A piece of dry ice (solid CO2) is placed inside a balloon, and the balloon is tied shut. Over time, the carbon dioxide sub- limes, causing the balloon to increase in volume. Give the sign of the enthalpy change and the sign of work for the sublima- tion of CO2.

Video transcript

Hi everyone for this problem. It reads an ice cube was accidentally left on a table over time. The ice cube melts determine the sign of the change in entropy for the melting of ice. So we want to know what is the sign of the change in entropy for the melting of ice. Okay, So in simple terms the entropy of a reaction is determined by the energy change that occurs during the reaction. So what we want to think of when we're thinking of entropy is heat being released or absorbed. Okay. So if a reaction is endo thermic that means heat is being absorbed and the sign for the change of entropy is going to be positive. Okay, on the other hand, if a reaction is eggs ah thermic that means heat is being released and the sign for the change in entropy is going to be negative. Okay, So we're right here that this is representing heat. Okay. And here we have ice melting. Okay, So if ice is melting, that means heat is being absorbed so that that ice can melt. All right. And so if heat is being absorbed then our sign for our change in entropy it's going to be positive. Alright. And so we're looking for a sign of an entropy greater than zero and out of our answer choices given that is reflected by answer choice. A So the sign of the change in entropy for the melting of ice is going to be greater than zero. It's going to be a positive sign because this represents an endo thermic reaction. That's it for this problem. I hope this was helpful.