Ncert Exercises & Solutions

Question 10.17:

What happens when

(i) magnesium is burnt in air

(ii) quick lime is heated with silica

(iii) chlorine reacts with slaked lime

(iv) calcium nitrate is heated?

(i) Magnesium burns in air with a dazzling light to form MgO and Mg₃N₂.

2 Mg + O_{2} \overset{Burning}{\to} 2 MgO

3 Mg + N_{2} \overset{Burning}{\to} {Mg}_{3} N_{2}

(ii) Quick lime (CaO) combines with silica (SiO₂) to form slag.

CaO + {SiO}_{2} \overset{heat}{\to} {CaSiO}_{3}

(iii) When chloride is added to slaked lime, it gives bleaching powder.

Ca {(OH)}_{2} + {Cl}_{2} \overset{∆}{\to} \underset{Bleaching}{{CaOCl}_{2}}

powder + H_{2} O

(iv) Calcium nitrate, on heating, decomposes to give calcium oxide.

2 Ca {({NO}_{3})}_{2 (s)} \overset{∆}{\to} 2 {CaO}_{(s)} + 4 {NO}_{2 (g)} + O_{2 (g)}