Predict the sign of the entropy change in the system for each of the following processes. (a) A solid sublimes. (b) A liquid freezes. (c) AgI precipitates from a solution containing Ag+ and I- ions. (d) Gaseous CO2 bubbles out of a carbonated beverage.

Video transcript

Hello everyone in this video. We want to find out the sign of the change of entropy for each of the given processes. So we have A B, C and D. So let's go ahead and recall what entropy even is. So entropy is the degree of chaos or disorder of a system and it's dependent on one of them is going to be the phase. So the gas phase has the highest entropy followed by the liquid. And then the solid face with the lowest entropy. So the reason for this is because the gas particles have a higher mobility. So it can kind of violence around each other and against the walls of the container, meaning that there's going to be more randomness and disorder. Next up it's depending on it's going to be the complexity. So for complexity it means that the more elements in the compound we have a higher entropy. So let's come let's take an example let's say we have N. 03. This has four atoms or elements Which has a high entropy compared to let's say n. 0. 2 which only has three atoms. Then the third thing is dependent on is going to be the mass. So the greater the mass, the greater the entropy. So let's take into an example let's say xenon in its gaseous state. This has a greater mass than helium gas. Alright so for the first one here we have the F. E. Three plus and O. H minus ions that form our solid here. So we have two ions that form one solid product. This will give us a delta S value, that's negative. Give me a move which is put on top, then delta S value equal to minus. So we can see here that the entropy has decreased because we went from two ions into just one solid. Now for B we have methane gas that's released from solid waste. This is going to be we can see that the solid waste is going into methane gas and this is going to be of course an increase in entropy. So we'll have a positive value. Delta us equals positive for a gas that condenses. This condensation is going from our gas state into a liquid state. And of course we just said that the gas has a higher entropy. So this is going to be a negative delta S. And lastly for statement D. Here says a liquid evaporates some vibration is when liquid goes through gas. Already know that gas has a higher entropy. So my delta S. Here is going to be positive. So our answer is then, is that for a we have the delta S equal into negative for statement D. We have the delta S being positive. First statement see we have the delta S being negative and statement D. We have the delta S being positive. So this right here is going to be my final answers for this problem