Question

The equilibrium reaction below has the Kc = 0.254 at 25°C. If the temperature of the system at equilibrium is decreased to 0°C, how and for what reason will the equilibrium shift? Also show and explain how and why the Kc value will change.

Answer 1

Answer:

The equilibrium shifts towards reagents

Explanation:

Is known $Kc=\frac{[products]}{[reagents]}$  rised to the power of their number of moles in the balanced reaction. When you have a system at equilibrium with Kc < 1, it means [products] < [reagents] and the system needs energy to react, so if you decrease tempeture the equilibrium shifts towards reagents and less products will be created.

This efect can be discribed with Van´t Hoff equation: $ln(\frac{K1}{K2}) =-\frac{dH}{R} (\frac{1}{T1} -\frac{1}{T2} )$ where we can see that if we decrease temperature (this is T2<T1) in consecuense K2<K1 and reaction doesn´t happen.