Fertilisers are formulations - AQA - GCSE Chemistry Combined Science - Question 4 - 2018 - Paper 2

First, convert the mass of ammonium nitrate from kilograms to grams:

$m = 14.52 ext{ kg} = 14,520 ext{ g}$

Using the relative formula mass of ammonium nitrate, which is 80 g/mol, the number of moles can be calculated as follows:

ext{Moles} = rac{mass}{M} = rac{14,520 ext{ g}}{80 ext{ g/mol}} = 181.5 ext{ mol}

To express this in standard form to 2 significant figures:

$= 1.8 imes 10^2 ext{ mol}$

Potassium chloride has a high melting point because it forms a giant ionic lattice structure. The ionic bonds between the positively charged potassium ions (K⁺) and negatively charged chloride ions (Cl⁻) require a large amount of energy to overcome. Furthermore, the strong electrostatic attractions between these ions contribute significantly to the thermal stability of the structure.