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.

Start by writing the balanced equation for the combustion of hexane:

Recall the following equation:

Remember that energy is required to break bonds, so  should be positive. Energy is also released when bonds are made so  should be negative.

Next, draw out the Lewis structures of each molecule to figure out the number of bonds made or broken.

For the hexane, there are   bonds that must be broken, and   bonds that must be broken.

For each oxygen, there is only 1 oxygen double bond to break. However, we will need to multiply this number by its stoichiometric coefficient.

For each carbon dioxide, there are  double bonds between carbon and oxygen to break. For the given equation, there are  total of these double bonds because we have  moles of carbon dioxide.

For each water, there are  single bonds between hydrogen and oxygen. For the given equation, there are a total of  of these bonds because we have  moles of water.

Now, use the given information regarding to average bond enthalpies to find the change in enthalpy for the reaction.

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.

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.

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

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.

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).