Ammonium nitrate is an important fertiliser - NSC Physical Sciences - Question 10 - 2016 - Paper 2

The two products formed in the catalytic oxidation of ammonia are nitrogen monoxide (NO) and water (H₂O).

The balanced equation for the preparation of ammonium nitrate is:

$NH_3 + HNO_3 \rightarrow NH_4NO_3$

To find the mass of ammonium nitrate produced from 6.8 x 10^4 kg of ammonia, we first need to convert the mass of ammonia to moles:

• Molar mass of ammonia (NH₃) = 17 g/mol
• Moles of ammonia = ( \frac{6.8 \times 10^4 ext{ kg} \times 10^3 ext{ g/kg}}{17 ext{ g/mol}} = 4.0 \times 10^6 ext{ mol} )

Since one mole of ammonia produces one mole of ammonium nitrate, we produce P 4.0 x 10^6 mol of ammonium nitrate.

Now, calculating the mass of ammonium nitrate:

• Molar mass of ammonium nitrate (NH₄NO₃) = 80 g/mol
• Mass = moles × molar mass = ( 4.0 \times 10^6 ext{ mol} \times 80 ext{ g/mol} = 3.2 \times 10^8 ext{ g} = 3.2 \times 10^5 ext{ kg} )

Ammonium nitrate is mixed with potassium chloride and ammonium phosphate to create a balanced NPK (Nitrogen, Phosphorus, Potassium) fertiliser, which contains all three primary nutrients necessary for plant growth.