10.1 The four steps in the manufacture of an inorganic fertiliser are listed below - NSC Physical Sciences - Question 10 - 2019 - Paper 2

The balanced chemical equation for step I is:

The catalyst used in step II is Vanadium pentoxide (V2O5).

The balanced chemical equation for step IV is:

Sulphur trioxide is not dissolved in water in step IV because the reaction is highly exothermic, which can produce corrosive mists and lead to hazardous conditions.

To calculate the value of X, we can use the NPK ratio that typically follows the formula for fertilisers:

If the bag is labelled N-P-K (20-10-X) and the potassium mass is 3.33 kg, we can find the ratio as follows:

Given that:

• N: 20%
• P: 10%
• K: X%

Letting the total mass of the fertiliser be 50 kg, we apply the ratio:

$X = (3.33 ext{ kg K} / 50 ext{ kg}) imes 100$ Thus, we can deduce:

$X = 6.66$ Therefore, the value of X is 6.66.