Question

The composition by mass of a hydrocarbon is

10 %

hydrogen and

90 %

carbon. Deduce the empirical formula of this hydrocarbon. (

A_{r}

values:

C = 12.0, H = 1.0

).

Accepted Answer

The empirical formula of a chemical is a simple expression of the relative number of each type of atom in it, or the simplest whole number ratio of the elements present in one molecule.

Organic molecules generally contain different molecular and empirical formula.

We have given, percentage of hydrogen $A_{r}$ and percentage of carbon $= 90 %$

Divide the given percentage values by their $A_{r}$ values,

Carbon: $\frac{90}{12} = 7.5$

Hydrogen: $\frac{10}{1.0} = 10$

Finally, divide the above obtained values by the smallest obtained values.

Carbon: $\frac{7.5}{7.5} = 1.0$

Hydrogen: $\frac{10}{7.5} = 1.333$

If needed to multiply the numbers with one smallest number to get the smallest whole numbers.

Carbon: $1.0 \times 3 = 3$

Hydrogen: $1.333 \times 3 = 4$

Therefore, the empirical formula of the given compound is, $C_{3} H_{4}$ .

Lawrie Ryan and Roger Norris Solutions for Chapter: Atoms, Molecules and Stoichiometry, Exercise 13: Question

Lawrie Ryan Chemistry Solutions for Exercise - Lawrie Ryan and Roger Norris Solutions for Chapter: Atoms, Molecules and Stoichiometry, Exercise 13: Question

Questions from Lawrie Ryan and Roger Norris Solutions for Chapter: Atoms, Molecules and Stoichiometry, Exercise 13: Question with Hints & Solutions

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