1. Density and Pressure

2. Density and Pressure Define density Understand relative density
Define and use the term pressure
Learn the instruments used for measuring pressure
Brownian Motion and the Kinetic Model
Pressure in a Gas
Melting, Boiling and Evaporation

3. Density Mass per unit volume Units: kgm-3, gcm-3, gml-1
Density is changes with temperature
Relative Density
Density of a substance divided density of water
Dimensionless
Density of water is 1000 kgm-3

4. Densities of Some Substances

5. Comparing Densities
When most substances change from a solid state to a liquid state their volume does not change much.
Density of a solid is almost the same as a liquid.

6. Comparing Densities
When a liquid changes into a gas, the spacing between the particles increases by a factor of about ten.
As a result, the density of a substance decreases by a factor of approximately 1000 when it changes from a liquid to a gas.

7. Sample Calculations
A cup of gold colored metal beads was measured to have a mass 425 grams. By water displacement, the volume of the beads was calculated to be 48.0 cm3. Identify the metal.
A 60-ml flask is filled with mercury at 0C. When the temperature rises to 80C, 1.47 g of mercury spills out of the flask. Assuming that the volume of the flask is constant, find the density of mercury at 80C if its density at 0C is 13,645 kgm-3.

8. Pressure Force per unit area Force is normal to the area
Units: Nm-2, kgm-1s-2, Pascal (Pa)
Fluid Pressure
Equation

9. Fluid Pressure
Equation
Absolute pressure
Gauge pressure

10. Measuring Pressure
Mercury Barometer
U-tube Manometer
Equation

11. Sample Calculations
A U-tube contains liquid of unknown density. An oil of density 800 kgm-3 is poured into one arm of the tube until the oil column is 12 cm high. The oil-air interface is 5.0 cm above the liquid level in the other arm of the tube. Find the density of the liquid.
P400, #22.18 (a)

12. Brownian Motion

13. Brownian Motion

14. Brownian Motion Video 1

15. Brownian Motion Video 2

16. Kinetic Theory of Matter
All matter is made up of
a large number of tiny atoms or molecules
which are in continuous motion

17. Pressure of a Gas
Force that the gas molecules exert as they hit the walls of the container

18. Energies and Molecules
Potential Energy
Distance between molecules
Kinetic Energy
Related to temperature of the substance
Internal Energy
The sum of the kinetic and potential energies of a substance.

19. Melting and Boiling Heat is added to break bonds between molecules
Some part of the energy is used to work against the environment
Both occur at a specific constant temperature
Let us look at the energies involved

20. Boiling and Evaporation
Both involve changes from liquid to gas
Boiling occurs at a specific temperature
Evaporation occurs at any temperature
Boiling occurs inside the liquid
Evaporation occurs at the surface of the liquid