Answer to Question #338819 in General Chemistry for Bertha

Question

A sample of ammonium sulphate was heated with 100.0 mL of 0.50mol/L aqueous sodium hydroxide. To ensure that all the ammonium sulphate reacted, an excess of sodium hydroxide was used. Heating was continued until all of the ammonia had been driven off as a gas. The unreacted sodium hydroxide remaining in the solution required 27.3 mL of 0.600mol/L hydrochloric acid for neutralization. Calculate the concentration of the ammonium salt.

Answer 1

Ammonium sulphate reacts with aqueous sodium hydroxide as shown by the equation below.

(NH4)2SO4 + 2NaOH ---> 2NH3 + Na2SO4 + 2H2O

A sample of ammonium sulphate was heated with 100 cm3 of 0.500 mol dm–3 aqueous*sodium hydroxide. To ensure that all the ammonium sulphate reacted, an excess of*sodium hydroxide was used.

Heating was continued until all of the ammonia had been driven off as a gas.

The unreacted sodium hydroxide remaining in the solution required 27.3 cm3 of

0.600 mol dm–3 hydrochloric acid for neutralisation.

(i) Calculate the original number of moles of NaOH in 100 cm3 of 0.500 mol dm–3 aqueous sodium hydroxide.0.05 moles

(ii) Calculate the number of moles of HCl in 27.3 cm3 of 0.600 mol dm–3 hydrochloric*acid.0.0164 moles

(iii) Deduce the number of moles of the unreacted NaOH neutralised by the hydrochloric*acid.

0.0164 moles