chemistry 1 help

Question

Phosphorus reacts with oxygen to form diphosphorus 

How many grams of  are formed when  of phosphorus reacts with excess oxygen? Show the unit analysis used for the calculation by placing the correct components into the unit-factor slots.

Answer 1

Here are the steps to solve this question:

1. Convert 7.65g of phosphorus to moles by dividing by the molar mass of phosphorus:

(7.65g P) x (1 mole P / 30.97g P) = 0.24701 mole P

2. Use the ratio of stoichiometric coefficients to convert moles of phosphorus to moles of diphosphorus pentoxide:

0.24701 mole P x (2 mole P₂O₅ / 4 mole P) = 0.123505 mole P₂O₅

3. Convert the moles of diphosphours pentoxide to grams by multiplying by the molar mass of P₂O₅:

0.123505 mole P₂O₅ x (141.94g P₂O₅ / 1 mole P₂O₅) = 17.5g P₂O₅

Here is the work all in one line:

(7.65g P) x (1 mole P / 30.97g P) x (2 mole P₂O₅ / 4 mole P) x (141.94g P₂O₅ / 1 mole P₂O₅)

=17.5g P₂O₅