Question

what,is,Erichal formula?

Answer 1

 empirical formula of a compound is the formula which expresses only the relative number of atoms of each element in the compound. Empirical formulas are sometimes called ‘the simplest formulas’ , but because they are obtained from experimental data, they are usually called empirical formulas, and are useful to:

1. Determine the molecular mass (or weight) of compounds whose molecular masses have not been known.

2. Determine the molecular masses of compounds whose molecular masses are variable, even though they have a definite percentage composition (i.e., for different compounds formed from the same elements).

To Determine Empirical Formula

To determine the empirical formula of a compound, we need to know:

1. The chemical composition of the compound - this is derived from experimental procedure, and can be expressed as percentage.

2. The relative atomic masses of the constituent elements.

Procedure: 1. From the chemical composition of the compound, and the relative atomic masses of the constituent elements given, convert the composition of each constituent element to number of moles.

2. Derive the mole ratio of the constituent elements.

3. Finally, express the mole ratio as the subscripts of the symbols of their respective element. The simplest formula obtained is the empirical formula.

Example: Analysis of carbon monoxide shows that it is 42.9% carbon and 57.1% oxygen. What is its empirical formula? (C=12, O=16) Solution: 1. Convert the percentage composition of each element to number of moles (consider each percentage as the mass).

Number of moles = mass (or % composition)