![]() We're decreasing the dispersal of energy, and therefore delta S of the surroundings will be less then zero. ![]() An endothermic reaction when Delta H is greater than zero, or a positive value, shows we're absorbing energy from surroundings. We're dispersing that energy and so the Delta S of the surroundings is increasing. For endothermic reactions, so that will be a reaction where Delta H is less than zero, so a negative value, we see that the delta S of surroundings is greater than zero because an exothermic reaction is releasing energy. So, how do we find the delta S of the surroundings? We know it's dependent on temperature but we have to find the actual value of it. This means that at a lower temperature we have a higher impact, so looking at the relative values of the Delta S of the system versus the delta S of the surroundings the temperature will determine how much the Delta S of the surroundings will impact the value of the delta S of the system and therefore how it will impact the delta S of the universe. As the temperature decreases or drops the amount of entropy for a given amount of energy dispersed increases. As the temperature increases the amount of entropy for a given amount of energy dispersed decreases, therefore, something at a higher temperature has a lower impact and will not change the Delta S of the system as much. So remembered that energy tells us about the dispersal of energy, and the qualitative value tells us that entropy is a measure of energy dispersed per unit of temperature. It's the Delta S of the surroundings that depends on the temperature because that's going to determine how that energy is dispersed. For both of these we see that the Delta S of the system is the same, but we see that the Delta S of the surroundings is different and therefore the Delta S of the universe ends up being different. At higher temperatures it is a non spontaneous process, so what we have to look at is where's the energy going? We're dispersing energy so we have to look at the temperature of the surroundings to see which one is going to favor the spontaneous process. Looking at the freezing of water we know that at lower temperatures this happen spontaneously. Let's take an example where this process is not always spontaneous. It's the balance and the signs of these numbers that determine whether or not a process is spontaneous. ![]() when we look at the values at the delta S of the system and delta S of the surroundings we see that we can have both values as positive numbers, both fighters negative numbers, or have one value that's positive and one value that's negative. ![]() ![]() What we have to look at are the individual components to determine whether or not a process is spontaneous. these are not necessarily negatives of one another. #ENTROPY OF THE UNIVERSE PLUS#We also know that the change in entropy of the universe is equal to the change in entropy of the system plus the change in entropy of the surroundings. When we look at entropy of the universe we know that we must have a positive value in order to have a spontaneous process. Our objective is to understand how temperature affects the entropy of the surroundings, and in turn, how that affects the entropy of the universe. In this module we're going to look at how we find the entropy of the universe to determine whether or not a process is spontaneous. ![]()
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