6. Chemical Equilibrium
Chemical Thermodynamics: Gibbs Free Energy
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Recall that a spontaneous reaction is one that happens naturally without the need of outside energy. Whereas a non spontaneous reaction is one that doesn't normally occur unless some outside forces in play. If we take a look here, we have to figure out which of the following is an example of a non spontaneous process. Alright. First, we have ice melting at room temperature. Now we know that as long as the temperature is above 0 degrees Celsius, which room temperature is, ice will naturally melt. Because this happens in real world scenarios, it is a spontaneous process. Next, sodium metal reacting violently with water. This one, probably not as well known. Just remember here that when it comes to group 1a and 2a metals, because of the low number of valence electrons they have, they will violently react with water in order to lose an electron to become more like a noble gas. Here, this is true. Because it happens naturally in the real world, it's a spontaneous process. Here, rusting of iron at room temperature. So old cars, when it rains, they can rust. This is a natural process that happens every day. And because of that, it's a spontaneous process. A ball rolling downhill. So a ball can naturally roll down a hill using its momentum as well as gravity to to push itself down that hill. We can see that this happens, just by imagining it. You could take a ball and throw it down a hill. You'll see it roll down naturally, so it's spontaneous process. Now even if you weren't able to determine if the initial 4 were spontaneous or not, you should know that e is a non spontaneous process. Here, it says water freezing at room temperature. Room temperature is much too warm for water to freeze. Water has to be at 0 degrees Celsius or lower in order to begin to freeze. We should know that this makes no sense. It's not a natural occurrence. It could only happen if we invested some outside energy. For example, we have a refrigerator where we put an ice tray in. The refrigerator is in a room at room temperature but inside the refrigerator, it's much lower than that. Therefore, water could freeze. The last option here, we're gonna say, does not naturally occur. Water will not freeze at room temperature under natural conditions. Therefore, it is the process that is non spontaneous. Also remember, as we set up above, spontaneous reactions move in the forward direction. They never move in the in the reverse direction because if it's spontaneous, it's gonna move forward. It is nonreversible or irreversible. Non spontaneous processes are not spontaneous in the forward direction, so they tend to move in the reverse direction to become spontaneous. So non spontaneous processes are reversible.
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