Write the equation for the reaction of combustion of phosphorus, aluminum.

| May 22, 2021 | education

Write the equation for the reaction of combustion of phosphorus, aluminum. Calculate the mass fraction of oxygen in the reaction product.

1) Phosphorus (V) oxide is formed:
4P + 5O2 => 2P2O5;
2) Calculate the relative molecular weight of P2O5:
Mr (P2O5) = Ar (P) * N (P) + Ar (O) * N (O) = 31 * 2 + 16 * 5 = 142;
3) Calculate the mass fraction of O in P2O5:
ω (O in P2O5) = N (O in P2O5) * Ar (O) * 100% / Mr (P2O5) = 5 * 16 * 100% / 142 = 56.34%;
4) Aluminum oxide is formed:
4Al + 3O2 => 2Al2O3;
5) Calculate the relative molecular weight of Al2O3:
Mr (Al2O3) = Ar (Al) * N (Al) + Ar (O) * N (O) = 27 * 2 + 16 * 3 = 102;
6) Calculate the mass fraction of O in Al2O3:
ω (O in Al2O3) = N (O in Al2O3) * Ar (O) * 100% / Mr (Al2O3) = 3 * 16 * 100% / 102 = 47.06%.



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