Question

What is the molecular formula of a compound given the molar mass of the compound is 62.18 g/mol and the empirical formula is c2h7?

Answer 1

The molecular formula is C4H14.

Step-by-step explanation:

The molar mass of a compound is the mass of one mole of that compound. The empirical formula represents the simplest whole-number ratio of atoms in a compound. To find the molecular formula, you need to find the multiple of the empirical formula that gives the molar mass.

In this case, the molar mass is given as 62.18 g/mol and the empirical formula is C2H7. The empirical formula mass of C2H7 is 29.11 g/mol (2×(12.01 g/mol) + 7×(1.01 g/mol)). To find the multiple, divide the molar mass by the empirical formula mass: 62.18 g/mol / 29.11 g/mol = 2.1352.

Since we can't have a fractional number of molecules, round the multiple to the nearest whole number. Therefore, the molecular formula of this compound is C4H14.

Answer 2

To get the molecular formula we use the individual atomic masses of the atoms making the molecule. Hence, to get the factor by which the empirical formula is multiplied, we divide molar mass by the total of the mass of the atoms making the empirical formula.
(C2H7) the mass of one carbon atoms is 12 so two atoms add up to 24. The mass of one hydrogen atom is 1 a.m.u thus 7 atoms give a total of 7 a.m.u. The sum of the two types of atoms is 24+7= 31
Molar mass=62.18
62.18/31=2.0
Hence, (C2H7) 2=C4H14