With an excess of oxygen gas according to the following chemical equation. 4 P 502 > 2 P2Os What mass of P2O5 can be produced when a 172.1 g sample of phosphorus reacts

394.76g

Explanation:

Given parameters:

Mass of Phosphorus = 172.1g

Unknown:

Mass of P₂O₅ = ?

Solution:

We should work from the known specie to the unknown in this problem. The limiting reactant is the reactant in short supply and it determines the extent of the reaction. This is the given phosphorus.

Oxygen is in the excess.

The balanced reaction equation:

            4P + 5O₂   →   2P₂O₅

let us find the number of moles of phosphorus first,

 Number of moles of phosphorus =

Molar mass of phosphorus = 31g/mole

Number of moles =  = 5.55mole

   4 moles of phosphorus gives 2 moles of P₂O₅

 5.55 mole of P will produce   = 2.78moles

Mass of P₂O₅  = number of moles x molar mass

 Molar mass of P₂O₅  = (31 x 2)  +  (16 x 5)  = 142g/mole

Mass of P₂O₅  = 2.78moles x 142g/mole = 394.76g

the potential energy of the reactants is 200j.

from the energy diagram, the energy of the product formed is 350j; this means that, this reaction is an endothermic reaction, because it absorbs energy from its environment.