Laws of Thermodynamics - AP Chemistry

The entropy cannot decrease in an isolated system because the energy can only be degraded. Since the system is isolated, no higher-grade energy—or any energy at all—is being introduced into the system. As a result, the entropy cannot decrease. The other answer choices relate to the other laws of thermodynamics.

Standard states are defined as a specific set of conditions, such as when a gas is at , concentration, and .

Standard enthalpy of formation, the energy required for form 1 mole of a compound from its constituent elements, occurs when elements are in their standard states.

is positive because heat flows into the system to raise the temperature of the water.

Use the equation that relates heat, mass, specific heat, and change in temperature:

There are four main laws of thermodynamics, which describe how temperature, energy, and entropy behave under various circumstances. The zeroth law of thermodynamics helps to define temperature; it states that if two systems are each in thermal equilibrium with a third system, they must be in thermal equilibrium with each other. The first law of thermodynamics negates the possibility of perpetual motion; it states that when energy passes into or out of a system, the system's internal energy changes in accord with the law of conservation of energy. The second law of thermodynamics also negates the possibility of perpetual motion; it states that in a natural thermodynamic process, the sum of the entropies of the interacting systems increases. Lastly, the third law of thermodynamics states that the entropy of a system approaches a constant value as the temperature nears absolute zero.

The second law of thermodynamics states that the entropy of the system and the entropy of the surroundings is equal to the entropy of the universe. The rest of the answer choices are not one of the fundamental laws of themodynamics.

First law of thermodynamics states that the energy of the universe is always constant. This is called the conservation of energy. The total energy of the universe is defined as follows:

According to the law, energy gained or lost by a system is reciprocated by its surroundings. This means that energy, such as heat energy, lost by the system will be gained by the surroundings. This will keep the total energy constant. Energy can be converted from one form to another (such as from kinetic to potential); however, it cannot be created or destroyed.

The second law of thermodynamics states that the disorder of the universe is always increasing. As mentioned, energy can never be created, nor destroyed. In an exothermic reaction, heat energy is transferred from the system to the surroundings. In an endothermic reaction, heat energy is transferred from the surroundings to the system.

Entropy is a measure of disorder; therefore, a substance with low entropy will be highly ordered. Gases have the highest entropy because the molecules are spread far apart and are more chaotic. Solids, on the other hand, have the least entropy because they are typically found in an ordered, lattice structure with very little chaos. A freezing reaction involves conversion of a liquid to a solid; therefore, the product of this reaction will have the lowest entropy.

The third law of thermodynamics states that a perfect crystal at absolute zero ( or ) has an entropy of zero (lowest possible entropy). Note that entropy can never be less than zero.

Microstates are microscopic configurations of a substance, and relates directly to the entropy of the system. The more microstates, the higher the entropy. Since this substance has the lowest entropy it will have the least amount of microstates.

To understand the relationship between Gibbs free energy and enthalpy, we need to look at the following equation:

Here, is change in Gibbs free energy, is enthalpy, is change in entropy, and is the temperature in Kelvin. From the given information, we know that both temperature and entropy are zero; therefore, Gibbs free energy equals the enthalpy for this substance.

In order to solve this problem, we'll need to break it up into steps.

Step 1: Calculate the amount of energy necessary to raise the sample of ice from to . To do this, we'll need to use the following equation:

Step 2: Calculate the amount of energy necessary to convert the sample at from ice to water. We'll need to make use of the following equation:

Step 3: Calculate the amount of energy necessary to convert the sample of water from to .

Step 4: Sum the amount of energy from the previous 3 steps. This value is the total amount of energy for the entire process.

Step 5: Now that we know the total amount of energy needed for the process, we need to calculate the time based on the amount of power provided.

The second law of thermodynamics states that the entropy of the system and the entropy of the surroundings is equal to the entropy of the universe. The rest of the answer choices are not one of the fundamental laws of themodynamics.

First law of thermodynamics states that the energy of the universe is always constant. This is called the conservation of energy. The total energy of the universe is defined as follows:

According to the law, energy gained or lost by a system is reciprocated by its surroundings. This means that energy, such as heat energy, lost by the system will be gained by the surroundings. This will keep the total energy constant. Energy can be converted from one form to another (such as from kinetic to potential); however, it cannot be created or destroyed.

The second law of thermodynamics states that the disorder of the universe is always increasing. As mentioned, energy can never be created, nor destroyed. In an exothermic reaction, heat energy is transferred from the system to the surroundings. In an endothermic reaction, heat energy is transferred from the surroundings to the system.

Entropy is a measure of disorder; therefore, a substance with low entropy will be highly ordered. Gases have the highest entropy because the molecules are spread far apart and are more chaotic. Solids, on the other hand, have the least entropy because they are typically found in an ordered, lattice structure with very little chaos. A freezing reaction involves conversion of a liquid to a solid; therefore, the product of this reaction will have the lowest entropy.

The third law of thermodynamics states that a perfect crystal at absolute zero ( or ) has an entropy of zero (lowest possible entropy). Note that entropy can never be less than zero.

Microstates are microscopic configurations of a substance, and relates directly to the entropy of the system. The more microstates, the higher the entropy. Since this substance has the lowest entropy it will have the least amount of microstates.

To understand the relationship between Gibbs free energy and enthalpy, we need to look at the following equation:

Here, is change in Gibbs free energy, is enthalpy, is change in entropy, and is the temperature in Kelvin. From the given information, we know that both temperature and entropy are zero; therefore, Gibbs free energy equals the enthalpy for this substance.

In order to solve this problem, we'll need to break it up into steps.

Step 1: Calculate the amount of energy necessary to raise the sample of ice from to . To do this, we'll need to use the following equation:

Step 2: Calculate the amount of energy necessary to convert the sample at from ice to water. We'll need to make use of the following equation:

Step 3: Calculate the amount of energy necessary to convert the sample of water from to .

Step 4: Sum the amount of energy from the previous 3 steps. This value is the total amount of energy for the entire process.

Step 5: Now that we know the total amount of energy needed for the process, we need to calculate the time based on the amount of power provided.

The entropy cannot decrease in an isolated system because the energy can only be degraded. Since the system is isolated, no higher-grade energy—or any energy at all—is being introduced into the system. As a result, the entropy cannot decrease. The other answer choices relate to the other laws of thermodynamics.

Standard states are defined as a specific set of conditions, such as when a gas is at , concentration, and .

Standard enthalpy of formation, the energy required for form 1 mole of a compound from its constituent elements, occurs when elements are in their standard states.

is positive because heat flows into the system to raise the temperature of the water.