A reaction at 1 bar is non-spontaneous at low temperature but becomes spontaneous at high temperature. Identify the correct statement about the reaction among the following :Both ΔH and ΔS are negativeBoth ΔH and ΔS are positiveΔH is positive while ΔS is negativeΔH is negative while ΔS is positive
Question
A reaction at 1 bar is non-spontaneous at low temperature but becomes spontaneous at high temperature. Identify the correct statement about the reaction among the following :Both ΔH and ΔS are negativeBoth ΔH and ΔS are positiveΔH is positive while ΔS is negativeΔH is negative while ΔS is positive
Solution
The correct statement about the reaction is: ΔH is positive while ΔS is positive.
Here's why:
The spontaneity of a reaction is determined by the Gibbs Free Energy change (ΔG), which is given by the equation ΔG = ΔH - TΔS, where ΔH is the change in enthalpy, T is the temperature, and ΔS is the change in entropy.
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If a reaction is non-spontaneous at low temperature but becomes spontaneous at high temperature, it means that the ΔG is positive at low temperature and becomes negative at high temperature.
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For ΔG to change from positive to negative as temperature increases, the TΔS term must be negative at low temperature and become positive at high temperature. This implies that ΔS is positive (since temperature is always positive).
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Since ΔG is positive at low temperature and ΔH = ΔG + TΔS, ΔH must also be positive. If ΔH were negative, then ΔG would be negative regardless of the value of TΔS, contradicting the fact that the reaction is non-spontaneous at low temperature.
Therefore, both ΔH and ΔS are positive for the reaction.
Similar Questions
A reaction at 1 bar is non-spontaneous at low temperature but becomes spontaneous at high temperature. Identify the correct statement about the reaction among the following
Which statement is true regarding a process for which ΔH is positive and ΔS is negative? Recall that, for any process: ΔG = ΔH - TΔSSelect answer from the options belowThe process is spontaneous at low temperatures only.The process is not spontaneous at any temperature.The process is spontaneous at all temperatures.The process is spontaneous at high temperatures only.
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