What mass, in grams, of phosphorus trichloride will be produced from the 85.0 grams of phosphorus when it reacts with excess chlorine gas?

Question

_____ P4 + ____ Cl2 → _____ PCl3

Answer 1

To determine the mass of phosphorus trichloride produced when 85.0 grams of phosphorus react with excess chlorine gas, we need to balance the chemical equation first.

The balanced chemical equation for the reaction between phosphorus and chlorine gas to form phosphorus trichloride is:

P₄ + 6Cl₂ → 4PCl₃

According to this balanced equation, 1 mole of phosphorus (P₄) reacts with 6 moles of chlorine gas (Cl₂) to produce 4 moles of phosphorus trichloride (PCl₃).

To calculate the mass of phosphorus trichloride produced, we'll follow these steps:

1. Convert the given mass of phosphorus (85.0 grams) to moles using its molar mass. The molar mass of phosphorus (P₄) is approximately 123.9 grams/mole.

Moles of phosphorus = mass of phosphorus / molar mass of phosphorus

= 85.0 grams/123.9 grams/mole

≈ 0.686 moles

2. Based on the balanced equation, we know that the molar ratio between phosphorus (P₄) and phosphorus trichloride (PCl₃) is 1:4. Therefore, the number of moles of phosphorus trichloride produced will be:

Moles of phosphorus trichloride = Moles of phosphorus × (4 moles of PCl₃ / 1 mole of P₄)

= 0.686 moles × 4

≈ 2.744 moles

3. Finally, we can calculate the mass of phosphorus trichloride using its molar mass. The molar mass of phosphorus trichloride (PCl₃) is approximately 137.33 grams/mole.

Mass of phosphorus trichloride = Moles of PCl₃ × Molar mass of PCl₃

= 2.744 moles × 137.33 grams/mole

≈ 376.5 grams

Therefore, approximately 376.5 grams of phosphorus trichloride will be produced from the 85.0 grams of phosphorus when it reacts with excess chlorine gas.

Answer 2

1P₄ + 6Cl₂ → 4PCl₃

P₄ molecular mass = 4(30.97) = 123.88 g P

Molar mass of PCl₃ = 137.33 g/mol

123.88 g of P₄ gives 4(137.33 g/mol) = 549.32 g PCl₃

85 g of P₄ will give (549.32 × 85)/123.88 = 376.91 g PCl₃