Reading Quiz

Question 1:

Answer:

1. Heat capacity is the amount of heat needed to raise its temperature, defined by Q/deltaT. Specific heat capacity is the heat capacity per mass. Heat capacity is ambiguous because it changes depending on the quantity of substance; however specific heat capacity provides a correction for substance amount and is unique to the identity of the substance.
2. Heat capacity and specific heat capacity both deal with the amount of heat needed to raise the temperature of a substance and both are ambiguous depending on the condidtions under which the substance is heated. C, the heat capacity, is the about of heat needed to raise the temperature of a substance, per degree temperature increase. c, the specific heat capacity, is the heat capacity per unit mass, and is a more fundamental unit.
3. Heat capacity is the amount of heat needed to raise the temperature of an object per degree. Specific heat capacity is defined as heat capacity per unit mass.
4. Heat capacity is the heat necessary to increase an object's temperature by one degree. Specific heat capacity is the amount of heat necessary per unit mass to raise an object's temperature by one degree; i.e. the heat capacity per unit mass.
5. Capacity is the amount of heat needed to raise the temperature of a substance by a known amount. Heat capacity is the capacity divided by the mass of the substance being heated.
6. The heat capacity of an object is the amount of heat needed to raise its temperature, per degree temperature increase. The specific heat capacity is the heat capacity per unit mass.
7. Heat capacity is the amount of heat needed ro raise an objects temperature per degree increase. Heat capacity and specific heat capacity are really close to being the same thing, except that specific heat capacity is the heat capacity per unit mass.
8. heat capacity is the amount of head needed to raise the temperature of an object (per degree raise in temperature), while specific heat capacity is the heat capacity per unit mass. THis means that specific heat capacity is more of an intrinsic measure than heatcapacity, since it is independent of size.
9. Heat capacity is the amount of heat needed to increase the teperature of a substance by some amount, wheras specific heat capacity is the heat capacity per mass.
10. Heat Capacity-amount of heat needed to raise temperature of an object, per degree temperature Specific Heat Capacity-heat capacity per unit mass, basically; amount of heat needed to raise temperature of an object, per degree temperature, per unit mass
11. The heat capacity is the heat needed to raise the temperature of a substance (per degree). Since this depends on how much of the substance you have, there is the specific heat capacity, which is defined as the heat capacity per unit mass.

Question 2:

Answer:

1. Cv is the heat capacity for a constant volume process and Cp is heat capacity at constant pressure. There is a distinction because no PV work can be done if a process occurs at constant volume. Cp is larger because additional heat must be added to compensate for the loss of energy as work upon expansion.
2. The physical meaning of the distinction between C_v and C_p is to take into account the differences in energy changes caused by heating under the conditions of constant volume and constant pressure. This distinction is made to determine what types of energy and heat are going into and out of the system. C_p is larger.
3. C_V is heat capacity at constant volume and C_P is heat capacity at constant pressure. These are used to describe different situations. The former describes when no work is being done on the system, and the latter describes when expansion work must be done while heating. For an ideal gas C_P = C_V + Nk, so C_P is larger.
4. For C_V, the object is kept at constant volume when the heat capacity is measured. For C_P, the pressure is kept constant when the heat capacity is measured. The most general definition of C is vague, so C_V is not equal to C_P (C_P is larger).
5. Cp= heat capacity at a constant pressure Cv= heat capacity at a constant volume Cp and Cv reactions are very different in nature, for example a Cp reaction will cause the vessel of the reactrive gas to interact with the outside world via enthalpy, where a Cv reaction does not effect the world in this way. Cp is larger (equation 1.48 shows this)
6. Cv is heat capacity at constant volume, Cp is the heat capacity at constant pressure. This distinction is needed because these two C's relate to different circumstances. Cp is greater than Cv.
7. Cv is the heat capacity at constant volume and Cp is the heat capacity at constant pressure. Cp is larger because after some equation manipulation you can find that Cp = Cv + Nk
8. C_v is a constant volume capacity, where there can be no work done on the system since V is constant (so all energy entering system is heat, which leads to the heat capacity). C_p is a constant pressure capacity, which means that only temperature and volume change in your system. We make this distinction since there is a difference on how much work or heat influences the raising of temperature and because the heat capacity by itself is ambiguous. C_p is larger because it must incorporate heat from the loss of work due to expansion.
9. C_p requires extra energy to keep pressure constant in addtion to changing the temperature. This distinction is made because C_p requires this extra term and C_v does not. C_p is larger because of this extra term.
10. They are both heat capacities, but Cv is for constant volume and Cp is for constant pressure. There are differences in the way things heat based on the environment around the object. Cp is larger since Cp=Cv+Nk.
11. Cv is the heat capacity at constant volume, which is the energy needed to raise the temperature while the volume remains fixed (and no work is being done on the system). Cp is the heat capacity at constant pressure, and is larger than Cv, because it takes into account the work that is done by the gas on its environment as its volume expands.

Question 3:

Answer:

1. It is the amount of heat per mass required to complete a phase transition. Heat capacity does not apply to this situation because no temperature change occurs.
2. Latent heat is the amout of heat required to melt or boil a substance, divided by its mass.
3. Latent heat is the heat heat needed to completely accomplish a phase transformation per unit mass.
4. Latent heat is the heat per unit mass required to complete a phase transformation.
5. The amount of heat needed to change the phase of a substance divided by the mass of the substance.
6. Latent heat is the amount of heat required to melt or boil a substance divided by the mass of that substance.
7. Latent heat is the amount of heat required to melt or boil (I think it's the same for freezing and condensation) a substance divided by the mass of the substance.
8. Latent heat is the heat required to melt or boil a substance completely per unit mass. (and heat gain from freezing or condensing).
9. Latent heat is the heat needed to accompish a phase transformation.
10. THe amount of heat required for a material to go completely through a phase transformation, divided by mass.
11. Latent heat is the heat required (per unit mass) to accomplish a complete phase transition. This is important since during a phase transition, the temperature remains constant regardless of how much heat is added, resulting in an infinite heat capacity.

Question 4:

Answer:

1. I find it easier to wrap my mind around an enthalpy change instead of enthalpy as a property. In this way thinking of the change in enthalpy as the heat supplied at constant pressure makes sense to me. Enthalpy is a useful concept because a change in enthalpy is caused only by heat and non-expansion/compression work. It is more useful than energy as a measurement of how much heat goes into or out of a system.
2. Enthalpy is the amount of energy needed to create a hole in space such that an object can be put there, and enough energy for that object to exist without being crushed by the surrounding atmosphere. The concept of enthalpy is useful because it shows that the relationship between an object and its atmosphere is not only pressure-dependent, but also dependent on the energy and the volume that that object occupies.
3. Enthalpy H is total energy needed to create a system. One needs both the energy of the system U and the expansion work PV to make space for the system. The concept is useful because the change in enthalpy tells use directly how much heat has been added to a system.
4. Enthalpy is the total energy of a system plus the work required to move the atmosphere out of the volume it occupies (H = U + PV).
5. Enthalpy is the total amount of energy needed in a Cp reaction. For example, the enthalpy for blowing up a baloon is equal the the amount of work needed to blow up the balloon, plus the amount of work needed to displace all the air outside the balloon to make space for all the new volume.
6. The total energy contained within a system plus the energy the environment exerts on the system or vice versa.
7. Enthalpy is the equation H = U + PV. What this means is that Enthalpy is not only the total energy of the object, but also the work needed to bring that object into it's environment. The PV could be thought of the amount of work needed to push air out of the way to make way for the objects existance (like the wizard and bunny). It is useful (i guess) because of the equation delta_H = Q + W_other. If there is no work besised compression/expansion done on the gas, if we know the change in Enthalpy we can know the change in heat.
8. Enthalpy is the energy of the system plus the expansion work needed to make room for the system, describing the total energy of the system at any stage of expansion. This is useful because you can calculate delta-H instead of delta-U and not worry about expansion work via eq. 1.55. This is useful especially when no other type of work is done on the system, since then delta-H = Q...
9. Enthalpy is the sum of the potential energy of a system plus the potential energy the system has from gas displacement. Enthalpy is useful for constant pressure processes. It is also fun to say. Enthalpy!
10. Since two objects cannot take up the same space, you must consider this when bringing in or taking away energy. Work is required to do this, so you must take that into account. You can use this to figure out how much energy and work it takes to form compounds out of elements as well as many other useful things.
11. Enthalpy is a quantity related to the total energy of a system, which also takes into account the work necessary to displace the air that would otherwise occupy the space taken up by the system. Enthalpy is a convenient tool to use when dealing with compression and expansion under constant pressure.

Question 5:

Answer:

1. Enthalpy, with emphasis on its physical meaning. Its use in calculations is relatively clear.
2. While I know that rubbing my hands together increases the temperature of my hands without heat, I am still uncertain as to how temperature can increase without application of heat. Is temperature a measure of how heat is spontaneously given up or absorbed in a system?
5. More explanation of why we distinguish between Cp and Cv reactions.
6. The definition of enthalpy is not quite clear but the equation makes it understanbable.
7. Give more uses of enthalpy, it seems kind of pointless and i've never really seen it used.
8. nope
9. degrees of freedom.
10. Cv and Cp
11. There's so many definitions and forms of heat capacity, it's a little confusing to understand when to use each one.