{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Chapter 9

# Chapter 9 - The Gaseous State Just as we can understand...

This preview shows pages 1–9. Sign up to view the full content.

The Gaseous State Just as we can understand structure and bonding from a molecular point of view, so we can also understand the properties of matter from a molecular perspective. This is the essence of the kinetic molecular theory of matter The connection between microscopic structure and macroscopic properties is termed statistical mechanics and pervades all aspects of science from chemistry to biology to integrated circuits. To understand how macroscopic properties arise from the structure and interactions of molecules it is easiest to start in the gas phase because: The densities of gases are much lower than solids and liquids and this means that the interactions between molecules can be simplified as they are on average a long way from each other

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Air (Best Known Gas)
Pressure and Temperature Dependence At sufficiently low densities, all gases behave in the same way. This is a consequence of the fact that under these conditions the forces between molecules are relatively unimportant and thus each gas behaves much like another. This allows us to generalize their properties. The volume of a gas represents the amount of space occupied The pressure exerted by the gas is defined by the force exerted per unit area Pressure = Force/Area Gas

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Units of Pressure Are Varied
PV = Constant In the 17th century the English scientist Robert Boyle noticed that if he compressed a gas by increasing the pressure that the volume would contract in such a way that the product of the pressure and volume remained constant: PV = Constant (Boyle’s Law) Increase Pressure

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
PV = Constant (C) The value of the constant C was also found to depend on the temperature and the amount of gas in the container (i.e. the number of moles, n) There are a number of ways to demonstrate the validity of Boyle’s law graphically
The Ideal Gas Law For a fixed pressure and amount of gas it has been observed that Volume of Gas (V)  Temperature (T) Where Temperature is in Kelvin; T(K) = 273.15K + T(C) Since we also know from Boyle’s law that; PV = Constant e can combine these various relationships to deduce the ideal gas la PV = nRT R – universal constant – 0.08206 L atm mol-1 K-1 From Avogadro’s hypothesis we also know that Volume of Gas (V)  n (number of moles of gas in volume V)

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Using PV = nRT A balloon filled with He has a volume of 1.0 x 104L at 1.00atm and 30C (303K). What is the volume of the balloon when it rises to an altitude where the pressure is 0.60atm and the temperature is -20C (253K), assuming that the pressure inside and outside the balloon is the same.
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern