2. Questions Bank
  3. JEE Main & Advanced
  4. Chemistry
  5. Some Basic Concepts of Chemistry / रसायन की कुछ मूलभूत अवधारणाएँ

JEE Main & Advanced Chemistry Some Basic Concepts of Chemistry / रसायन की कुछ मूलभूत अवधारणाएँ Question Bank Chemical stoichiometry

  • question_answer
    A solution containing \[N{{a}_{2}}C{{O}_{3}}\] and NaOH requires 300 ml of 0.1 N HCl using phenolpthalein as an indicator. Methyl orange is then added to the above titrated solution when a further 25 ml of 0.2 N HCl is required. The amount of NaOH present in solution is \[(NaOH=40,\,N{{a}_{2}}C{{O}_{3}}=106)\] [CPMT 1992]

    A)                 0.6 g      

    B)                 1.0 g

    C)                 1.5 g      

    D)                 2.0 g

    Correct Answer: B

    Solution :

               (I) Phenopthalein indicate partial neutralisation of \[N{{a}_{2}}C{{O}_{3}}\to NaHC{{O}_{3}}\]                    Meq. of \[N{{a}_{2}}C{{O}_{3}}\]+ Meq. of  NaOH = Meq. of HCl                    \[\frac{W}{E}\times 1000+\frac{W}{E}\times 1000=NV\]                    (Suppose \[N{{a}_{2}}C{{O}_{3}}=a\,gm\], NaOH = b gm)                    \[\frac{a}{106}\times 1000+\frac{b}{40}\times 1000=300\times 0.1\].....(1)                    (II) Methyl orange indicate complete neutralisation                    HCl   HCl                    \[{{N}_{1}}{{V}_{1}}={{N}_{2}}{{V}_{2}}\], \[25\times 0.2=0.1\]\[\times \]\[{{V}_{2}}\,\text{so}\,{{V}_{\text{2}}}=50ml\]excess                    \[\therefore \]  \[\frac{a}{53}\times 1000+\frac{b}{40}\times 1000=350\times 0.1\].....(2)                                 From (1) and (2)  b =1gm.


You need to login to perform this action.
You will be redirected in 3 sec spinner