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Author Topic: Difference between heat capacity and specific heat.  (Read 20305 times)

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Boxxxed

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Difference between heat capacity and specific heat.
« on: October 29, 2010, 01:32:25 PM »

I don't quite understand what heat capacity is despite reading many definitions on the net. I am asked to calculate heat capacity of a heated metal that has been dropped in cold water. I've calculated the specific heat from change in enthalpy which is 4.7 JgC. Is there some sort of conversion?

How does heat capacity disregard mass and still make sense. The greater the mass the more energy it would take to raise the temperature of that body.
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rabolisk

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Re: Difference between heat capacity and specific heat.
« Reply #1 on: October 29, 2010, 02:14:36 PM »

The unit for specific heat is J/(g*K). The unit for heat capacity is J/K. It should be simple how to go from one to another.

The biggest source of confusion is that a lot of people use the terms interchangeably. Often times heat capacity is used to describe specific heat capacity, molar heat capacity, and volumetric heat capacity, even though that is not exactly correct.
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opti384

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Re: Difference between heat capacity and specific heat.
« Reply #2 on: October 29, 2010, 05:47:04 PM »

The definition of specific heat is the amount of heat required to raise the temperature of 1g of the substance.

The definition of heat capacity is just the amount of heat required to raise the temperature.

In this sense, specific heat could be one kinds of many forms of heat capacity such as molar heat capacity and volumetric heat capacity.

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Re: Difference between heat capacity and specific heat.
« Reply #3 on: October 29, 2010, 07:07:01 PM »

Any amount of heat will raise the temperature, so I don't follow
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Borek

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Re: Difference between heat capacity and specific heat.
« Reply #4 on: October 29, 2010, 09:47:54 PM »

The greater the mass the more energy it would take to raise the temperature of that body.

Heat capacity of a piece of a metal is FOR A GIVEN MASS of that piece.

Heat capacity of a 100g piece of a metal is different from heat capacity of a 50g piece of the metal, each piece has its own heat capacity, which is characteristic to this piece only (and to all pieces that have exactly the same mass).

Heat capacity of a calorimeter is sum of heat capacities of all elements - they may differ in specific capacity, but each has given, constant mass, so its heat capacity is constant.

Difference between specific heat capacity and heat capacity is identical to difference between concentration and amount of substance - one is intensive, other extensive property.
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Re: Difference between heat capacity and specific heat.
« Reply #5 on: October 30, 2010, 07:18:44 AM »

so would heat capacity be specific heat multiplied by the mass of the object?
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Borek

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Re: Difference between heat capacity and specific heat.
« Reply #6 on: October 30, 2010, 07:58:08 AM »

Yes. I told you that in the other thread.
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Re: Difference between heat capacity and specific heat.
« Reply #7 on: October 31, 2010, 10:58:49 AM »

I looked it over again, I understand now, thanks
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