Is heat capacity (C) extensive or intensive? What about specific heat (c) ? Explain briefly.

Short Answer

Expert verified

Heat capacity is an extensive property

Specific heat is an intensive property.

Step by step solution

01

Given Information

Heat Capacity C and

Specific Heat c.

02

Explanation

On the basis of physical properties of matter, it can be classified into two parts

1. Intensive property: It does not depend on the quantity which means the intensive property does not vary when the mass changes.
2.Extensive property: It depends on the quantity of matter which means the extensive property varies when the mass changes.

Specific heat capacity is an intensive property. Specific heat capacity is given by c=Cm

Where c is specific heat capacity, C is the heat capacity, m is the mass.

Here both C and m are extensive properties.
The ratio of two extensive property is intensive property.
This means Heat capacity is an extensive property.

The amount of heat capacity is given byCv=dUdT

Where, U is the internal energy and T is the temperature.
U is an extensive property and T is an intensive property.

The ratio of extensive to intensive results in extensive property.

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Most popular questions from this chapter

In this problem you will derive approximate formulas for the shapes of the phase boundary curves in diagrams such as Figures 5.31 and 5.32, assuming that both phases behave as ideal mixtures. For definiteness, suppose that the phases are liquid and gas.

(a) Show that in an ideal mixture of A and B, the chemical potential of species A can be written μA=μA°+kTln(1-x)where A is the chemical potential of pure A (at the same temperature and pressure) and x=NB/NA+NB. Derive a similar formula for the chemical potential of species B. Note that both formulas can be written for either the liquid phase or the gas phase.

(b) At any given temperature T, let x1 and xgbe the compositions of the liquid and gas phases that are in equilibrium with each other. By setting the appropriate chemical potentials equal to each other, show that x1and xg obey the equations =1-xl1-xg=eΔGA°/RTandxlxg=eΔGB°/RT and where ΔG°represents the change in G for the pure substance undergoing the phase change at temperature T.

(c) Over a limited range of temperatures, we can often assume that the main temperature dependence of ΔG°=ΔH°-TΔS°comes from the explicit T; both ΔH°andΔS°are approximately constant. With this simplification, rewrite the results of part (b) entirely in terms of ΔHA°,ΔHB° TA, and TB (eliminating ΔGandΔS). Solve for x1and xgas functions of T.

(d) Plot your results for the nitrogen-oxygen system. The latent heats of the pure substances areΔHN2°=5570J/molandΔHO2°=6820J/mol. Compare to the experimental diagram, Figure 5.31.

(e) Show that you can account for the shape of Figure 5.32 with suitably chosenΔH° values. What are those values?

The formula for Cp-Cv derived in the previous problem can also be derived starting with the definitions of these quantities in terms of U and H. Do so. Most of the derivation is very similar, but at one point you need to use the relation P=-(F/V)T.

Repeat the preceding problem with T/TC=0.8

Show that equation 5.40 is in agreement with the explicit formula for the chemical potential of a monatomic ideal gas derived in Section 3.5. Show how to calculate μ°for a monatomic ideal gas.

Suppose that a hydrogen fuel cell, as described in the text, is to be operated at 75°Cand atmospheric pressure. We wish to estimate the maximum electrical work done by the cell, using only the room temperature data at the back of this book. It is convenient to first establish a zero-point for each of the three substances, H2,O2,andH2O. Let us take Gfor both H2andO2to be zero at 25°C, so that G for a mole of H2Ois -237KJat 25°C.

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