An unknown hydrocarbon compound was analyzed for hydrogen by elemental analysis and results show that it contains 15.88 % H. What is the empirical formula

C4H9

Explanation:

If H = 15.88%

Then C = 100.00 – 15.88 = 84.12

Divide each % value by respective atomic mass

H = 15.88/1 = 15.88

C = 84.12/12 = 7.01

Divide through by smaller value

H = 15.88/7.01 = 2.26

C = 7.01/7.01 = 1

Remove fraction , multiply by 4

H = 9

C = 4

Empirical formula = C4H9

The hydrocarbon could be ( C4H9)2 = C8H18 = octane.

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml

the dissolution of polymer can be thermodynamically described in 2 steps.