Polyacrylamide is used in manufacturing soft contact lenses. It consist of 50.69% carbon, 19.71% nitrogen, 7.09% hydrogen, and 22.51% oxygen. Calculate the empirical formula for polyacrylamide.

Respuesta :

Answer: The empirical formula is [tex]C_3NH_5O[/tex].

Explanation:

If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given.

Mass of C = 50.69 g

Mass of N= 19.71 g

Mass of H = 7.09 g

Mass of O = 22.51 g

Step 1 : convert given masses into moles.

Moles of C = [tex]\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{50.69g}{12g/mole}=4.22moles[/tex]

Moles of N=[tex]\frac{\text{ given mass of N}}{\text{ molar mass of N}}= \frac{19.71g}{14g/mole}=1.41moles[/tex]

Moles of H=[tex]\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{7.09g}{1g/mole}=7.09moles[/tex]

Moles of O = [tex]\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{22.51g}{16g/mole}=1.41moles[/tex]

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C =[tex]\frac{4.22}{1.41}=3[/tex]

For N = [tex]\frac{1.41}{1.41}=1[/tex]

For H = [tex]\frac{7.09}{1.41}=5[/tex]

For O =[tex]\frac{1.41}{1.41}=1[/tex]

The ratio of C:N:H: O = 3:1:5:1

Hence the empirical formula is [tex]C_3NH_5O[/tex].