Is heat capacity dependant on volume or pressure?

In summary, there are two types of specific heats - constant pressure and constant volume - for all substances, but they only have a clear relationship in ideal gases. For liquids and solids, the difference between the two is minimal and usually not significant in chemistry, except for high pressure reactions.
  • #1
Nikitin
735
27
hi. When you're given molar heat capacity for a substance, is it when under constant pressure or when under constant volume? Like water's heat a capacity when gaseous is 75kJ/mol - is this under constant volume?

For an ideal gas, the formula for heat capacity under constant pressure is: Cp = Cv + R. Is there something similar with liquids?

Please explain this to me, as I'm very confused about all this stuff...
 
Chemistry news on Phys.org
  • #2
Yes, there are separate constant pressure and constant volume specific heats for all substances, but only for gases (and only when their behavior is close to ideal) the dependence is nice and clear.
 
  • #3
For liquids and solids the difference between C_p and C_V is small and seldomly matters in chemistry, maybe with the exception of high pressure reactions.
 

1. What is heat capacity?

Heat capacity, also known as thermal capacity, is the amount of heat energy required to raise the temperature of a substance by one degree Celsius.

2. Is heat capacity dependent on volume or pressure?

Heat capacity is dependent on both volume and pressure. This is because both volume and pressure affect the density of a substance, which in turn affects its ability to store heat energy.

3. How does volume affect heat capacity?

As volume increases, the density of a substance decreases. This means that there are fewer particles in a given space, resulting in less heat energy being required to raise the temperature of the substance. Therefore, heat capacity decreases with increasing volume.

4. How does pressure affect heat capacity?

As pressure increases, the density of a substance increases. This means that there are more particles in a given space, resulting in more heat energy being required to raise the temperature of the substance. Therefore, heat capacity increases with increasing pressure.

5. Can heat capacity be calculated?

Yes, heat capacity can be calculated using the formula C = Q/ΔT, where C is heat capacity, Q is the amount of heat energy transferred, and ΔT is the change in temperature. However, it is important to note that heat capacity may vary depending on the conditions of the substance, such as its volume and pressure.

Similar threads

I Questions about my Understanding of Thermodynamics and Statistical Mechanics
    • Thermodynamics
Replies
2
Views
486
Calculating time to reduce alcohol in wine using heating method
    • Chemistry
4
Replies
131
Views
4K
A What is the heat capacity of water in meta-stable equilibrium?
    • Classical Physics
Replies
2
Views
442
I How to understand experiment to measure heat capacity of solid?
    • Classical Physics
Replies
1
Views
611
I Cannot understand formula for molar heat capacities of an ideal gas
    • Thermodynamics
Replies
22
Views
2K
Heat released during combustion at constant pressure vs volume
    • Chemistry
Replies
6
Views
5K
The specific heat capacity at constant volume for liquid isopropanol?
    • Chemistry
Replies
10
Views
4K
Why does the pressure-volume-constant of Helium increase?
    • Chemistry
Replies
3
Views
1K
What does "limit of zero pressure" mean for ideal gas temperature?
    • Chemistry
Replies
14
Views
2K
Specific Heat Capacity Derivation
    • Introductory Physics Homework Help
Replies
4
Views
974

Hot Threads

Recent Insights

Back
Top