[b0gummy]

How many moles of potassium are there in 40g of potassium arsenate?

What I have done so far

Molar Mass of Potassium Arsenate (K₃AsO₄) = 256.2165
Mass of Potassium Arsenate (K3AsO4) = 40g
Number of Moles of (K3AsO4) = 40g/256.2165 (=0.1561 mol)

Not entirely sure of how to get from 0.1561 mol to the number of moles of potassium in 40g of potassium arsenate. Help?

[b0gummy]

Nevermind, I have solved this problem. I used ratios to solve for it.

3 mol K/1 mol K3AsO4 = x mol K/0.1561 mol AsO4