# Ammonia is produced in the Haber process. The equation for the reaction is: N₂ + 3H₂ → 2NH₃. A student wants to produce ammonia in the laboratory using 5.6 g of nitrogen gas. The relative atomic masses are: N = 14, H = 1. Explain how the student would calculate the theoretical yield of ammonia from this mass of nitrogen, and state the theoretical yield in grams.

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

> The Haber process produces ammonia from nitrogen and hydrogen. In industry, the reaction conditions are 450°C, 200 atm and an iron catalyst. In a laboratory experiment, a student uses 5.6 g of pure nitrogen gas with excess hydrogen gas.

## Mark scheme (5 marks)

1. Calculate the number of moles of nitrogen: moles = mass ÷ Mr = 5.6 ÷ 28 = 0.2 mol
2. Use the molar ratio from the equation: 1 mol N₂ produces 2 mol NH₃, so 0.2 mol N₂ produces 0.4 mol NH₃
3. Calculate the Mr of ammonia (NH₃): Mr = 14 + (3 × 1) = 17
4. Calculate theoretical yield using mass = moles × Mr: mass = 0.4 × 17
5. Correct theoretical yield stated as 6.8 g

## Key terms

- [theoretical yield](https://www.gradenine.co.uk/glossary/theoretical-yield)

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Source: [GradeNine](https://www.gradenine.co.uk/q/ammonia-is-produced-in-the-haber-a36a9124) · Published by Druglandscape Ltd.