Cv and Cp
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Cv and Cp
Dr. Lavelle said that Cp is equivalent to enthalpy change, but why is Cv not included in this?
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Re: Cv and Cp
I think both Cv and Cp can be used to calculator enthalpy change in the formula q= nCT. Just know that Cv means the molar heat capacity of a gas at a constant volume whereas Cp means the molar heat capacity of a gas at a constant pressure.
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Re: Cv and Cp
Since enthalpy change is usually under constant pressure, maybe that's why only Cp equals enthalpy change.
Re: Cv and Cp
Do solids and liquids only use C? Or do they use Cv? I'm pretty sure they don't use Cp.
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Re: Cv and Cp
Leila_4E wrote:Do solids and liquids only use C? Or do they use Cv? I'm pretty sure they don't use Cp.
They are the same for solids and liquids. For gasses, they are easily compressible, meaning their specific volume can easily change, while solids and liquids cannot change volume that easily so we just say that Cv=Cp.
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Re: Cv and Cp
The values are the same in solids and liquids. In gases, Cv is constant volume and Cp is constant pressure so the values will be different. I think Cp may be used because Cp calorimetry gives enthalpy values, whereas Cv calorimetry gives heat capacity of the whole container/all parts
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Re: Cv and Cp
They are equal in the case of solids and liquids but change for gases due to compression and expansion.
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Re: Cv and Cp
The change in enthalpy is equal to heat released or absorbed only when the reaction happens at a constant pressure. So the value of q(heat) calculated by Cp is equal to change in enthalpy, but not by Cv.
Re: Cv and Cp
If I'm not mistaken, Cv is used under constant volume while Cp is used under constant pressure.
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