1. Tardigrade
  2. Question
  3. Chemistry
  4. The free energy change for the following reactions are given below. C2H2(g)+(5/2)O2(g) xrightarrow[]2CO2(g)+H2O(l); Δ G° =-1234 kJ C(s)+O2(g) xrightarrowCO2(g); Δ G° =- 394 kJ H2(g)+(1/2)O2(g) xrightarrowH2O(l); Δ G° =- 237 kJ What is the standard free energy change for the reaction? H2(g)+2C(s) xrightarrowC2H2(g)

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Q. The free energy change for the following reactions are given below. $ {{C}_{2}}{{H}_{2}}(g)+\frac{5}{2}{{O}_{2}}(g)\xrightarrow[{}]{{}}2C{{O}_{2}}(g)+{{H}_{2}}O(l); $ $ \Delta G{}^\circ =-1234\,kJ $ $ C(s)+{{O}_{2}}(g)\xrightarrow{{}}C{{O}_{2}}(g); $ $ \Delta G{}^\circ =-\,394\,kJ $ $ {{H}_{2}}(g)+\frac{1}{2}{{O}_{2}}(g)\xrightarrow{{}}{{H}_{2}}O(l); $ $ \Delta G{}^\circ =-\,237\,kJ $ What is the standard free energy change for the reaction? $ {{H}_{2}}(g)+2C(s)\xrightarrow{{}}{{C}_{2}}{{H}_{2}}(g) $

CMC MedicalCMC Medical 2014

Solution:

$ {{C}_{2}}{{H}_{2}}(g)+\frac{5}{2}{{O}_{2}}(g)\xrightarrow{{}}2C{{O}_{2}}(g)+{{H}_{2}}O\,(l); $ $ \Delta G{}^\circ =-1234\,kJ $ ?(i) $ C(s)+{{O}_{2}}(g)\xrightarrow{{}}C{{O}_{2}}(g); $ $ \Delta G{}^\circ =-\,394\,kJ $ ?(ii) $ {{H}_{2}}(g)+\frac{1}{2}{{O}_{2}}(g)\xrightarrow{{}}{{H}_{2}}O(l); $ $ \Delta G{}^\circ =-\,237\,kJ $ ?(iii) Eq. 2(ii) + (iii) - (i) $ 2C(s)+{{H}_{2}}(g)\xrightarrow{{}}{{C}_{2}}{{H}_{2}}(g) $ $ \Delta G{}^\circ =2(-394)+(-237)-(-1234) $ $ \Delta G{}^\circ =209\,kJ $