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2012/2013 WAEC chemIsTrY

April 18, 2013

‘A’ is a solution of tetraoxosulphate(vi).
B is a solution coomtaining !.4g of potassiumb hydroxide per 25.0cm3.
(a.) Put A into burette and titrate with 20.0cm3 or 25.0cm3 portion into of B usingMethyl Orange as an indicator.
Record the volume of your pipette.
Tabulate your burette readings and calculate the average volume of acid used.
(b.) From your result and information provided. Calculate the
(i.) Concentration of B in mol/dm3
(ii.) Concentration of A inmol/dm3
(iii.) Number of Hydrogen ions in 1.0dm^2 of A.
The equation for the reaction is: H2SO4 2KOH –> k2SO4 2H2O.
{H=1, O=16, K=39}
Burrete reading(cm3)| Rough | 1st | 2nd | 3rd
Final(cm3) | 18.60 | 18.00| 20.30| 28.00
Initial(cm3) | 0.00 | 0.00| 2.30 | 10.00
Vol. Acid used(cm3)| 18.60 |18.00 | 18.00| 18.00
The average volume of acid used = 18.00 18.00 18.00/3 = 18.00cm3.
(bi.) Mass of KOH per dm3 of B = 39 16 1= 56.
Conc. of B = 5.6/56 = 0.01mol/dm3.
(bii.) The:::::::::::::ans loadin

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