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?