DO YOU WANT 10 YAHOO POINTS & CAN U DO TITRATION CALCULATiONS?

Question

A solution of a metal carbonate, M2CO3 was prepared by dissolving 7.46g of the anhydrous solid in water to give 1000 cm3 of solution. 25 cm3 of this solution reacted with 27 cm3 of 0.100M hydrochoric acid. Calculate the relative formula mass of M2CO3 and hence the relative atomic mass of the metal M.

Answer 1

If tha atomic mass of M is A, then the molecular weight is MW=2*A+60

The concentration of the M2CO3 solution is C=mole/V and since mole=mass/MW, C=mass/(MW*V)

Then you do a titration for which we assume complete reaction and not reaching only the first end-point, so the reaction is

M2CO3 + 2HCl -> 2MCl + CO2 + H2O

Therefore 2*mole M2CO3=mole HCl =>
2*C1*V1= C2*V2=>
2*V1*mass/(MW*V) = C2*V2 =>
MW= 2*V1*mass/(C2*V2*V)=
=2*0.025*7.46/(0.1*0.027*1)
=138

and MW=2*A+60=138=> 2A=78 => A=39

So M, is potassium (K)

Answer 2

according to what you said the answers are 138 , 39 respectively. of course the metal is Potasium " K" and the compound is K2CO3.

Answer 3

i DO want ten points.