 Emperical Formula of a compound is the simpliest possible formula giving the ratio of atoms in a molecule of the compound. Example CH, HO, NH3, H2O e.t.c.

Molecular Formula The molecular is the formula which shows the actual number of atoms of the different elements present in one molecules of the compound. Example ( CH)n, (H2CO)n, (CH3)n e.t.c

Some given solution to some test questions

1. Determine the molecular formula of an alkane whose vapour density is 15 (H=1, C=12, R.M.M = 2, VD)

B. C3H6

C. C2H4

D. C2H6

Solution

emperical formular of alkane = (CH4)

(1 x 12 + 4 x 1)n = 2 x 15

16n = 30

Divide both sides by 16

16n/16 = 30/16

n = 1

2. A hydrocarbon X has a relative molar mass 56 and consists of 87.8% by mass of carbon and 12.2% hydrogen. Determine the empirical formula of X give its molecular formula

Solution

C                  H

87.8           12.2

12                1

Divide

7.32           12.2

Divide by the smallest ratio which is 12.2

1                   1   therefore Emperical formula of X is CH

Molecular formula

(12 + 1)n = 56

13n = 56

Divide both sides by 13

13n/13 = 56/13

N  = 4     therefore Molecular formular of X is C4H4

Do you know Emperical Formula Examples and Answer is among the simplest solving in chemistry?

3. A hydrocarbon containing 88.9% carbon has the empirical formula (H=1, C=12)

A. CH

B. CH2

C. C2H3

D. C2H5

Solution

C                   H

88.9             11.1

12                    1

Divide

7.4 1               11.1

Divide by the smallest ratio

1                         1        therefore the empirical formular is CH

Try this and solve

A compound contains 31.9% potassium, 28.93% chlorine and the rest oxygen. What is the chemical formular of the compound? ( K=39, CL=35.5, O=16)

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