0.25 g of an organic compound containing carbon, hydrogen and oxygen was analysed by the combustion method. The increase in mass of calcium chloride tube and the potash bulbs at the end of the operation was found to be 0.15 mg and 0.1837 g respectively. Calculate the percentage composition of the compound.

Solution

(i) Percentage of carbon.
Increase in mass of potash bulbs = 0.1837 g
i.e. mass of CO₂ formed = 0.1837 g
$therefore space space Percentage space of space straight C space space space space space space equals space 12 over 44 cross times fraction numerator Mass space of space CO subscript 2 over denominator Mass space of space compound end fraction cross times 100 space space space space space space equals space 12 over 44 cross times fraction numerator 0.1837 space cross times space 100 over denominator 0.25 end fraction space equals space 20.04$

(ii) Percentage of hydrogen.
Increase in mass of calcium chloride = 0.15 g
i.e. mass of water formed = 0.15 g
$therefore space space space Percentage space of space hydrogen space space space space space space space space space space space space space space equals space 2 over 18 cross times fraction numerator Mass space of space straight H subscript 2 straight O over denominator Mass space of space compound end fraction cross times 100 space space space space space space space space space space space space space space space equals space 2 over 18 cross times fraction numerator 0.15 space cross times space 100 over denominator 0.25 end fraction space equals space 6.66$

(iii) Percentage of oxygen.
Percentage of oxygen
= 100 - (Percentage of C + Percentage of H)
= 100 - (20.04 + 6.66) = 73.30

Some More Questions From Organic Chemistry – Some Basic Principles and Techniques Chapter

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Organic Chemistry – Some Basic Principles And Techniques

Some More Questions From Organic Chemistry – Some Basic Principles and Techniques Chapter

What type of hybridisation is involved in: (i) Planar (ii) Linear molecules?

What does IUPAC stand for?

What system of nomenclature is accepted universally?

What are isomers?

How many chain isomers are possible for pentane?

Which characteristic is common to different isomers of a compound?

Name three alkanes which do not show chain isomerism.

Name the types of structural isomerism shown by alkanes.

Name the four main types of structural isomerism.

Write the three possible open chains of five carbon atoms

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