A mixture of 196.1 g of P and 202.6 g of O2 reacts completely to form P4O6 and P4O10- Find the masses of P4O6 and P4O10 that are formed by the reaction.

Answer 1

First, write the equation for the reaction and balance it

8 P + 8 O₂→ P₄O₆ + P₄O₁₀

To use the balanced equation, we must convert grams to moles using the molar mass of each: P and O₂

We'll divide by the molar masses (shown on the periodic table)

196.1 g P × 1 mol/30.974 g = 6.331 mols P

202.6 g O₂ × 1 mol/31.9988 g = 6.331 mols O₂

Since we have an equal number of each reactant and the number of moles for each is the same (8) in the balanced equation, in relation to the product, we can use either one to move on with the calculation.

We'll select P to move on. The rest of the calculation requires us to compare the moles of P to each product and then find the mass.

Starting with P₄O₆ we compare its moles to P in the balanced equation.

8 mols P: 1 mol P₄O₆

So we divide by 8 to get the number of mols of P₄O₆

6.331 mols P × 1 mol P₄O₆/8 mols P = 0.7914 mols P₄O₆

Convert those mols to mass, using the molar mass of P₄O₆ ---- 219.88 g/mol

Multiply mols by the molar mass ------ 0.7914 mols P₄O₆ × 219.88 g/mol = 174.0 g P₄O₆

The same applies to the other product: (equation says 8 mols P: 1 mol P₄O₁₀)

6.331 mols P × 1 mol P₄O₁₀/8 mols P = 0.7914 mols P₄O₁₀

The molar mass of this product is different (it has 10, not 6 oxygens) ------- 0.7914 mols P₄O₁₀ × 283.89 g/mol = 224.7 g P₄O₁₀