The crystalline hydrate Cd(NO₃)₂⋅4 H₂O(s) loses water when placed in a large, closed, dry vessel at room temperature: Cd(NO₃)₂⋅4 H₂O(s) → Cd(NO₃)₂(s) + 4  H₂O(g) This process is spontaneous and ΔH° is positive at room temperature. (b) If the hydrated compound is placed in a large, closed vessel that already contains a large amount of water vapor, does ΔS° change for this reaction at room temperature?

Video transcript

Welcome back everyone. We're told that when placed in a large closed dry container at room temp the crystalline hydrate, sodium sulfate hydrated in 10 moles of water spontaneously loses water by the below reaction where we form sodium sulfate as a participant eight with 10 moles of gaseous water at room temperature, it's change in entropy is positive. Does the change in entropy for this reaction at room temperature change if the hydrated compound is added to a large closed container that already has a large amount of water vapor present. So we want to recall that the change in entropy or standard entropy of our reaction is going to be our entropy change at standard temperature. Recall that that's 2 98 Kelvin for a reaction with all of its products and react ints in standard States. I'm sorry. We're missing a word here. So the standard entropy is going to be the entropy change. Just make this a bit neater entropy change at standard temperature. So what that's saying is that even if our reaction conditions change according to the prompt, like being placed in a large closed container with water vapor present, that's not going to change the disorder of our system or in this case our reaction is our system. So we should recognize that what will be changed is our change in free energy delta G. So this will change if our partial pressures of the water vapor in the container is changed. So for our final answer, we can confirm that the standard entropy for the reaction at room temperature does not change. Even if the hydrated compound is added to a large, closed container that already has a large amount of water vapor present. And this statement here is going to complete this example as our final answer. I hope that everything I went over was clear. If you have any questions, leave them down below and I'll see everyone in the next practice video.