What mass of phosphorus is contained in a 15.5*g mass of P_2O_5?

1 Answer
anor277
Mar 10, 2017

"Mass of phosphorus"~=7*g.

Explanation:

We need (i) to assess the molar quantity of P_4O_10 (which of course is the same as P_2O_5, and which formula we can use without loss of generality).

"Moles of" P_4O_10 = (15.5*g)/(283.89*g*mol^-1)=0.0546*mol.

Now in one mole of P_4O_10, CLEARLY there are 4 moles of phosphorus. So (ii) we need to multiply the given molar quantity by 4xx30.9737*g*mol^-1, where 30.9737*g*mol^-1 is the atomic mass of phosphorus.

"Mass of phosphorus" = 0.0546*molxx4xx30.9737*g*mol^-1

~=7*g.

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