Question

Calculate the percent composition by mass of the following compounds that are important starting materials for synthetic polymers: a. C3H4O2 (acrylic acid, from which acrylic plastics are made) b. C4H6O2 (methyl acrylate, from which Plexiglas is made) c. C3H3N (acrylonitrile, from which Orlon is made)

Answer 1

Answer:

C₃H₄O₂ → 50% C; 5.5 % H; 44.5% O

C₄H₆O₂ → 56 % of C; 7 % of H; 37% of O

C₃H₃N → 68 % of C; 6 % of H; 26 % of N

Explanation:

We determine the molar mass of each compound:

C₃H₄O₂ → 72 g/mol

In 1 mol of acrylic acid (72 g), we have:

3 moles of C → 12 g/mol . 3 mol = 36 g of C

4 moles of H → 1 g/mol . 4 mol = 4 g of H

2 moles of O → 16g/mol . 2 mol = 32 g of O

Then in 100 g of salt, we may have:

100 . 36 / 72 = 50 % of C

4 . 100 / 72 = 5.5 % of H

32 . 100 / 72 = 44.5 % of O

C₄H₆O₂ → 86 g/mol

In 1 mol of methyl acrylate (86 g), we have:

4 moles of C → 12 g/mol . 4 mol = 48 g of C

6 moles of H → 1 g/mol . 6 mol = 6 g of H

2 moles of O → 16g/mol . 2 mol = 32 g of O

Then in 100 g of salt, we may have:

100 . 48 / 86 = 56 % of C

6 . 100 / 86 = 7 % of H

32 . 100 / 86 = 37 % of O

C₃H₃N → 53 g/mol

In 1 mol of acrylonitrile (53 g), we have:

3 moles of C → 12 g/mol . 3 mol = 36 g of C

3 moles of H → 1 g/mol . 3 mol = 3 g of H

1 mol of N → 14g/mol . 1 mol = 14 g of N

Then in 100 g of salt, we may have:

100 . 36 / 53 = 68 % of C

3 . 100 / 53 = 6 % of H

14 . 100 / 53 = 26 % of N