There is 4 g of a mixture of P2O5 and K3PO4, in which the mass fraction of phosphorus is 21.88%. Determine the mass

There is 4 g of a mixture of P2O5 and K3PO4, in which the mass fraction of phosphorus is 21.88%. Determine the mass of substances in the original mixture.

Suppose that in 4 g of the mixture there was “x” mol – P2O5, “y” mol – K3PO4. Then: n (P in P2O5) = 2x. n (P in K3PO4) = y. Let’s find the mass of phosphorus: m (P) = 21.88 * 4/100 = 0.88 g. N (P) = m / M = 0.88 / 31 = 0.028 mol. We compose the system of equations: 142x + 212y = 4.2x + y = 0.028. Solving: x = 0.00686. y = 0.01428. m (P2O5) = 0.00686 * 142 = 1 g. m (K3PO4) = 0.01428 * 212 = 3 g.