Thermochemistry and Changes of State - AP Chemistry

Definition of triple point: where solid, liquid, and gas exist in equilibrium

the critical point is where the solid and gas cannot be distinguished

The point detailed in the question is the triple point of water on the phase diagram. At the triple point all three phases of a chemical coexist; as such the correct answer is solid, liquid, and gas.

For this question, we're told that water is boiling and that the pressure above the surface of the water increases. We're asked to find out what will happen to the water.

It's important to remember the definition of a boiling liquid; the vapor pressure of the liquid is equal to the atmospheric pressure above the solution. Thus, if the atmospheric pressure increases, the vapor pressure would then become lower than the atmospheric pressure. As a result, the water would cease to boil. Moreover, its boiling point would increase because a higher temperature would be necessary in order to raise the vapor pressure enough so that it becomes equal to atmospheric pressure.

Definition of triple point: where solid, liquid, and gas exist in equilibrium

the critical point is where the solid and gas cannot be distinguished

The point detailed in the question is the triple point of water on the phase diagram. At the triple point all three phases of a chemical coexist; as such the correct answer is solid, liquid, and gas.

For this question, we're told that water is boiling and that the pressure above the surface of the water increases. We're asked to find out what will happen to the water.

It's important to remember the definition of a boiling liquid; the vapor pressure of the liquid is equal to the atmospheric pressure above the solution. Thus, if the atmospheric pressure increases, the vapor pressure would then become lower than the atmospheric pressure. As a result, the water would cease to boil. Moreover, its boiling point would increase because a higher temperature would be necessary in order to raise the vapor pressure enough so that it becomes equal to atmospheric pressure.

A closed system allows for the exchange of energy between the system and its surroundings, but does not allow the exchange of matter. This is the definition of a closed system. An open system allows for the exchange of both matter and energy between the system and its surroundings. An isolated system on the other hand does not allow the exchange of either matter or energy between the system and its surroundings.

Recall the following equation:

Now, since the bomb calorimeter keeps the volume constant, we know the following relationship:

Thus, we can then write the following equation for :

Start by finding :

From this, we know that

Now, find .

Your answer must have significant figures.

In this question, we're given the mass of copper, along with its specific heat capacity, and we're asked to determine the amount of heat energy necessary to increase its temperature by a given amount.

To solve this problem, we'll need to make use of the following equation.

Since we know what the values are for the mass and specific heat, we'll need to figure out what the temperature will be. Since the Kelvin and Celsius temperature scales both change by the same amount and only differ at their zero point, we can take the difference of the temperatures in degrees Celsius and use that value (since it will be equivalent to the change in the Kelvin temperature as well).

Plugging this information into the first expression, we can solve for the amount of heat energy that will bring this mass of copper to the desired temperature.

the critical point is where the solid and gas cannot be distinguished

Definition of triple point: where solid, liquid, and gas exist in equilibrium

The point detailed in the question is the triple point of water on the phase diagram. At the triple point all three phases of a chemical coexist; as such the correct answer is solid, liquid, and gas.

Recall the equation that gives the relationship between change in temperature and amount of heat:

,

where ,

,

, and

Since the question asks for the final temperature, re-arrange the equation to solve for .

Substitute in the given values to solve for the final temperature.

Recall the equation that gives the relationship between the change in temperature and the amount of heat:

, where

,

, and

Substitute in the given values to find how much heat is required to increase the temperature of the block of lead the specified amount.

Make sure to round the answer to three significant figures.

Recall the relationship between heat and specific heat capacity

Plug in known values and solve for Q

Since Pb starts at a higher temperature than the water, we know that energy (in the form of heat) will be transferred from Pb to water. Due to the law of conservation of energy, the exact same amount of energy lost by Pb must be gained by water.

Recall that

Combining the two equations, we have

Combine like terms then solve for final temperature

For this question, we're given a definition for the specific heat capacity of a substance and we're asked to identify the correct units for this term.

We can also recall the equation that relates all of these terms.

Rearranging this expression to isolate the term for the specific heat capacity gives us the following.

Next, we can recall what units would be appropriate to use for each of the following terms in the above expression. The term represents heat energy added to or removed from the system, so this value would be in units of joules. Next, the term represents the mass of the substance, so grams can be used for this term. Finally, the term represents the change in temperature of the substance, so we can use the absolute temperature in kelvins here.

Putting all this together gives us the following.

In this question, we're presented with a phase diagram and are asked to determine where on the graph the rate of vaporization equals the rate of condensation.

First, it's important to realize that when the rate of vaporization and condensation are equal, we have an equilibrium of liquid and gas phases. In other words, for a given temperature and pressure, the rate at which the liquid evaporates into a gas is exactly equal to the rate at which the gas condenses into a liquid.

On a phase diagram, the area of the upper left portion of the diagram represents the solid state. The middle portion of the diagram represents the liquid state. The bottom and right most part of the diagram represents the gas phase.

Furthermore, each line on the diagram represents the specific combination of temperature and pressure in which a given compound will exist in equilibrium between two phases. The point where all three lines intersect, however, represents the triple point. This tells us the temperature and pressure in which the compound will exist in an equilibrium between all three states.

Because we are looking for the equilibrium line that represents equilibrium of vaporization and condensation, we want the line that separates the liquid portion of the diagram from the gas portion. Based on the identification of regions on the diagram discussed above, that would be line C as shown in the diagram. Line A represents equilibrium between solid and gas (sublimation rate = deposition rate). Line B represents equilibrium between solid and liquid (melting rate = freezing rate).