Question

What are some laboratory methods for determining the rate of reactions?

Answer 1

Here are some of the many methods for determining reaction rates.

Spectrometry

Use a spectrometer to measure the concentration of a component that emits light. For example, you could follow the formation of NO₂ in the reaction

NO(g, colourless) + O₃(g, colourless) → O₂(g, colourless)+ NO₂(g, brown)

by measuring the intensity of the brown colour.

Conductivity

You could measure the change in conductivity of a reaction that produces ions or removes them. For example, you could follow the reaction

(CH₃)₃C-Br(aq) + H₂O(l) → (CH₃)₃C-OH(aq) + H⁺(aq) + Br⁻(aq)

with a conductivity meter.

Potentiometry

You could follow the above reaction by following the change in pH.

Titrimetry

You could follow the same reaction by periodically removing samples of the reaction mixture and titrating them with base to find out how much H⁺ has formed.

Manometry

You could use a manometer to follow the change in pressure of the number of moles of gas changes during the reaction. For example, you could measure the rate of the reaction

Zn(s) + 2CH₃COOH(aq) → Zn²⁺ + 2CH₃COO⁻(aq) + H₂(g)

by measuring the pressure increase as hydrogen is produced.