12. Nitrogen and sulfur
A section of Chemistry, 9701
Listing 10 of 350 questions
Nitrogenmonoxide, NO, reacts with oxygen to form nitrogendioxide, NO2. 2NO+ O22NO2The rate equation for the forward reaction is shown. rate = k2 Complete the following table. the order of reaction with respect to the order of reaction with respect to the overall order of reaction  Two separate experiments are carried out at 30 °C to determine the rate of the forward reaction. experiment / mol dm–3 / mol dm–3 rate / mol dm–3 s–1 0.00300 0.00200 1.51 × 10–4 0.00500 6.05 × 10–5 Use the data for experiment1 to calculate the value of the rate constant, k. State the units of k.  k = units =  Calculate the value of in experiment2.  = mol dm–3 Define the term rate-determining step. Peroxodisulfate ions, S2O8 2–, react with iodide ions, I–. S2O8 2– + 2I– → 2SO4 2– + I2 The rate equation for the reaction in the absence of any catalyst is shown. rate = k[S2O8 2–][I–] Suggest equations for a two-step mechanism for this reaction, stating which of the two steps is the rate-determining step. step 1 step 2 rate-determining step =  A large excess of peroxodisulfate ions is mixed with iodide ions. Immediately after mixing, [I–]=0.00780 mol dm–3. Under the conditions used, the half-life of [I–] is 48seconds. Calculate the iodide ion concentration 192seconds after the peroxodisulfate and iodide ions are mixed.  iodide ion concentration = mol dm–3 
9701_w20_qp_41
THEORY
2020
Paper 4, Variant 1
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Questions Discovered
350