Question

In the ellingham diagram there is. Sudden increase in the slope towards the positive side.But logically it should increase towards the negative side as entropy increases.COULD SOMEONE CLEAR MY DOUBTS, PLEASE,SIR/ MAMMA?

Answer 1

This is the sample of Ellingham diagram

In this diagram there is sharp bend in each metal oxide line and the metal oxide line started to move upwards(towards positive value of indicating that the metal oxide formation is not possible or metal oxide is unstable.
This is the easiest thing for extracting metal from metal oxide. For extraction of metal from its oxide the metal oxide should be unstable. Every metal oxide is likely unstable after the bend. So we can easily reduce the metal oxide after the bend.
Now we need to understand why the metal oxide is unstable after a certain point.
The value of free energy change can be found from

In this enthalpy change is always negative due to combustion.
The value of entropy change is negative means will become positive and will become positive.
The entropy of the reaction Metal +oxygen --> metal oxide is negative
This is because the gaseous oxygen is converted to solid metal oxide.
So entropy change in already negative. With the raise in the temperature the value of entropy change will be more and more negative because the rate of the reaction increases with increase in temperature. So the will become positive and metal oxide becomes unstable.