NEET Chemistry Thermodynamics / रासायनिक उष्मागतिकी Question Bank Self Evaluation Test - Thermodynamics

  • question_answer
    When 1 mole of oxalic acid is treated with excess of \[NaOH\] in dilute aqueous solution, \[106kJ\] of heat is liberated. Predict the enthalpy of ionisation of the acid

    A) \[4.3\text{ }kJ\text{ }mo{{l}^{-1}}\]                

    B) \[-4.3\,kJ\,mo{{l}^{-1}}\]

    C) \[8.6\text{ }kJ\,mo{{l}^{-1}}\]             

    D) \[-8.6\,kJ\,mo{{l}^{-1}}\]

    Correct Answer: C

    Solution :

    [c] \[{{H}^{+}}(aq)+O{{H}^{-}}(aq)\rightleftharpoons {{H}_{2}}O(l);\] \[\Delta H=-57.3kJ\]               .... (i) \[{{H}_{2}}{{C}_{2}}{{O}_{4}}+2O{{H}^{-}}\rightleftharpoons {{C}_{2}}O_{_{4}}^{-}+2{{H}_{2}}O;\Delta H=-106kJ\].... (ii) For the second reaction the value should have been \[2\times \left( -57.3 \right)=-114.6kJ\] The difference \[\left( 114.6-106 \right)=8.6\text{ }kJ\,mo{{l}^{-1}}\] is used to effect of the ionisation of oxalic acid.


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