CHM 116 CH19

True or false. Endothermic reactions can be spontaneous.

True, endothermic reactions can be spontaneous

Why can endothermic reactions be spontaneous? (criteria for spontaneity) -Endothermic reactions can be spontaneous due to ____. This is because in entropy matter tends to go a more _____ state that disperses energy. -Entropy change is ___ than 0

-Endothermic reactions can be spontaneous due to entropy. This is because in entropy matter tends to go to a more random state that disperses energy -Entropy change is less than 0

What are the criteria for spontaneity? -Matter tends to go to a state of _____ energy --Which means that Enthalpy change is _____ than 0

-Matter tends to go to a state of lower energy --This means that Enthalpy change is less than 0

What is the accepted reference point from which all entropy states are compared? ____ K is the accepted reference point from which all entropy states are compared

0 K is the accepted reference point from which all entropy states are compared.

What happens to the energy of the system when a decrease in enthalpy occurs ? A decrease in enthalpy (exothermic process) _____ the energy of the system

A decrease in enthalpy (exothermic process) lowers the energy of the system.

What makes a process (or chemical reaction) spontaneous? A process is considered spontaneous when the combined effect of ______ and entropy lead to an overall ____ energy of the system

A process is considered spontaneous when the combined effect of enthalpy or entropy lead to an overall lower energy of the system.

A process that is spontaneous in one direction is NOT _______ in the _____ direction (under those conditions)

A process that is spontaneous in one direction is NOT spontaneous in the reverse direction (under those conditions)

How do you describe a reaction that is not spontaneous in either direction? It is a _____ reaction that can move

A reaction that is not spontaneous in either direction is at equilibrium. It is a reversible reaction that can move back and forth along the same path

A spontaneous reaction: - implies nothing about the _____ of the reaction or the ____ of the reaction - always moves a chemical reaction mixture _____ equilibrium

A spontaneous reaction: - implies nothing about the rate of the reaction or the extent of the reaction - always moves a chemical reaction mixture toward equilibrium -is an irreversible process

What happens when there is an increase in entropy? An increase in entropy results in a state with _____ possible energy states/ arrangements, which ___ the energy of the system

An increase in entropy results in a state with more possible energy states/ arrangements, which lowers the energy of the system

What is the change in enthalpy? Change in enthalpy is the measure of the heat ____ or ______ when at constant pressure

Change in enthalpy is the measure of the heat released or absorbed when at constant pressure

Delta G is the_____ amount of energy available to do on the surroundings

Delta G is the maximum amount of energy available to do work on the surroundings

What is delta G used for? Delta G is used to decide if a chemical reaction is ____

Delta G is used to decide if a chemical reaction is spontaneous.

Entropy decreases with _____ temperature because motion ____

Entropy decreases with decreasing temperature because motion decreases

Entropy increases as freedom of ______ increases

Entropy increases as freedom of motion increases.

Entropy increases with increasing _______ ______

Entropy increases with increasing molecular complexity.

What kind of function is entropy? Entropy is a _____ function.

Entropy is a state function.

If a reaction is nonspontaneous, it means that it does NOT occur unless _____ is added from an external source

If a reaction is nonspontaneous, it means that it does NOT occur unless energy is added from an external source.

What does it mean if a reaction is spontaneous? If a reaction occurs spontaneously, it means that it occurs ____ external intervention.

If a reaction occurs spontaneously, it means that it occurs without external intervention.

"An increase in entropy is statistically favored." What is meant by this? In general, it means that the number of microstates available to a system increases with an increase in ____, increase in _______, or an increase in the number of ________.

In general, it means that the number of microstates available to a system increases with an increase in volume, increase in temperature, or an increase in the number of molecules.

Molecular motion ______ with temperature, so entropy ______ with temperature

Molecular motion increases with temperature, so entropy increases with temperature.

Rotational molecular motion is the ____ of a molecule around an axis

Rotational molecular motion is the spinning of a molecule around an axis.

What is the change in entropy? The change in entropy is a measure of randomness or ______ of energy among molecular motion

The change in entropy is the measure of the randomness or distribution of energy among molecular motions

What is the difference between a perfect crystal and an imperfect crystal? The difference is that for a perfect crystal entropy is ____ to zero, and the entropy of an imperfect crystal is ____ than zero

The difference is that for a perfect crystal entropy is equal to zero, and the entropy of an imperfect crystal is less than zero.

What does the first law of thermodynamics apply to?

The first law of thermodynamics applies to enthalpy.

How does Boltzmann's Equation and Microstates relate to entropy? The greater the number of available microstates, the ______ the entropy

The greater the number of available microstates, the greater the entropy

What does the third law allow us to do? The third law of thermodynamics allows us to determine _____ entropies for substances at any temperature

The third law of thermodynamics allows us to determine absolute entropies for substances at any temperature.

What is the third law of thermodynamics? The third law of thermodynamics is the entropy of a pure,____ perfect _____ substance at absolute zero (0 K) is zero

The third law of thermodynamics is the entropy of a pure, perfect crystalline substance at absolute zero (0 K) is zero

What are the types of molecular motion?

The types of molecular motion are: 1. Translational 2. Vibrational 3. Rotational

What does thermodynamics help us understand? Thermodynamics helps us understand ____ reactions differ in "_________ of reaction" (Keq).

Thermodynamics helps us understand why reactions differ in the "extent of reaction" (Keq).

Thermodynamics includes _____ change, entropy change, and _____ _____ Energy Change.

Thermodynamics includes Enthalpy change, Entropy Change, and Gibbs Free Energy Change.

What is thermodynamics? Thermodynamics is the study of _____ and its _____.

Thermodynamics is the study of energy and its transformations.

Translational molecular motion is the _____ of a molecule from one point to another

Translational molecular motion is the moving of a molecule from one point to another.

True or false. The direction of a spontaneous process can depend on temperature

True the direction of a spontaneous process can depend on temperature

Vibrational molecular motion is the _____ or _____ of bonds

Vibrational molecular motion is the shortening or lengthening of bonds.

When a system is at ____, there will be no change in _____ energy for the system

When a system is at equilibrium, there will be no change in free energy for the system

When studying reactions, what should you ask yourself? 1. How ____ is the reaction? 2. How far to _____ does the reaction proceed? 3. Does the reaction _____?

When studying reactions you, should ask yourself: 1. How fast is the reaction? 2. How far to completion does the reaction go? 2. Does the reaction occur?

What happens to the system when it has a higher temperature than the surroundings? When the system is at a higher temperature than the surroundings, the _______ goes ____of the system into the _______

When the system is at a higher temperature than the surroundings, the energy goes out of the system into the surroundings

What are we really asking when we ask if a reaction occurs? We are really asking if the reaction is ______

When we ask if a reaction occurs, we are really asking if the reaction is spontaneous

Which of the following processes would you predict to be spontaneous? 1. A waterfall runs uphill 2. Gas expands in an evacuated bulb 3. Hot object cools 4. Iron exposed to oxygen and water forms crust 5. Cesium is unreactive in water

Which of the following processes would you predict to be spontaneous? 1. A waterfall runs uphill 2. Gas expands in an evacuated bulb 3. Hot object cools 4. Iron exposed to oxygen and water forms crust 5. Cesium in unreactive in water

Can processes with decreasing entropy still be spontaneous?

Yes, processes with decreasing entropy can still be spontaneous. (criteria for spontaneiety)