Question

A compound contains 4.07% hydrogen, 24.27% carbon and 71.65% chlorine by mass. Its molar mass is 98.96g. what is its empirical formula? Atomic masses of hydrogen, carbon and chlorine are 1.008, 12.000 and 35.453 u respectively​

Answer 1

Answer:

C2Cl2H4

Step-by-step explanation:

If it's 98.96g total and 4.07% is hydrogen then 0.0407x98.96= mass of hydrogen = 4.023g of hydrogen.

4.023/1.008= moles of hydrogen =3.996 mol

98.96x0.2427= mass of carbon= 24.02g

24.02/12.000 = moles of carbon= 2.001 mol

0.7165x98.96= mass of chlorine= 70.9g

70.9/35.453= moles of chlorine= 2 mol

With rounding there is 4 mol of hydrogen 2 mol of carbon and 2 mol of chlorine.

This means the compound must have this ratio between the atoms (2:1:1).

The compound would be first assumed to be the lowest common number for the ratio which is C1Cl1H2 however as can be seen by drawing a Lewis structure this doesn't work.

The next number which satisfies the ratio must then be tried which is 4 hydrogens, 2 carbons and 2 chlorines or C2Cl2H4 this does work with a Lewis structure with every atom able to have a full valence shell.

Therefore this is the compound.

Hope this helps.