Thanks for your help.

Question

I have a problem to solve et don't know how to do part of it.

We have a solution of XNO3 (X = monovalent cation
We add a solution of K2SO4.
We obtain an insoluble sulfate which precipitate and KNO3

The precipitate = 3.900 g

The analyses shows that the precipitate contains 10,263% of S and that its molar mass = 312 g/mol

1) Find the equation

My equation is: 2XNO3 + K2SO4 = X2SO4 + 2KNO3

2) What's the mass of SO4?

3) What's the molar mass of Cation X?

my answer is: (312-32-16X4)/2 =108

I can't find the answer of the second question

Thank you for your help

Answer 1

find moles of S.
molesS=totalmass*.10263/32=.39/32= .0122
molesO=4*.0122=.0488
massO=.0488*16=.788 grams
massX=(3.9-.788-.39)=2.72
molesX=2*.0122=.0244
molemassX=mass/moles=2.72/.0244=111.5
check that, most of it was in my head.

Answer 2

Thank you. It is all right. I've understood.
Have a nice day