[Rutherford]

When 10.3g of a metal A is melted with KHSO₄, 33.4g of anhydrous alum of that metal is made (SO₂ is obtained, too). Determine the metal A and write the balanced equation for the reaction.

If I assume that the metal is monovalent, then from x moles of A, x moles of KASO₄ will be obtained.
x=10.3/M and x=33.4/(M+96+39)=33.4/(M+135), therefore
10.3/M=33.4/(M+135)
M=60.2g/mol which doesn't fit to any metal, if I assume that the metal was divalent, M=120.4g/mol, again nothing, and for trivalent there is no good answer. Where am I wrong?

[Borek]

First of all - alum means metal is trivalent.

[Rutherford]

Thanks for reminding me. That way I got the correct answer, I am only unsure why when I used the equivalent mass I didn't get the right answer?