12/29/2023 0 Comments Decrease in entropy![]() Stars are hotter than planets, for example, which are warmer than icy asteroids, which are warmer still than the vacuum of the space between them. Although it may have seemed disorderly, and therefore, superficially entropic, in fact, there was enormous potential energy available to do work-all the future energy in the universe.Īs the universe matured, temperature differences arose, which created more opportunity for work. Gravity played a vital role in the young universe. ![]() In the early, energetic universe, all matter and energy were easily interchangeable and identical in nature. Heat Death of the Universe: An Overdose of Entropy A decrease in the number of moles of gas corresponds to a decrease in entropy (S < 0). I understand mathematically why entropy decreases because the denominator (Temperature) in the entropy equation deltaSq/t increases and since the number you. Entropy can decrease somewhere, provided it increases somewhere else by at least as much. Some processes result in a decrease in the entropy of a system S < 0 S < 0: A gas molecule dissolved in a liquid is much more confined by neighboring molecules than when its in the gaseous state. It says that the total entropy of the universe can never decrease. So you see, the second law doesn't say that entropy can never decrease anywhere. This heat represents an increase in entropy which more than makes up for the decrease in entropy due to the rearrangement of the air molecules, and the second law holds, as always. And a byproduct of this process is, once again, heat. But just as with the refrigerator, this process can't take place on its own. When you do this, you're moving air molecules from a region where air is relatively sparse, to a container where the air is much denser. At some point you've probably used a small hand pump to inflate a bicycle tire or a volleyball. The second law of thermodynamics is safe! But the increase in entropy due to the additional heat produced in the refrigeration process will make up the difference (with room to spare for any realistic fridge). So if we only consider the heat pumped into your kitchen from the food storage area of your refrigerator, there's a decrease in the entropy of the kitchen/refrigerator combination. And more heat means an increase in entropy. (Hey, I'm a theorist, okay?) But the byproduct of this is that more heat is produced and pumped into your kitchen. Whatever it is that refrigerators do when you plug them in. This energy is used to drive a motor inside your fridge, and pump some fluid around or something. When you plug it in, energy is delivered from some power plant to your refrigerator. ![]() Your refrigerator doesn't work unless you plug it in. Well if this process happened by itself, the second law of thermodynamics would be violated. So here, when heat flows from cold to warm, it must decrease! Another apparent violation of the second law of thermodynamics. Solids have the lowest amount of entropy, since atoms are tightly packed together and have little movement. If entropy is decreasing, the reactants are reacting to produce products which have less disorder. Entropy increases when heat flows from warm to cold. The reaction is going from 3 moles of gas to 2 moles of gas. From the refrigerator (cold) to your kitchen (warm). The basic function of a refrigerator is to take heat out of its interior, and transfer it out the back into your kitchen (or wherever your refrigerator is). Let's consider the refrigerator that's making your ice. (Entropy increases when heat flows from a warm substance to a cold substance.)īut it gets more interesting. As for the total amount of entropy, it increases. So the entropy of your freezer increases, while the entropy of the water decreases. When heat is added to something, its entropy increases. Heat flows from the water (which is warmer) to the rest of the freezer. You put water at, say 40 degrees (Fahrenheit) into your 20 degree freezer. Entropy can decrease in some things, provided it increases in others. (I've made amazingly convincing arguments for this by now!) We've said as an example, that the entropy of water increases when it melts, and decreases when it freezes. We've said that the entropy of the universe never decreases.
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