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Question
Wed August 24, 2011 By:

explain the intensive and extensive properties? derive an expression for a state function H i.e. dH= dU+p(dV) AND dH=dU+dnRT...

Wed August 24, 2011
Properties that do not depend on the amount of the matter present are known as INTENSIVE properties.
Examples are
• Color
• Odor
• Luster - How shiny a substance is.
• Malleability - The ability of a substance to be beaten into thin sheets.
• Ductility - The ability of a substance to be drawn into thin wires.
• Conductivity - The ability of a substance to allow the flow of energy or electricity.
• Hardness - How easily a substance can be scratched.
• Melting/Freezing Point - The temperature at which the solid and liquid phases of a substance are in equilibrium at atmospheric pressure.
• Boiling Point - The temperature at which the vapor pressure of a liquid is equal to the pressure on the liquid (generally atmospheric pressure).
• Density - The mass of a substance divided by its volume
•
Properties that do depend on the amount of matter present are known as EXTENSIVE properties.
Examples are
• Mass - A measurement of the amount of matter in a object (grams).
• Weight - A measurement of the gravitational force of attraction of the earth acting on an object.
• Volume - A measurement of the amount of space a substance occupies.
• Length
The derivation:

According to the first law, dU = dQ - dW        (for any process, neglecting DKE and DPE)

or after putting the value of W, dU = dQ - pdV

Also, we know  H = U + pV therefore dH = dU + pdV + Vdp

so,  dH = dQ - dW + pdV + Vdp (any process)

or

dH = dQ + Vdp (for any quasi-static process)

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