Decide whether each of the following statements is true or...

Decide whether each of the following statements is true or false. If false, rewrite it to make it true. (a) The entropy of a substance increases on going from the liquid to the vapor state at any temperature. (b) An exothermic reaction will always be spontaneous. (c) Reactions with a positive $\Delta_{r} H^{\circ}$ and a positive $\Delta_{\mathrm{r}} S^{\circ}$ can never be product-favored. (d) If $\Delta_{r} G^{\circ}$ for a reaction is negative, the reaction will have an equilibrium constant greater than 1.

Decide whether each of the following statements is true or false. If false, rewrite it to make it true.
(a) The entropy of a substance increases on going from the liquid to the vapor state at any temperature.
(b) An exothermic reaction will always be spontaneous.
(c) Reactions with a positive $\Delta_{r} H^{\circ}$ and a positive $\Delta_{\mathrm{r}} S^{\circ}$ can never be product-favored.
(d) If $\Delta_{r} G^{\circ}$ for a reaction is negative, the reaction will have an equilibrium constant greater than 1.

Key Concepts

Equilibrium Constant

The equilibrium constant (K) is related to the standard Gibbs free energy change of the reaction. For reactions with a negative ?G°, the equilibrium constant will be greater than one, indicating that products are favored at equilibrium. This link between ?G° and K is essential in predicting reaction outcomes.

Entropy Change

Entropy is a measure of the disorder or randomness in a system and is a crucial concept when considering phase transitions. Generally, when a substance changes from a more ordered state (like a liquid) to a less ordered state (like a vapor), the entropy increases, but this trend has temperature and pressure dependent nuances.

Enthalpy Change

Enthalpy change refers to the heat absorbed or released during a reaction at constant pressure. While exothermic reactions release heat and may contribute to reaction spontaneity, the trajectory of a reaction is not solely dictated by whether it is exothermic or endothermic; the interplay with entropy is key.

Gibbs Free Energy

Gibbs free energy combines the effects of enthalpy and entropy changes into a single value, ?G. It indicates the spontaneity of a reaction; a negative ?G means the reaction is thermodynamically favorable. The balance between ?H and ?S, along with temperature, determines whether a reaction occurs spontaneously.

Transcript

00:01 So for this question, it's asked us to determine if these following statements are true or false.

00:11 So the first statement, we're told that entropy increases as you go from a liquid state to a gaseous state or a vapor state.

00:23 This statement is entropy, right, is describing the state of disorder or chaos.

00:34 So when we move from a liquid state to a gaseous state, right, those atoms in a gaseous state are in much more chaos and much more disorder, right? because they can expand to fill a container, whereas liquid is more confined.

00:55 So no matter what temperature, whenever you change from either a solid to a liquid or a liquid, to a gas, that entropy is always going to increase.

01:10 So this statement is true.

01:12 For the next statement, b, it says that an exothermic reaction is always spontaneous.

01:24 And this is also true, correct? that's just the definition of an exothermic reaction.

01:30 An exothermic reaction means that the products are favored.

01:35 So if the products are favored, then that that reaction, action is always going to be spontaneous, meaning it's going to move in the four direction and be favored towards the products.

01:48 Exothermic reaction means that you don't need any added energy to make that reaction occur.

01:54 If the reaction occurs, there is actually a release in energy.

02:02 And so, because you don't need energy to make that reaction occur, it's always going to be product favored.

02:08 So the statement that exothermic reaction is always spontaneous is true.

02:14 Next for statement c, we're asked if reactions that have a positive enthalpy and a positive entropy are never product favored.

02:27 So this statement is going to be false.

02:30 And here's why...