# 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.

## Slide deck

## 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.

### 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.

### Keywords

Balanced symbol equation - A balanced symbol equation describes a reaction using a symbol equation with coefficients, which ensure there are equal numbers of atoms of each element on both sides of the symbol equation.

Conservation of mass - Conservation of mass means that the combined mass of the starting reactants equals the combined mass of the products formed.

Relative formula mass - The relative formula mass (RFM) of a substance is the sum of the relative atomic masses of all the atoms in a 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.

### Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

## Video

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## Worksheet

## 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