Tell whether the free-energy changes, ΔG, for the processes listed in Problem 9.127 are likely to be positive, negative, or zero.

Video transcript

Hey everyone we're told for the given process is below identify whether the free energy changes DELTA G. For each will be positive, negative or zero first. Let's go ahead and recall some facts we know about delta G. So if our delta G is less than zero, or if our delta G is negative, this means our reaction is spontaneous. Now if our delta G is equal to zero, this means our reaction is at equilibrium. Now if our delta G is greater than zero, or if our delta G is positive, this means our reaction is non spontaneous. Using this information, let's go ahead and answer our question. So for a we have water flowing down from a rocky slope, so this is due to gravity. So this means we have a spontaneous reaction and because we have a spontaneous reaction, this means that our delta G is going to be equal to negative. Now let's go ahead and look at B for B. We have when ethanol liquid evaporates at 64.7°C, which is its normal boiling point. So as we've learned at its boiling point, we are at equal Librium. And because we're at equilibrium, this means our delta G is equal to zero. Now let's go ahead and look at C for C. We have ice melts into liquid water at 0°C As we know our melting point is 0°C, which is also our freezing point. So at our melting point we are also at equilibrium. So this means our delta G is equal to zero and these are going to be our final answers. Now, I hope this made sense and let us know if you have any questions.