# Determine the mass of phosphorus, which is necessary for the reaction with oxygen, the mass of which = 320 g.

The phosphorus combustion reaction is described by the following chemical reaction equation:

2P + 5/2 O2 = P2O5;

When 2 moles of phosphorus are burned, 1 mole of its pentavalent oxide is formed. This is because the oxide molecule contains two phosphorus atoms. This requires 2.5 moles of oxygen.

Let’s calculate the chemical amount of a substance that is in 320 grams of oxygen.

M O2 = 32 grams / mol;

N O2 = 320/32 = 10 mol;

Let’s calculate the weight 10 x 5/2/2 = 12.5 mol of phosphorus.

M P = 31 grams / mol;

The weight of phosphorus will be:

m P = 31 x 12.5 = 387.5 grams;

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