Question

${\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{aq}\right)+\mathrm{NaOH}\left(\mathrm{aq}\right)\to \mathrm{NaCl}\left(\mathrm{aq}\right)+{\mathrm{NH}}_3\left(g\right)+H_{2}O\left(\mathrm{aq}\right)$

For the given reaction, let's assume the total mass of $N{H}_{4}ClandNaOH$ taken was 50g. After complete reaction took place, the mass of $NaCland{H}_{2}O$ obtained was 40g.Then what is the mass of ${\mathrm{NH}}_3$ gas released?

• A. 20g
• B. 10g
• C. 50g
• D. 45g

Answer 1

The correct option is B 10g

According to law of conservation of mass, matter is neither created nor destroyed. Hence, the mass remains conserved after a change.
In other words, the mass of the products in a chemical reaction must equal the mass of the reactants.
In the reaction, ${\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{aq}\right)+\mathrm{NaOH}\left(\mathrm{aq}\right)\to \mathrm{NaCl}\left(\mathrm{aq}\right)+{\mathrm{NH}}_3\left(g\right)+H_{2}O\left(\mathrm{aq}\right)$

The mass of ${\mathrm{NH}}_4\mathrm{Cl}+\mathrm{NaOH}$ (Reactants) =50g
The mass of $\mathrm{NaCl}+H_2\mathrm{O\; (Products)}$=40g
Hence, the mass of ${\mathrm{NH}}_3$ =50g-40g=10g