for the reaction at 298 K 2A+b ---->C

enthalpy=100 K/cal entropy= 0.050 kcal/k

assuming enthalpy and entropy to be constant over the temperature range, at what temperature will the reaction become spontaneous?

answer: T>2000K

Thomas, it wouldn't hurt to read over your posts before you push that submit button. No caps and no periods and typos to boot leave a post that's difficult to interpret. For this one I've guessed at half of the question; assuming I've guessed right you do the problem this way.

dG = dH - TdS
At the spontaneous stage, dG must be negative so substitute zero, the tipping point, for dG.
That gives you TdS = dH. Substitute the values for dS and dH and solve for T.

thanks

To determine at what temperature the reaction will become spontaneous, we can use the Gibbs Free Energy equation:

ΔG = ΔH - TΔS

Where ΔG is the change in Gibbs Free Energy, ΔH is the change in enthalpy, T is the temperature in Kelvin, and ΔS is the change in entropy.

For the reaction to become spontaneous, ΔG must be negative. Let's plug in the given values:

ΔH = 100 Kcal
ΔS = 0.050 Kcal/K

ΔG = 100 - T * 0.050

For the reaction to become spontaneous, ΔG < 0, so:

100 - T * 0.050 < 0

Simplifying the equation:

100 < T * 0.050

Dividing both sides of the inequality by 0.050:

2000 < T

Therefore, the reaction will become spontaneous at a temperature greater than 2000 K.