# 4.6.1.1

4.6.1.1 Calculating rates of reactions

## Content

• The rate of a chemical reaction can be found by measuring the quantity of a reactant used or the quantity of product formed over time: The quantity of reactant or product can be measured by the mass in grams or by a volume in cm3.

The units of rate of reaction may be given as g/s or cm3/s.

For the Higher Tier, students are also required to use quantity of reactants in terms of moles and units for rate of reaction in mol/s.

Students should be able to:

• calculate the mean rate of a reaction from given information about the quantity of a reactant used or the quantity of a product formed and the time taken
• draw, and interpret, graphs showing the quantity of product formed or quantity of reactant used up against time
• draw tangents to the curves on these graphs and use the slope of the tangent as a measure of the rate of reaction
• (HT only) calculate the gradient of a tangent to the curve on these graphs as a measure of rate of reaction at a specific time.

MS 1a - Recognise and use expressions in decimal form

MS 1c Use ratios, fractions and percentages

MS 1d Make estimates of the results of simple calculations

MS 4a Translate information between graphical and numeric form

MS 4b Understand that y = mx + c represents a linear relationship

MS 4c Plot two variables from experimental or other data

MS 4d Determine the slope and intercept of a linear graph

MS 4e Draw and use the slope of a tangent to a curve as a measure of rate of change