1. Cl2(g) -> 2Cl(g)
2. H2(g) at 5.0 atm -> H2(g) at 1.0 atm
3. sublimation of solid CO2
4. 2H2(g) + O2(g) -> 2H20(g)
5. PCl5(g) <-> PCl3(g) + Cl2(g)
A. The change in entropy will be positive.
B. The change in entropy will be zero.
C. The change in entropy will be negative.
D. The change in entropy can either be positive or negative.
E. The change in entropy cannot be determined from the information given.
[I'm horribly lost in this chapter...]
i've looked in my book for entropy and i figured out that 3 was A, and 5 was E. I'm still stuck on the others.
Think in terms of order. Solid CO2, for example, has some kind of a crystalline arrangement while the gas does not, so the entropy change should be negative since it will be going from a more ordered arrangement to a less ordered arrangement.
1. A
2. A
3. A
4. C
5. B
To determine the changes in entropy for the given reactions, let's consider the concept of entropy and how it relates to the order and disorder of a system.
Entropy (S) is a measure of the randomness or disorder in a system. When a system becomes more disordered or random, the entropy increases, and when a system becomes more ordered, the entropy decreases.
Let's go through each reaction and analyze the changes in entropy:
1. Cl2(g) -> 2Cl(g)
In this reaction, one molecule of chlorine gas (Cl2) is breaking apart into two separate chlorine atoms (Cl). The reactant molecules are more ordered than the product molecules, as the reactant has a higher degree of chemical bonding. Therefore, the reaction will lead to an increase in entropy, which means the change in entropy will be positive.
So for reaction 1, the change in entropy will be A. The change in entropy will be positive.
2. H2(g) at 5.0 atm -> H2(g) at 1.0 atm
This reaction involves a change in pressure. Going from higher pressure to lower pressure, the gas molecules will have more freedom to move and disperse, resulting in an increase in disorder and entropy. Therefore, the change in entropy will be positive.
So for reaction 2, the change in entropy will be A. The change in entropy will be positive.
3. Sublimation of solid CO2
Sublimation refers to the process where a solid directly converts into a gas without going through the liquid phase. When solid CO2 (dry ice) sublimes, it transforms from a highly ordered, crystalline structure to a more disordered and diffuse gas phase. The disorder increases, and hence, the entropy also increases. Therefore, the change in entropy will be positive.
So for reaction 3, the change in entropy will be A. The change in entropy will be positive.
4. 2H2(g) + O2(g) -> 2H2O(g)
This reaction involves the formation of water vapor by combining hydrogen gas and oxygen gas. Here, the number of gas molecules increases from three (2H2 + O2) to four (2H2O), resulting in an increase in randomness and disorder. As a result, the entropy increases, and the change in entropy will be positive.
So for reaction 4, the change in entropy will be A. The change in entropy will be positive.
5. PCl5(g) <-> PCl3(g) + Cl2(g)
This reaction is in equilibrium, and we cannot determine the change in entropy based on the given information. Entropy change during an equilibrium process depends on factors such as temperature and the relative probabilities of reactant and product states. Therefore, the change in entropy cannot be determined from the information given, which is option E.
To recap:
1. A. The change in entropy will be positive.
2. A. The change in entropy will be positive.
3. A. The change in entropy will be positive.
4. A. The change in entropy will be positive.
5. E. The change in entropy cannot be determined from the information given.
Understanding the concept of entropy and analyzing the degree of order or disorder in a system allows us to determine the changes in entropy for different reactions.