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# Edecxel Hodder Education Exam-practise help

1. First time using the site, I need a hand understanding the method behind one of the questions at the end of section eleven Their website has the answer, but nothing on how to actually work it out - any light shed would be very appreciated.
"A solution of ammonia in water was shaken with an equal volume of an organic solvent until the substance reached equilibrium with the ammonia distributed between the two solvents. In a series of titrations, 10cm3 of the aqueous layer was neutralised by 17.0cm3 of HCL of concentration 0.50 moldm-3 - What was the concentration of ammonia in the aqueous layer at equilibrium?"
2. u can work out moles of HCL, therefore using a balanced equation u could work out moles of aqueos layer, then u could use C=M/V TO work out conc, or is that wrong, i do aqa chem btw
3. (Original post by bshackers)
u can work out moles of HCL, therefore using a balanced equation u could work out moles of aqueos layer, then u could use C=M/V TO work out conc, or is that wrong, i do aqa chem btw
Not too sure, there are no equations within the question itself so I'm not too sure where to even start.The answer says to just: (17/10)*0.5 but i couldn't tell you why
4. Yep i got it now

Moles of HCL= CV = 17/1000 times 0.5 = 0.0085
Assuming 1 to 1 ratio moles of aq = 0.0085
conc = m/v
0.0085 / (10/1000) = 0.85 ( which is same as the answer )

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