In water weighing 120 g, 5 g of phosphorus oxide was dissolved by heating.
| December 23, 2020 | education
In water weighing 120 g, 5 g of phosphorus oxide was dissolved by heating. Calculate the mass fraction of phosphoric acid in the resulting solution.
Given: m (H2O) = 120g, m (P2O5) = 5g
Find: w (H3PO4)
Decision:
P2O5 + 3H2O = 2H3PO4
n (P2O5) = 5/142 = 0.035 mol
By ur-yu r-ii:
n (H3PO4) = 2 * n (P2O5) = 2 * 0.035 = 0.07 mol
m (H3PO4) = n * M = 0.07 * 98 = 6.86 g
m (total) = 120 + 5 = 125g
w (H3PO4) = 6.86 / 125 = 0.055 or 5.5%
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