Chemistry- Volumetric analysis - Please Help!

Hello everyone,

If anyone out there is feeling extraordinarily generous, could you please please help with this problem! I'm absurdly hopeless with chemistry! Thank you. x

A 25.00mL sample of 'Cloudy Ammonia' was diluted to a volume of 250.00mL in a volumetric flask. A 25.00mL aliquot of the diluted solution was titrated with 0.200 M hydrochloric acid. To reach the end point, 26.75 mL of acid was required.
Calculate the concentration of ammonia in the cloudy ammonia.

NH3 + HCl > NH4Cl

NH3 + HCl -----------> NH4Cl

since reaction is taking place in 1 : 1 ratio ....

so at end point ...
no. of moles of HCl = no. of moles of NH3

and no.of moles of HCl = molarity X volume in litres = 0.2 X 0.02675 = 0.00535

so no.of moles of NH3 in 25 ml aliquot = 0.00535

so no.of moles of NH3 in 1 ml = 0.00535/25

no.of moles in 250 ml = 0.00535/25 X 250 = 0.0535

molarity = 0.0535/0.25 = 0.214 M

now since 25 ml sample was diluted to 250 ml so no.of moles of NH3 remains the same ...

so using M1V1 = M2V2 to calculate molarity in 25 ml sample ...

0.214 X 250 = M2 X 25

M2 = 2.14 M

so concentration of NH3 in original sample = 2.14 M

feel free to ask any question