Complete combustion of 1.5 g of fructose a sugar that contains carbon, hydrogen, and oxygen yields 2.2 g of carbon dioxide and .9 g of water. determine the empirical formula of fructose

Respuesta :

Answer:- [tex]CH_2O[/tex] .

Solution:- From given grams of carbon dioxide and water we could calculate their moles. using mole ratio, moles of C and H are calculated. These moles of C and H are converted to grams and then we subtract the sum of grams of C and H from given mass of compound to calculate the grams of oxygen. Grams of oxygen are converted to moles and then we find out the mole ratio of C, H and O that gives us empirical formula.

The calculations are as follows:

moles of carbon dioxide = [tex]2.2g(\frac{1mole}{44g})[/tex] = 0.05 mole

moles of water = [tex]0.9g(\frac{1mole}{18g})[/tex] = 0.05 mole

[tex]CO_2[/tex] has one C means the mole ratio of [tex]CO_2[/tex] to C is 1:1. So, moles of C would also be 0.05.

[tex]H_2O[/tex] has two H means the mole ratio of [tex]H_2O[/tex] to H is 1:2. So, moles of H would be 2 times the moles of [tex]H_2O[/tex] which is 0.10.

Let's convert moles of C and H to their grams as:

grams of C = [tex]0.05mole(\frac{12g}{1mole})[/tex] = 0.6 g

grams of H = [tex]0.10mole(\frac{1g}{1mole})[/tex] = 0.1g

grams of O = 1.5 - (0.6 + 0.1)

grams of O = 1.5 - 0.7 = 0.9 g

moles of O = [tex]0.9g(\frac{1mole}{16g})[/tex] = 0.056 moles

Let's calculate the mole ratio now:

[tex]C=\frac{0.05}{0.05}[/tex] = 1

[tex]H=\frac{0.1}{0.05}[/tex] = 2

[tex]O=\frac{0.056}{0.05}[/tex] = 1

From the mole ratio, the empirical formula of fructose is [tex]CH_2O[/tex] .