Question

How many grams of Cl are in 38.8 g of each sample of chlorofluorocarbons (CFCs)?

1. CF2Cl2

2. CFCl3

3. C2F3Cl3

4. CF3Cl

Answer 1

1)

Molar mass of CF2Cl2,

MM = 1*MM(C) + 2*MM(F) + 2*MM(Cl)

= 1*12.01 + 2*19.0 + 2*35.45

= 120.91 g/mol

mass(CF2Cl2)= 38.8 g

use:

number of mol of CF2Cl2,

n = mass of CF2Cl2/molar mass of CF2Cl2

=(38.8 g)/(1.209*10^2 g/mol)

= 0.3209 mol

This is number of moles of CF2Cl2

one mole of CF2Cl2 contains 2 mole of Cl

use:

number of moles of Cl = 2 * number of moles of CF2Cl2

= 2 * 0.3209

= 0.6418

Molar mass of Cl = 35.45 g/mol

use:

mass of Cl,

m = number of mol * molar mass

= 0.6418 mol * 35.45 g/mol

= 22.75 g

Answer: 22.8 g

2)

Molar mass of CFCl3,

MM = 1*MM(C) + 1*MM(F) + 3*MM(Cl)

= 1*12.01 + 1*19.0 + 3*35.45

= 137.36 g/mol

mass(CFCl3)= 38.8 g

use:

number of mol of CFCl3,

n = mass of CFCl3/molar mass of CFCl3

=(38.8 g)/(1.374*10^2 g/mol)

= 0.2825 mol

This is number of moles of CFCl3

one mole of CFCl3 contains 3 mole of Cl

use:

number of moles of Cl = 3 * number of moles of CFCl3

= 3 * 0.2825

= 0.8474

Molar mass of Cl = 35.45 g/mol

use:

mass of Cl,

m = number of mol * molar mass

= 0.8474 mol * 35.45 g/mol

= 30.04 g

Answer: 30.0 g

3)

Molar mass of C2F3Cl3,

MM = 2*MM(C) + 3*MM(F) + 3*MM(Cl)

= 2*12.01 + 3*19.0 + 3*35.45

= 187.37 g/mol

mass(C2F3Cl3)= 38.8 g

use:

number of mol of C2F3Cl3,

n = mass of C2F3Cl3/molar mass of C2F3Cl3

=(38.8 g)/(1.874*10^2 g/mol)

= 0.2071 mol

This is number of moles of C2F3Cl3

one mole of C2F3Cl3 contains 3 mole of Cl

use:

number of moles of Cl = 3 * number of moles of C2F3Cl3

= 3 * 0.2071

= 0.6212

Molar mass of Cl = 35.45 g/mol

use:

mass of Cl,

m = number of mol * molar mass

= 0.6212 mol * 35.45 g/mol

= 22.02 g

Answer: 22.0 g

4)

Molar mass of CF3ClS,

MM = 1*MM(C) + 3*MM(F) + 1*MM(Cl) + 1*MM(S)

= 1*12.01 + 3*19.0 + 1*35.45 + 1*32.07

= 136.53 g/mol

mass(CF3ClS)= 38.8 g

use:

number of mol of CF3ClS,

n = mass of CF3ClS/molar mass of CF3ClS

=(38.8 g)/(1.365*10^2 g/mol)

= 0.2842 mol

This is number of moles of CF3ClS

one mole of CF3ClS contains 1 moles of Cl

use:

number of moles of Cl = 1 * number of moles of CF3ClS

= 1 * 0.2842

= 0.2842

Molar mass of Cl = 35.45 g/mol

use:

mass of Cl,

m = number of mol * molar mass

= 0.2842 mol * 35.45 g/mol

= 10.07 g

Answer: 10.1 g