Question

The compound known as diethyl ether, commonly referred to as ether, contains carbon, hydrogen, and oxygen. A 1.626 g sample of ether was combusted in an oxygen rich environment to produce 3.862 g of CO2(g) and 1.976 g of H2O(g). Insert subscripts below to appropriately display the empirical formula of ether.

Answer 1

Empirical formula is the least coefficient formula, that is

CxHyOz

we must find x,y,z via gravimetry.

Typically we do this relating to moles of C,H,O

mol of CO2 = mass of CO2/MW of CO2 = (3.862)/(44) = 0.087772 mol of CO2

1 mol of CO2 = 1 mol of C ---> 0.087772 mol of CO2 = 0.087772mol of C

mol of H2O = mass of H2O/MW of H2O= (1.976)/(18) = 0.1097mol of H2O

1 mol of H2O= 2 mol of H ---> 0.1097mol of H2O= 0.1097*2 = 0.2194 mol of H

Now... mol of Oxygen:

Mass of O = Mass of sample - Mass of C - Mass of H

Mass of C = mol of C * MW of C = 0.087772 *12 = 1.0532 g

Mass of H = mol of H * MW of H = 0.2194*1= 0.2194 g

Mass of O = 1.626- 1.0532 -0.2194 = 0.3534 g of O

mol of O = mass of O / MW of O = (0.3534)/(16) = 0.0220875 mol of O

Ratios:

H:C =0.2194/0.087772 = 2.5 = 5/2

O:C =  0.0220875 /0.087772 = 0.25 = 1/4

H:O = 0.2194/0.0220875 = 9.99 = 10

then:

4 mol of C = 1 mol of O

10 mol of H = 1 mol of O

C4H10O

is the empiricla formula