Respuesta :
Number of moles is defined as the ratio of given mass in g to the molar mass.
First, convert the given mass of carbon dioxide in mg to g:
1 mg = 0.001 g
17.61 mg = 0.01761 g
Number of moles of carbon dioxide = [tex]\frac{0.01761 g}{44.01 g/mol}[/tex]
= [tex]0.0004001 mol[/tex]
Mass of carbon = number of moles of carbon dioxide \times molar mass of carbon
= [tex]0.0004001 mol\times 12.011 g/mol[/tex]
= [tex]0.004806 g[/tex]
Number of moles of water= [tex]\frac{0.00481 g}{18 g/mol}[/tex]
= [tex]2.672\times 10^{-4}[/tex]
Since, water contains two hydrogen atoms. Thus,
Moles of hydrogen = [tex]2\times 2.672\times 10^{-4}[/tex]
= [tex]5.34\times 10^{-4}[/tex]
Mass of hydrogen = [tex]5.34\times 10^{-4}\times \times 1.008 g/mol[/tex]
= [tex]5.34\times 10^{-4} g [/tex]
Mass of oxygen = [tex]0.001175-(5.38\times 10^{-4}g+0.004806 g)[/tex]
= [tex]0.006405 g[/tex]
Number of moles of oxygen = [tex]\frac{0.006405 g}{15.999 g/mol}[/tex]
= [tex]0.000400[/tex]
Now,
[tex]C_{0.0004001} H_{0.000534} O_{0.000400}[/tex]
Divide the smallest number to get the whole number,
[tex]C_{\frac{0.0004001}{0.000400}} H_{\frac{0.000534}{0.000400}} O_{\frac{0.000400}{0.000400}}[/tex]
we get,
[tex]C_{1} H_{1.33} O_{1}[/tex]
Now, multiply all the subscript by 3 to get the whole number,
[tex]C_{3} H_{4} O_{3}[/tex] (empirical fomula)
Molar mass of the compound =[tex]3\times 12.011 g/mol+4\times 1.008 g/mol+3\times 15.999 g/mol[/tex]
= [tex]88.062 g/mol[/tex]
Divide given molar mass of the compound with the molar mass of the compound.
=[tex]\frac{176.1 g/mol}{88.062 g/mol}[/tex]
= [tex]1.999\simeq 2[/tex]
Thus, multiply the subscripts of empirical formula by 2 to get the molecular formula, we get:
[tex]C_{6}H_{8}O_{6}[/tex]
Hence, empirical formula is [tex]C_{3}H_{4}O_{3}[/tex] and molecular formula is [tex]C_{6}H_{8}O_{6}[/tex]
