Question 18Determine the formula of the organic compound if it's molecule contains 12 atoms of carbon. The percentage compositions of hydrogen and oxygen are 6.48 and 51.42 respectively.

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Accepted Answer

Element% compositionAt. wt.Relative no. of atomsSimplest ratioOxygen51.421651.4216\dfrac{51.42 }{16}1651.42​ = 3.213.213.21\dfrac{3.21}{3.21}3.213.21​ = 1Hydrogen6.4816.481\dfrac{6.48}{1}16.48​ = 6.486.483.21\dfrac{6.48}{3.21}3.216.48​ = 2Carbon42.11242.112\dfrac{42.1}{12}1242.1​ = 3.503.503.21\dfrac{3.50}{3.21}3.213.50​ = 1Simplest ratio of whole numbers = O : H : C = 1 : 2 : 1Hence, empirical formula is CH2OSince the compound has 12 atoms of carbon, so the formula is C12H24O12.

Element	% composition	At. wt.	Relative no. of atoms	Simplest ratio
Oxygen	51.42	16	$\dfrac{51.42 }{16}$ = 3.21	$\dfrac{3.21}{3.21}$ = 1
Hydrogen	6.48	1	$\dfrac{6.48}{1}$ = 6.48	$\dfrac{6.48}{3.21}$ = 2
Carbon	42.1	12	$\dfrac{42.1}{12}$ = 3.50	$\dfrac{3.50}{3.21}$ = 1

Mole Concept and Stoichiometry — Question 18

Question 18