[tiny101]

Hello, I've hit a road block with this question and I'm hoping someone can point me in the right direction.

The problem states that a 5.30-g sample containing only Mn2(SO4)3(s) and Al2(SO4)3(s) is dissolved in aqueous solution. The metal ions are precipitated as hydroxides, which are pyrolyzed in air to produce 1.85 g of a mixture of Mn2O3(s) and Al2O3(s). What was the percent Mn in the original sample?

I've designated x = mass of Mn2O3 and with that, I found that the moles of Mn would be = 2x/157.87

What is the next step? Or, am I completely mistaken?
Thx in advance 

[Borek]

Assume x moles of manganese sulfate and y moles of aluminum sulfate. Write equations for mass of sulfates and mass of oxides (hint: use molar masses and stoichiometry). Two equations, two unknowns, simple algebra.

[tiny101]

How would I write the equation for the mass of oxides? Should I write up the chemical equations (as in how they react with one another) to figure out the moles of the oxides, then write the equation?

Thanks again.

[Borek]

Assume there are x moles of Mn.

What will be mass of the Mn₂(SO₄)₃?

What will be mass of the Mn₂O₃?

These are very basic moles/mass conversions.

Now think - does the number of moles of Mx (x) change during the reactions, or not?