1. States of Matter & Gases

2. States of Matter
The three states of matter include: Solid: Liquid: Gas
State
Volume
Shape
Solid
definite
Liquid
indefinite
Gas

3. Energy and phase change
When Heated:
Solid  liquid  gas
When Cooled:
Gas  liquid  solids

4. Energy & phase change

5. Heating Curve & phase changes
Substances can exist in three states. They are solid, liquid, and gas. They (the substances) change when the kinetic energy of a substance changes.
When a substance changes from a solid to a liquid, it is called melting.
When a substance changes from a liquid to a gas, it is called vaporization.
Gas particles have the most kinetic energy of the three states, but they also have the lowest potential energy. This is opposite of a solid which has high potential energy but low kinetic energy.
There is one special phase change which is not common. The change is from a solid to a gas. This is called sublimation.

6. Heating Curve of Water:
Temperature
0° C --
Energy added 

7. Heating Curve of Water Each plateau represents a physical change .
The energy that is added is used to change the state of water.
Each slope represents the increase in temperature.
The energy that is added is used to heat the of water.

8. Gases: Parameters used to describe Gases:
The variables used to describe the properties of a gas include:
P = Pressure
V = Volume
T= Temperature
n = moles (amount)

9. Temperature:
Temperature (T): must be described using the unit Kelvin (K).
K = °C °C = K – 273
You try: °C = _______ K
298 K
K = _________ °C
177 °C

10. Pressure:
Pressure (P): measures the force/area in units of atm., mm Hg or kPa
1 atm = 760 mm Hg = kPa
Now you try! Convert atm to mm Hg
722 mmHg
2. Convert 0.95 atm to kPa
96.2 mmHg
3. Convert kPa to mmHg
754 mmHg

11. Volume: Volume (V): is defined using milliliters (mL) or liters (L)
1000 mL = 1L
Now you try! mL = _________ L
.150L
L = __________ mL
34,500 mL

12. Atmospheric Pressure:
Atmospheric pressure: is the pressure exerted by the weight of air in the atmosphere. Traditionally it is measure using a barometer.

13. Does atmospheric pressure really exist?
Collapsing Can experiment:
Objective- to prove that atmospheric pressure exists.
Fill in the remaining part of this experiment together in class:
Background to experiment:
Observations:
Interpretation of findings:

14. Gas Laws: P1V1= P2V2 Boyle’s Law
Describes the inverse (  )relationship of pressure: volume
P1V1= P2V2

15. Sample calculation: Boyle’s Law
A gas has an initial pressure of 1.0 atm and a volume of 1.5L. What is the new volume when the pressure is increased to 1.2 atm?
P1 = 1.0atm
V1 = 1.5L
P2= 1.2 atm
V2= ?
Answer: V2= 1.25L

16. Gas Laws:
Charle’s Law
Describes the direct relationship between temperature and volume ( ).
V1 = V2
T1 T2
Remember: Temperature is defined by Kelvin (K = °C + 273)

17. Sample calculation: Charles's Law
A gas has an initial temperature of 275K and a volume of 0.45L. What is the new volume when the temperature is increased to 300K?
V1 = 0.45L
T1 = 275K
T2 = 300K
V2 = ?
Answer : 0.49L

18. The combined gas law
The combined gas law pulls together the inverse relationship of P:V and the direct relationship of V:T
The combined gas law:

19. Combined gas law: V2 = P1V1 T2 T1 P2
P1= 1.5 atm P2 = ? V1 = 0.75L V2 = 1.25L T1 = 276K T2 = 295K
V2 = P1V1 T2
T1 P2
Answer = 0.96 atm

20. The Ideal Gas Law: PV = nRT Includes the amount of a gas in moles (n)
P= pressure (atm)
V= volume (L)
n = moles
R = gas constant: L atm/ mole K
T = temperature (K)

21. Practice problem:
Calculate the pressure of moles nitrogen gas in a 10.0L container, held at 298K.
P= ?
V = 10.0L
n = mole
T = 298K
R = L atm/mole K
P = nRT V
Answer = 1.22 atm

22. Gas law applications:
Mountaineering Scuba Diving Hot Air balloons Tire pressure