How can measuring half-life indicate if a reaction is first order?

Measure successive half-lives; if they are the same, the reaction is first order.

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What is the formula that links rate constant (k) and half-life (t12\frac{1}{2}) of a first-order reaction?

k =t21​​ln2​


k = rate constant (s-1)

t12\frac{1}{2} = half-life (s)

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How is a calibration curve prepared in colorimetry?

Prepare standard solutions with known concentrations, measure their absorbance, plot absorbance vs. concentration, and fit a trendline to obtain the calibration curve.

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What is a clock reaction?

A clock reaction is a type of reaction used to estimate initial rates by measuring the time taken for a clear observable change, such as a colour change, to occur. The shorter the time taken for the change to occur, the higher the initial rate.

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How is the initial rate determined in the initial rates method?

The initial rate is determined by calculating the gradient of a tangent drawn at time = 0 on a concentration-time graph.

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What is meant by the half-life of a reaction?

The half-life of a reaction is the time it takes for the concentration of a reactant to decrease to half of its original value.

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What are the typical shapes of rate vs. concentration graphs for zero, first, and second order reactions?

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What are the typical shapes of concentration vs. time graphs for zero, first, and second order reactions?

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How are iodine clocks used in determining reaction rates?

Iodine clocks are used to measure the initial rate of a reaction by timing how long it takes from the start of the reaction for the blue-black colour to appear (t). The initial rate of reaction is inversely proportional to the time taken for the colour change to occur (t1​).

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How are unknown sample concentrations determined using a calibration curve in colorimetry?

Unknown sample concentrations can be determined by locating their absorbance on the calibration curve and reading the corresponding concentration from the x-axis.

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