Elemental analysis of caffeine yields the following results: 49.49% c, 5.15% h, 28.87% n, and the remainder is o. what is the molecular formula of caffeine?

The answer to your question is C₄H₅N₂O

Explanation:

Process

1.- Calculate the percent of oxygen in the sample

    Percent of oxygen = 100 - 49.49 - 5.15 - 28.87

    Percent of oxygen = 16.49 %

2.- Write the percents as grams

C = 49.49 g

H = 5.15 g

N = 28.87 g

O = 16.47 g

3.- Convert the grams to moles

C          12 g 1 mol

          49.49 g  x

             x = (49.49 x 1) 12

             x = 4.12 moles

H        1 g   1 mol

         5.15 g  x

            x = (5.15 x 1)/ 1

            x = 5.15 moles

N          14 g   1 mol

            28.87 g  x

              x = (28.87 x 1) / 14

              x = 2 mol

O           16 g 1 mol

              16.49 g x

               x = (16.49 x 1) / 16

               x = 1.03 moles

4.- Divide by the lowest number of moles

C     4.12 /  1.03 = 4

H      5.15 / 1.03 = 5

N       2 / 1.03 = 1.9 ≈ 2

O      1.03 / 1.03 = 1

5.- Write the empirical formula

                                 C₄H₅N₂O

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

yes

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