Question

Finding chemical formulae from a mole ratio An unknown compound has the following chemical formula C,H Measurements also show that a certain sample of the unknown compound contains 6.2 mol of hydrogen Write the complete chemical formula for the unknown compound. and 2.08 mol of carbon Da Exp nation Think IP Asset Tag KIP port # 201-817-1090

Answer 1

We first have to determine the ration of carbon and hydrogen in the compound. Given the molecular formula is C₂H_x. So the ration of number of atoms of carbon to number of atoms of hydrogen is 2:x.

Now, we have given information that a certain amount of compound contains 6.2 mol hydrogen and 2.08 mol carbon. So we find out the ratio of moles of carbon to hydrogen which is 2.08:6.2 = 2.08/6.2 = 0.3355.

The amount of hydrogen and carbon has come from the compound only. So the ratio of number of atoms must be equal to the ratio of number of moles. So we can write

2/x = 0.3355

So x = 2/0.3355 = 5.96

It is given that x is a whole number. So we take the round up value of x. So x= 6.

Therefore the chemical formula of the compound is C₂H₆.