Polymers are large molecules composed of simple units repeated many times. thus, they often have relatively simple empirical formulas. calculate the empirical formulas of the following polymers: (a) lucite (plexiglas); 59.9% c, 8.06% h, 32.0% o (b) saran; 24.8% c, 2.0% h, 73.1% cl (c) polyethylene; 86% c, 14% h (d) polystyrene; 92.3% c, 7.7%

(a) C5H8O2

(b) C2H2Cl2

(c) CH2

(d) CH

Explanation:

We need to find the proportion of the atoms in whole numbers. Given the percentages we can calculate the number of moles and find their proportions.

Assume 100 g and given the atomic weights the moles are calculated.

(a) C = 59.9/ 12.01 = 4.98  ≈ 5.00

    H = 8.06/1.007 = 8.00

    O = 32/15.999  = 2.00

C5H8O2

(b) C= 24.8/12.01 = 2.06≈ 2.00

    H = 2.0/1.007 = 1.99 ≈ 2.00

   Cl = 73.1/ 35.453 = 2.06 ≈ 2.00

C2H2Cl2

(c) C = 86/12.01 = 7.16  

    H= 14/1.007 = 13.90

7.16:13.90 ≈ 1:2

CH2

(d) C = 92.30/12.01 = 7.68

    H = 7.7 / 1.007 =   7.65

7.68:7.65 ≈ 1:1

CH