A 15.0-kg block of ice at 0.0°C melts to liquid water at 0.0°C inside a large room at 20.0°C. Treat the ice and the room as an isolated system, and assume that the room is large enough for its temperature change to be ignored. (a) Is the melting of the ice reversible or irreversible? Explain, using simple physical reasoning without resorting to any equations.

Video transcript

welcome back everybody. We take an ice cream cake out of the freezer and when we do it has a temperature of negative 18 degrees Celsius. Now, after a time of 30 minutes, it actually cools down to a temperature of degrees Celsius. And we are tasked with two things. One determining whether or not the state is reversible or irreversible. And we are also tasked with finding what is the sign on the change in entropy as the ice cream cake melts. So let's go ahead and tackle part one here real quick. I want to point now say that we take our our little bowl of ice cream right? And we put it out on the counter and then it melts down and fills up the bowl. There's no way that heat will flow out of the ice cream into the warm kitchen to once again make this ice cream frozen again. That's just not possible. Meaning that this process is going to be irreversible. Alright, moving on to part two here, what is the signage on the change in entropy? Well, for an irreversible process this increases the total entropy of the system, meaning that the change in entropy is going to be greater than zero or positive. So we found that our process was irreversible and we found that our change in entropy was greater than zero. Which leads us to a final answer of C. Thank you all so much for watching. Hope this video helped. We will see you all in the next one