11th Class Chemistry Organic Chemistry: Some Basic Principles & Techniques / कार्बनिक रसायन : कुछ मूलभूत सिद्धांत एवं तकन

  • question_answer 58)
    A sample of 0.50 g of an organic compound was treated according to Kjeldahls method. The ammonia evolved was absorbed in 50 mL of 0.5 M\[{{H}_{2}}S{{O}_{4}}\]. The residual acid required 60 mL of 0.5 M solution of\[NaOH\] for neutralisation. Find the percentage composition of nitrogen in the compound.

    Answer:

    Mass of the organic compound = 0.50 g Unused acid required = 60 mL of 0.5 M \[NaOH\] =30 ML of 1 M\[NaOH\] Volume of acid taken = 50 mL of 0.5 M \[{{H}_{2}}S{{O}_{4}}\] = 25 mL of 1 M \[{{H}_{2}}S{{O}_{4}}\] Now 1 mole of \[{{H}_{2}}S{{O}_{4}}\] neutralizes 2 moles of \[NaOH\] \[({{H}_{2}}S{{O}_{4}}+2NaOH\to N{{a}_{2}}S{{O}_{4}}+2{{H}_{2}}O)\] So, 30 mL of 1M \[NaOH\] = 15 mL of 1 M \[{{H}_{2}}S{{O}_{4}}\] So, volume of acid used by ammonia = 25 - 15 = 10 mL % of nitrogen = \[\frac{1.4\times {{N}_{1}}\times V}{W}=\frac{1.4\times 1\times 2\times 10}{0.5}\] = 56%  


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