Mass in a chemical reaction
I can use conservation of mass and relative formula masses to predict the mass of unknown products or reactants.
Mass in a chemical reaction
I can use conservation of mass and relative formula masses to predict the mass of unknown products or reactants.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- In a chemical reaction, the atoms in reactants are rearranged and are the same atoms that are in the products.
- The mass of products in a chemical reaction is equal to the mass of the reactants.
- The sum of the RFM of the reactants equals the sum of the RFM of the products, taking account of balancing coefficients.
Keywords
Balanced symbol equation - A balanced symbol equation represents a chemical reaction using symbols and coefficients to ensure that the number of atoms of each element is equal on both sides of the equation.
Conservation of mass - Conservation of mass means the total mass of the starting reactants equals the total mass of the products formed.
Relative formula mass - The relative formula mass (RFM or Mᵣ) of a substance is the sum of the relative atomic masses of all the atoms in its formula.
Coefficient - A coefficient is the number placed in front of a chemical formula to balance an equation; it multiplies all the atoms in the formula and shows the ratio of substances in a reaction.
Common misconception
Pupils struggle to recall the order of steps required to mathematically process the available information in order to answer the question.
Colour-coding the steps can help pupils remember how many steps are involved. Much practice and perseverance is needed to create and maintain the memory pathway of the mathematical processing.
To help you plan your year 10 combined science lesson on: Mass in a chemical reaction, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 10 combined science lesson on: Mass in a chemical reaction, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 4 combined science lessons from the Calculations involving masses unit, dive into the full secondary combined science curriculum, or learn more about lesson planning.
Equipment
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Lesson video
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Starter quiz
6 Questions
Exit quiz
6 Questions
describes the numbers of atoms taking part in a reaction
in a chemical reaction mass is neither created nor destroyed
the sum of the relative atomic masses of all atoms in a formula
the number placed in front of a formula in an equation