Rates 2.2.1

Question 1

What is the general equation for a rate of a reaction?

Answer 1

ΔP / Δt or -ΔR / Δt

Question 2

Concentration of reactants vs rate

Answer 2

The faster the concentration of the reactants decreases, the faster the rate of the reaction

Question 3

How to find the average rate of a reaction?

Answer 3

Use the gradient formula

Question 4

Measuring the rate by the change in the volume of gas produced

Answer 4

You create a volume vs time graph from this data

Method 1: a gas syringe is collects gas and the barrel records the volume

Method 2: Downward displacement of water
Can be only used for gases that have a low solubility in water

Method 3: Data loggers that create graphs

Question 5

Measuring the rate by the change in mass

Answer 5

If a reaction gives a gas, the reaction mixture can be measures on a balance (can’t be done with H2 because too light)

Question 6

Measuring the rate by change in transmission of light (colorimetry/spectrophotometry)

Answer 6

Can be used if one of the reactants or products is colour
An indicator can be added to generate a coloured compound that can be followed in the reaction
Light of a selected wavelength is passed through the solution
It then measure the intensity of light transmitted
As the concentration of a coloured compound increases, it absorbs more light so less is transmitted
The method allows for continuous reading to be made, so a graph of absorbance against time can be plotted