2. Solved Papers
  3. NEET

NEET AIPMT SOLVED PAPER 2002

  • question_answer
                    Heat of combustion \[\Delta {{H}^{o}}\] for C(s), \[{{H}_{2}}(g)\] and \[C{{H}_{4}}(g)\] are -94, -68 and -213 kcal/mol. Then \[\Delta {{H}^{o}}\] for \[C(s)+2{{H}_{2}}(g)\] \[\to \] \[C{{H}_{4}}(g)\] is:                                                                                                                                                                                                                                                                                                                                                                                                             

    A)                 -17 kcal  

    B)                 -111 kcal              

    C)                 -170 kcal 

    D)                 -85 kcal

    Correct Answer: A

    Solution :

                    For reaction,                 \[C(s)+2{{H}_{2}}(g)\xrightarrow[{}]{{}}C{{H}_{4}}(g),\,\Delta {{H}^{o}}=\,?\]                 \[\Delta {{H}^{o}}=-[(\Delta {{H}^{o}}\] of combustion of \[C+2\times \Delta H\] of combustion of \[{{H}_{2}})]\]                 \[C+{{O}_{2}}\xrightarrow{{}}C{{O}_{2}};\,\,\,\Delta H=-94\,\,kcal\]                                        ...(i)                 \[2{{H}_{2}}+{{O}_{2}}\to 2{{H}_{2}}O;\Delta H=-68\times 2\,kcal\]                                          ?(ii)                 \[C{{H}_{4}}+2{{O}_{2}}\to C{{O}_{2}}+2{{H}_{2}}O;\,\,\Delta H=-213\,kcal\]                       ?(iii)                 \[=-[(-213)-(-94+2\times -68)]\,\text{kcal/mol}\]                 \[=-[-213+230]=-17\,\,\text{kcal/mol}\]


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