Question

What is the molecular formula of a compound that contains 47.4% S and 52.6% Cl? The molecular mass of the compound as determined experimentally is 135 g/mol

Answer 1

Answer: The molecular formula of the compound is $S_2Cl_2$

Explanation:-

Step 1: Converting all these percentages into mass.

We take the total mass of the compound to be 100 grams, so, the percentages given for each element becomes its mass.

Mass of sulphur = $\frac{47.4}{100}\times 100g=47.4g$

Mass of chlorine= $\frac{52.6}{100}\times 100g=52.6g$

Molar mass of sulphur = 32 g/mole

Molar mass of chlorine = 35.5 g/mol

Step 2: Converting the given masses into their respective moles.

Moles of sulphur = $\frac{\text{Given mass of S}}{\text{Molar mass of S}}= \frac{47.4g}{32g/mole}=1.48moles$

Moles of chlorine = $\frac{\text{Given mass of Cl}}{\text{Molar mass of Cl}}= \frac{52.6g}{35.5g/mole}=1.48moles$

Step 3: Now, calculating mole ratio, we divide each number of moles by the smallest number of moles calculated.

For sulphur = $\frac{1.48}{1.48}=1$  

For chlorine = $\frac{1.48}{1.48}=1$

The ratio of S:Cl = 1:1

Hence the empirical formula is $S_1Cl_1$  

Empirical mass of $S_1Cl_1$ is = 32(1)+35.5 (1)=67.5 g

The equation used to calculate the valency is:

$n=\frac{\text{molecular mass}}{\text{empirical mass}}=\frac{135}{67.5}=2$

Step 4: To calculate the molecular formula=$n\times {\text {Equivalent Formula}}=2\times S_1Cl_1=S_2Cl_2$

Hence, the molecular formula of the compound is $S_2Cl_2$

Answer 2

Explanation:

Answer: The molecular formula of the compound is S_2Cl_2S

2

Cl

2

Explanation:-

Step 1: Converting all these percentages into mass.

We take the total mass of the compound to be 100 grams, so, the percentages given for each element becomes its mass.

Mass of sulphur = \frac{47.4}{100}\times 100g=47.4g

100

47.4

×100g=47.4g

Mass of chlorine= \frac{52.6}{100}\times 100g=52.6g

100

52.6

×100g=52.6g

Molar mass of sulphur = 32 g/mole

Molar mass of chlorine = 35.5 g/mol

Step 2: Converting the given masses into their respective moles.

Moles of sulphur = \frac{\text{Given mass of S}}{\text{Molar mass of S}}= \frac{47.4g}{32g/mole}=1.48moles

Molar mass of S

Given mass of S

=

32g/mole

47.4g

=1.48moles

Moles of chlorine = \frac{\text{Given mass of Cl}}{\text{Molar mass of Cl}}= \frac{52.6g}{35.5g/mole}=1.48moles

Molar mass of Cl

Given mass of Cl

=

35.5g/mole

52.6g

=1.48moles

Step 3: Now, calculating mole ratio, we divide each number of moles by the smallest number of moles calculated.

For sulphur = \frac{1.48}{1.48}=1

1.48

1.48

=1

For chlorine = \frac{1.48}{1.48}=1

1.48

1.48

=1

The ratio of S:Cl = 1:1

Hence the empirical formula is S_1Cl_1S

1

Cl

1

Empirical mass of S_1Cl_1S

1

Cl

1

is = 32(1)+35.5 (1)=67.5 g

The equation used to calculate the valency is:

n=\frac{\text{molecular mass}}{\text{empirical mass}}=\frac{135}{67.5}=2n=

empirical mass

molecular mass

=

67.5

135

=2

Step 4: To calculate the molecular formula=n\times {\text {Equivalent Formula}}=2\times S_1Cl_1=S_2Cl_2n×Equivalent Formula=2×S

1

Cl

1

=S

2

Cl

2

Hence, the molecular formula of the compound is S_2Cl_2S

2

Cl

2