Moles and Masses
Count the atoms in a formula to find its Mr, then use it: moles from a mass, a mass from moles, and reacting masses.
About this activity
Students count the atoms in three formulae (the last has brackets) while the relative formula mass adds up beside them. Then they use moles = mass ÷ Mr both ways round with a formula triangle, and finish with a reacting-mass question taken a step at a time. The formulae and numbers change every time. The first screen says how this fits the student’s exam board: on AQA, the moles questions are Higher tier only.
How to use Moles and Masses
- Moles and Masses is a free Chemistry activity for Years 10 to 11 that takes about 12 minutes. Try it on this page on a computer, tablet or phone: there’s nothing to download.
- In a lesson, choose Show on the board to play it together as a class.
- To set it for a class, a teacher shares it and gets a code: students type the 6-digit code at lycolearn.co.uk/join with their first name and the first letter of their surname (no accounts needed), and their scores come back to the teacher.
Students will
- Calculate a relative formula mass, including formulae with brackets
- Calculate moles from a mass, and a mass from moles
- Calculate the mass of a product from a balanced equation
Teaching tips
- Parts 1 to 3 (relative formula mass) suit every student; parts 4 to 6 are the Higher tier moles work on AQA.
- Have calculators out: the answers are typed, and one wrong go gets a hint before the answer is shown.