# helpppp please. nobody can solve it??

• October 29th 2007, 04:09 AM
marikas
helpppp please. nobody can solve it??
this has been solved now
• October 29th 2007, 07:15 AM
earboth
Quote:

Originally Posted by marikas
3. The entropy change, ΔS, associated with the isothermal (i.e.
constant temperature) change in volume of n moles of an ideal

gas from volume V1 to volume V2 is given by the equation
ΔS = nR ln(V2/V1)
where R is the gas constant.
(a) If a compression occurs (V2 < V1) use Equation 1 to deduce
whether there will there be an increase (ΔS is positive) or
decrease (ΔS is negative) in the entropy of the gas.

Hello,

$\Delta S=n \cdot R \cdot \ln \left(\frac{V_2}{V_1}\right)$

If $V_2 < V_1$ then $\frac{V_2}{V_1} < 1$ and then $\ln \left(\frac{V_2}{V_1}\right)<0$ that means negative and therefore the complete product is negative too. Thus $\Delta S$ is negative so there is a decrease in the entropy of the gas.