A student is investigating the rate of the reaction between peroxodisulfate ions and iodide ions in aqueous solution:
S2O82−(aq)+2I−(aq)→2SO42−(aq)+I2(aq) \text{S}_2\text{O}_8^{2-}(\text{aq}) + 2\text{I}^-(\text{aq}) \rightarrow 2\text{SO}_4^{2-}(\text{aq}) + \text{I}_2(\text{aq}) S2O82−(aq)+2I−(aq)→2SO42−(aq)+I2(aq)Which of the following is the most suitable method for continuously monitoring the rate of this reaction?
Monitoring the change in pH of the reaction mixture over time using a pH probe.
Measuring the volume of gas evolved over time using a gas syringe.
Monitoring the decrease in mass of the reaction vessel over time using a balance.
Measuring the absorbance of the solution over time using a colorimeter.
91 exam-style questions on OCR GCSE Chemistry Monitoring chemical reactions. Each one has a worked solution and a mark scheme showing where the marks go.