrow 4NO_2 + O_2}. In this reaction, NO2\mathrm{NO_2} is being formed at the rate of 0.0250.025 mol L−1s−1L^{-1}s^{-1}. What would be the rate of reaction?

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