In Part A, you found the number of moles of product (3.80 mol P2O5) formed from the given amount of phosphorus and excess oxygen. In Part B, you found the number of moles of product (3.40 mol P2O5) formed from the given amount of oxygen and excess phosphorus. Now, determine the number of moles of P2O5 is produced from the given amounts of phosphorus and oxygen. Express your answer to three significant figures and include the appropriate units.

3.40 moles of P2O5 will be produced

Explanation:

Step 1: Data given

Number of moles P2O5 = 3.80 moles

Number of moles P2O5 = 3.40 moles

Step 2: The balanced equation

4P + 5O2 → 2PO5

Step 3: Calculate moles

For 4 moles P we need 5 moles O2 to produce 2 moles P2O5

in part A: the limiting reactant is P and we form 3.80 moles P2O5

For 3.80 moles P2O5 have 2*3.80 moles = 7.60 moles P

In part B, the limiting reactant is oxygen

For 3.40 moles P2O4 we need 2.5 * 3.40 = 8.50 moles O2

Step 4: Calculate the limiting reactant

For 4 moles P we need 5 moles O2 to produce 2 moles P2O5

Oxygen is the limting reactant. It will completely be consumed. (8.50 moles O2). Phosphorus is in excess. There will react 4/5 * 8.50 = 6.70 moles P

There will remain 7.60 - 6.80 = 0.80 moles P

Step 5: Calculate moles P2O5

For 4 moles P we need 5 moles O2 to produce 2 moles P2O5

For 8.50 moles O2 we'll have 2/5 * 8.50 = 3.40 moles P2O5

3.40 moles of P2O5 will be produced