Examples of heat capacity in the following topics:
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- The heat capacity measures the amount of heat necessary to raise the temperature of an object or system by one degree Celsius.
- In SI units, heat capacity is expressed in units of joules per kelvin (J/K).
- The heat capacity of most systems is not a constant.
- This defines the heat capacity at constant volume, CV.
- Another useful quantity is the heat capacity at constant pressure, CP.
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- An ideal gas has different specific heat capacities under constant volume or constant pressure conditions.
- The heat capacity at constant volume of nR = 1 J·K−1 of any gas, including an ideal gas is:
- The heat capacity at constant pressure of 1 J·K−1 ideal gas is:
- Measuring the heat capacity at constant volume can be prohibitively difficult for liquids and solids.
- The heat capacity ratio or adiabatic index is the ratio of the heat capacity at constant pressure to heat capacity at constant volume.
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- The heat capacity is an extensive property that describes how much heat energy it takes to raise the temperature of a given system.
- However, it would be pretty inconvenient to measure the heat capacity of every unit of matter.
- This quantity is known as the specific heat capacity (or simply, the specific heat), which is the heat capacity per unit mass of a material .
- The specific heat is the amount of heat necessary to change the temperature of 1.00 kg of mass by 1.00ºC.
- Note that the total heat capacity C is simply the product of the specific heat capacity c and the mass of the substance m, i.e.,
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- The change in temperature of the measuring part of the calorimeter is converted into the amount of heat (since the previous calibration was used to establish its heat capacity).
- Knowledge of the heat capacity of the surroundings, and careful measurements of the masses of the system and surroundings and their temperatures before and after the process allows one to calculate the heat transferred as described in this section.
- The temperature increase is measured and, along with the known heat capacity of the calorimeter, is used to calculate the energy produced by the reaction.
- Bomb calorimeters require calibration to determine the heat capacity of the calorimeter and ensure accurate results.
- The temperature change produced by the known reaction is used to determine the heat capacity of the calorimeter.
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- Calorimetry requires that the material being heated have known thermal properties, i.e. specific heat capacities .
- where δQ is the increment of heat gained by the sample, CV is the heat capacity at constant volume, cv is the specific heat at constant volume, and ΔT is the change in temperature.
- Multiplying the temperature change by the mass and specific heat capacities of the substances gives a value for the energy given off or absorbed during the reaction:
- It does not account for the heat loss through the container or the heat capacity of the thermometer and container itself.
- In addition, the object placed inside the calorimeter shows that the objects transferred their heat to the calorimeter and into the liquid, and the heat absorbed by the calorimeter and the liquid is equal to the heat given off by the metals.
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- Most of the physical properties of superconductors vary from material to material, such as the heat capacity and the critical temperature, critical field, and critical current density at which superconductivity is destroyed.
- For example, the electronic heat capacity is proportional to the temperature in the normal (non-superconducting) regime.
- Behavior of heat capacity (cv, blue) and resistivity (ρ, green) at the superconducting phase transition.
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- As we learned in our Atom on "Heat Engines", all heat engines require heat transfer, achieved by providing (and maintaining) temperature difference between engine's heat source and heat sink.
- Water, with its high heat capacity, works extremely well as a coolant.
- But this means that cooling water should be constantly replenished to maintain its cooling capacity .
- Some may assume that by cooling the heated water, we can possibly fix the issue of thermal pollution.
- However, as we noted in our previous Atom on "Heat Pumps and Refrigerators", work required for the additional cooling leads to more heat exhaust into the environment.
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- A heat pump is a device that transfers heat energy from a heat source to a heat sink against a temperature gradient.
- Heat pumps, air conditioners, and refrigerators utilize heat transfer from cold to hot.
- Actually, a heat pump can be used both to heat and cool a space.
- As with heat pumps, work input is required for heat transfer from cold to hot.
- What is considered the benefit in a heat pump is considered waste heat in a refrigerator.
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- Energy can exist in many forms and heat is one of the most intriguing.
- This module defines and explores heat transfer, its effects, and the methods by which heat is transferred.
- Maxwell outlined four stipulations for the definition of heat:
- After defining and quantifying heat transfer and its effects on physical systems, we will discuss the methods by which heat is transferred.
- So many processes involve heat transfer, so that it is hard to imagine a situation where no heat transfer occurs.
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- In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work.
- In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work .
- We define the efficiency of a heat engine (Eff) to be its net work output W divided by heat transfer to the engine Qh:
- (b) A heat engine, represented here by a circle, uses part of the heat transfer to do work.
- Qh is the heat transfer out of the hot reservoir, W is the work output, and Qc is the heat transfer into the cold reservoir.