BACK TITRATION!! (ANOTHER QUESTION)

[leo93]

Hello, I encountered this question while doing my assignment which has really got me stumped. I would really appreciate any help I can get. Thanks.  

Here it is:
A given sample of sodium amide (NaNH₂) was warmed with excess aqueous ammonium chloride (NH4Cl)  to form ammonia and sodium chloride. The ammonia evolved was absorbed in 50.0cm³ of 0.200mol dm^-3 sulfuric acid. 25.0cm³ of the resulting solution required 14.00cm3 of 0.150mol dm^-3 potassium hydroxide for neutralisation. Calculate the mass of sodium amide used.

[kingchemist]

Find moles of KOH that react with excess H2SO4 using V in L x M. From the balanced equation, find the number of moles of H2SO4 that reacted with KOH. This number of moles of H2SO4 was in 25.0cm3, so double this answer to find the number of moles of H2SO4 that would have been in 50.0cm3. (= w moles)

Find the number of moles of H2SO4 originally present from 0.05 x 0.200. So subtract w moles from it to find the number of moles H2SO4 that must have neutralised the NH3. Find moles of NH3 and from the reaction of NaNH2 with NH4Cl find the number of moles of NaNH2, and then the mass