Question

What happens when?
$(i)$ Magnesium is burnt in air
$(ii)$ Quick lime is heated with silica
$(iii)$ Chlorine react with slaked lime
$(iv)$ Calcium nitrate is heated

Answer 1

Hint – In this question the concept that burnt air means that we are reacting the compound with oxygen (O2) and nitrogen (N2) present in the air. CaO is the chemical formula for quick lime and silica is (SiO2). The chemical formula for slaked lime is $Ca{(OH)_2}$. Calcium nitrate is $Ca{(N{O_3})_2}$. Use them to formulate the chemical reactions to get the products.

Complete answer:
$\left( i \right)$ When magnesium (MgO) is burnt in air it reacts with oxygen (O2) and nitrogen (N2)present in the air and forms a magnesium oxide (MgO) and magnesium nitride (Mg3N2) , the chemical reaction is given below,
\[ \Rightarrow 5Mg + {O_2} + {N_2}\xrightarrow{{{\text{burnt}}}}2MgO + M{g_3}{N_2}\]
$\left( {ii} \right)$ When quick lime (CaO) is heated with silica (SiO2) calcium silicate (CaSiO3) is formed, the chemical reaction is given below,
\[ \Rightarrow CaO + Si{O_2}\xrightarrow{{{\text{heated}}}}CaSi{O_3}\]
$\left( {iii} \right)$ When chlorine (Cl) reacts with slaked lime Ca (OH)2 calcium hypochlorite $\left[ {CaC{l_2} + Ca{{\left( {OCl} \right)}_2}} \right]$ is formed which is a constituent of a bleaching powder, the chemical reaction is given below,
$ \Rightarrow 2Ca{\left( {OH} \right)_2} + 2C{l_2}\xrightarrow{{}}CaC{l_2} + Ca{\left( {OCl} \right)_2} + 2{H_2}O$
$\left( {iv} \right)$ When calcium nitrate Ca(NO3)2 is heated calcium oxide (CaO), nitrogen-dioxide (NO2) and oxygen is released, the chemical reaction is given below,
$ \Rightarrow 2Ca{\left( {N{O_3}} \right)_2}\xrightarrow{{{\text{heated}}}}2CaO + 4N{O_2} + {O_2}$
So this is the required answer.

Note – The concerning point is regarding the by-product formulation of chemical equations on reacting reactants always form the main product along with the by-products just like in chemical reaction $2Ca{\left( {OH} \right)_2} + 2C{l_2}\xrightarrow{{}}CaC{l_2} + Ca{\left( {OCl} \right)_2} + 2{H_2}O$, bleaching powder is formed however water is also formed as the by-product. Equation balancing is very important. The key logic behind it is that the number of atoms for each element in the reaction and the total charge is the same both the reactants that are on the left side of the equation and the products that are on the right side of the equation.