Molar heat capacity at constant volume

• LivvyS
In summary, molar heat capacity at constant volume is the amount of heat energy needed to raise the temperature of one mole of a substance while keeping the volume constant. This is different from molar heat capacity at constant pressure, which allows for volume changes. It is an important property for understanding substance behavior and is typically measured using specialized equipment. Factors such as substance type, molecular structure, temperature, pressure, and impurities can affect molar heat capacity at constant volume.
LivvyS
Hi everyone,

If you know the temperature rise of 2 moles of an ideal gas when a known amount of energy is transferred to it as heat, (hence are able to calculate cv by dU/dT); is the molar heat capacity simply half this value as it is half the number of moles?

If the process takes place at constant volume, yes.

Is the same true of heat capacity at constant pressure?

LivvyS said:
Is the same true of heat capacity at constant pressure?
Yes.

Hello,

That is correct. The molar heat capacity at constant volume, denoted as Cv, is defined as the amount of heat required to raise the temperature of one mole of a substance by one degree Celsius at constant volume. In the case of an ideal gas, the internal energy (U) is directly proportional to the temperature (T), so the slope of the U-T graph is equal to Cv. Since you are considering 2 moles of the gas, the molar heat capacity would indeed be half of the value calculated for one mole. This is because the internal energy and temperature of the gas are directly related to the number of moles, so doubling the number of moles would result in double the internal energy and temperature change. I hope this helps clarify your understanding of molar heat capacity at constant volume. Let me know if you have any further questions.

1. What is molar heat capacity at constant volume?

Molar heat capacity at constant volume is the amount of heat energy required to raise the temperature of one mole of a substance by one degree Celsius while keeping the volume constant.

2. How is molar heat capacity at constant volume different from molar heat capacity at constant pressure?

Molar heat capacity at constant pressure is the amount of heat energy required to raise the temperature of one mole of a substance by one degree Celsius while allowing the volume to change. This means that the substance can expand or contract during the heating process, unlike in constant volume conditions.

3. What is the significance of molar heat capacity at constant volume?

Molar heat capacity at constant volume is an important property for understanding the behavior of substances when heated. It helps determine the amount of heat energy needed to raise the temperature of a substance and can also provide information about the internal energy and molecular structure of the substance.

4. How is molar heat capacity at constant volume measured?

Molar heat capacity at constant volume is typically measured using specialized equipment such as a bomb calorimeter. The substance is placed in the calorimeter and heated to a known temperature. The amount of heat energy absorbed by the substance is then measured and used to calculate the molar heat capacity.

5. What factors can affect molar heat capacity at constant volume?

The molar heat capacity at constant volume of a substance can be affected by various factors, including the type of substance, its molecular structure, and its temperature. Other external factors such as pressure and impurities can also impact the molar heat capacity.

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