Orders, rate equations and rate constants
(a) explanation and use of the terms: rate of reaction, order, overall order, rate constant, half-life, rate-determining step
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(b) deduction of:
(i) orders from experimental data
(ii) ) a rate equation from orders of the form: rate = k[A]m[B]n, where m and n are 0, 1 or 2
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(c) calculation of the rate constant, k, and related quantities, from a rate equation including determination of units
Rate graphs and orders
(d) from a concentration–time graph:
(i) deduction of the order (0 or 1) with respect to a reactant from the shape of the graph
(ii) calculation of reaction rates from the measurement of gradients (see also 3.2.2 b)
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(e) from a concentration–time graph of a first order reaction, measurement of constant half-life, t1/2
(f) for a first order reaction, determination of the rate constant, k, from the constant half-life, t 1/2, using the relationship: k = ln 2/t 1/2
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(g) from a rate–concentration graph:
(i) deduction of the order (0, 1 or 2) with respect to a reactant from the shape of the graph
(ii) determination of rate constant for a first order reaction from the gradient
(h) the techniques and procedures used to investigate reaction rates by the initial rates method and by continuous monitoring, including use of colorimetry (see also 3.2.2 e)
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Rate-determining step
(i) for a multi-step reaction, prediction of
(i) a rate equation that is consistent with the rate-determining step
(ii) possible steps in a reaction mechanism from the rate equation and the balanced equation for the overall reaction
Effect of temperature on rate constants
(j) a qualitative explanation of the effect of temperature change on the rate of a reaction and hence the rate constant (see 3.2.2 f–g)
(k) the Arrhenius equation:
(i) ) the exponential relationship between the rate constant, k and temperature, T given by the Arrhenius equation, k = Ae–Ea/RT
(ii) determination of Ea and A graphically using: ln k = –Ea/RT + ln A derived from the Arrhenius equation.