# Silver nitrate solution reacts with sodium chloride solution to produce a white precipitate of silver chloride. The equation for the reaction is: AgNO₃ + NaCl → AgCl + NaNO₃. A student adds excess silver nitrate solution to a sample of sodium chloride solution. The student collects 2.87 g of dry silver chloride precipitate. The relative formula mass (Mr) of silver chloride is 143.5. The relative formula mass (Mr) of sodium chloride is 58.5. Explain how the student can calculate the mass of sodium chloride that reacted, and determine what that mass is.

> Edexcel A-Level Chemistry (9CH0) — 5.1 Calculations using moles · Explain · 5 marks

> Silver nitrate solution reacts with sodium chloride solution to produce a white precipitate of silver chloride. The equation for the reaction is: AgNO₃ + NaCl → AgCl + NaNO₃. A student adds excess silver nitrate solution to a sample of sodium chloride solution and collects 2.87 g of dry silver chloride precipitate. The relative formula mass (Mr) of silver chloride is 143.5 and the relative formula mass (Mr) of sodium chloride is 58.5.

## Mark scheme (5 marks)

1. Divide the mass of silver chloride by its Mr to find moles of silver chloride
2. Moles of silver chloride = 0.02 mol
3. Use the 1:1 molar ratio from the equation to state that moles of NaCl = moles of AgCl
4. Multiply moles of NaCl by its Mr to find mass of NaCl
5. Mass of sodium chloride = 1.17 g

## Key terms

- [relative formula mass](https://www.gradenine.co.uk/glossary/relative-formula-mass)

## Related

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Source: [GradeNine](https://www.gradenine.co.uk/q/silver-nitrate-solution-reacts-with-sodium-d6378c7b) · Published by Druglandscape Ltd.