CBSE (Science) Class 12CBSE

View all notifications

Out of C and CO, Which is a Better Reducing Agent at 673 K? - CBSE (Science) Class 12 - Chemistry

Create free account

      Forgot password?


Out of C and CO, which is a better reducing agent at 673 K?

Solution 1

At 673 K, the value of `triangleG_(CO,CO_2)` is less than that of `triangleG_(("C,CO"))` Therefore, CO can be oxidised more easily to CO2 than C to CO. Hence, CO is a better reducing ag ent than C at 673 K.

Solution 2

This can be explained thermodynamically, taking entropy and free energy changes into account.

`C(s) + O_2(g) -> CO_2(g)`

`2C(s) + O_2(g) -> 2CO (g)`

Case i: Volume of CO2 produced  = Volume of O2 used.

`:.triangleS` is very small and `triangleG` does not change with temperature.

:.Plot of `triangleG` Vs T is almost hrizontal

Case ii: Volume of CO produced = 2 x Volume of O2 used

`:.triangleS` is positive and hence `triangleG` beccomes increasingly negative as the temperature increases.

:.Plot of `triangle ""^@G` Vs T slopes downwards.


As can be seen from ΔG° Vs T plot (Ellingham diagram), lines for the reactions, C ——–> C02 and C ——–> CO cross at 983 K. Below 983 K, the reaction (a) is energetically more favourable but above 673 K, reaction (b) is favourable and preferred. Thus, below 673 K both C and CO can act as a reducing agent but since CO can be more easily oxidised to C02 than C to C02 , therefore, below 673 K, CO is more effective reducing agent than carbon

  Is there an error in this question or solution?


 NCERT Solution for Chemistry Textbook for Class 12 (2018 to Current)
Chapter 6: General Principles and Processes of Isolation of Elements
Q: 5 | Page no. 163

Video TutorialsVIEW ALL [1]

Solution Out of C and CO, Which is a Better Reducing Agent at 673 K? Concept: Extraction of Crude Metal from Concentrated Ore.
View in app×