Question

What is the empirical formula of a phosphoric acid that contains 0.3086 g of hydrogen, 3.161 g of phosphorus, and 6.531 g of oxygen?

Answer 1

`H_2` `P_4` `O_1`

Explanation:

In order to calculate the Empirical formula , we will assume that we have started with 10 g of the compound. On decomposition , we obtained 0.3086 g of Hydrogen , 3.161 g of Phosphorus, and 6.531 g of Oxygen.

*Step 1* Calculating the number of moles of different elements

`n_` `H`= mass of H/ molar mass of H

`n_` `H`= 0.3086 g / 1 g `mol^(-1)`

`n_` `H`= 0.3086 mol

`n_`P## = mass of P/ molar mass of P

`n_`P`= 3.161 g / 31 g`mol^(-1)#

`n_` `P`= 1.02 mole

`n_` `O` = mass of O / molar mass of O

`n_` `O`= 6.531 g / 32 g `mol^(-1)`

`n_` `O`= 0.2 mol

Calculating the Simple Ratio of the moles

H= 0.3806/ 0.2 =4 , P = 1.02 / 0.2 =5 , O= 0.2/0.2 =1

`H_2` `P_4` `O_1`