(a)Define the term solubility. (b) The table below gives the solubility of salt Z at various mperatures Temperature (°C) 0 10 20 30 40 50 60 Solubility (mol...

(a) Solubility is the maximum amount of a solute that dissolves in 1 dm³ of solution at a specified temperature to form a saturated solution.

(b)(i) The solubility curve of salt Z is plotted below. Temperature is on the horizontal axis and solubility is on the vertical axis.

(ii) From the graph, at 35°C:

Solubility of Z = 0.54 mol dm⁻³.

(iii) From the graph:

• Solubility at 55°C = 0.97 mol dm⁻³
• Solubility at 35°C = 0.54 mol dm⁻³

Decrease in solubility:

\[0.97-0.54=0.43\ \text{mol dm}^{-3}\]

Volume of saturated solution = \(100\text{ cm}^3=0.100\text{ dm}^3\).

Moles of salt crystallized:

\[0.43\times0.100=0.043\ \text{mol}\]

\[\text{Mass crystallized}=0.043\times100=\boxed{4.3\ \text{g}}\]

(c)(i)

I. Reaction with dilute hydrochloric acid:

\[\mathrm{Al_2O_3(s)+6HCl(aq)\rightarrow2AlCl_3(aq)+3H_2O(l)}\]

II. Reaction with sodium hydroxide solution:

\[\mathrm{Al_2O_3(s)+2NaOH(aq)+3H_2O(l)\rightarrow2NaAl(OH)_4(aq)}\]

(c)(ii) Such an oxide is called an amphoteric oxide.

(c)(iii) Zinc oxide, \(\mathrm{ZnO}\), is an amphoteric metallic oxide.

(d)(i)

I. In \(\mathrm{[Al(H_2O)_6]^{3+}}\), water is neutral. Therefore, oxidation number of Al = +3.

II. In \(\mathrm{NaH}\), Na is \(+1\). Therefore, oxidation number of H = −1.

(d)(ii)