Concepts to Rvw Pressure –Stand demo –Sound demo Units of pressure –Pa –mm Hg –torr –atm –psi.

Concepts to Rvw• Pressure

– Stand demo– Sound demo

• Units of pressure– Pa– mm Hg– torr– atm– psi

Conversions in Pressure

1 atm = 760 mm Hg

1 atm = 760 torr

1 atm = 1.01 x 105 Pa or 101 kPa

1 atm = 14 psi

Practice

1. Convert 1.75 atm to kPa.

2. Convert 1.75 atm to mm Hg.

Hmmmm?Why do you almost close your

mouth and blow when you have a burn on your skin to cool it?

Why do you open your mouth wider when you want to warm your hands?

Run through of laws• Equation to know:

P1V1 = P2V2 T must be in Kelvin

T1 T2

• Dalton’s law of partial pressures (duh) next

• Boyle’s law (last class) next

• Charles’ law next

• Gay-Lussac (what you will design) next

Dalton’s Law• Gas collection thru water• Pros• Cons • Table A-8 in appendix APg 859

How to do Dalton’s law problems

• Sample prob B

PT = Pgas + PH2O

Practice prob pg 367

Givens Eq’n

T = 20 oC

Pressure =

Partial press of H = 742.5 torr

Partial press of water = 17.5 torr

?? = room pressure at time

Pg 367 #5

Givens

T = 23 oC

Room pressure = 785 mmHg

Partial pressure of water = 21.1 mm Hg

??? Partial pressure of nitrogen

back

Boyle’s Law• Why does it get harder squeeze as the

volume decreases?

• How does this fit with breathing?

• back

Charles’ Law

• Dillon’s story—why everyone should know science

• Earlier aviation people used balloons

• Reason for Kelvin scale and absolute zero

• back

Guy-Lussac

• Using the pressure sensors, thermometers and a bottle of club soda determine how you can verify G-L law.

• You will need other materials but the set-up if for YOUR group to determine.

Gas Volumes

Noticed early on volumes didn’t addWater example

Molar mass of gases = set volume# =

Practice

What volume does 0.68 mol of gas occupy at STP?

What quantity of gas, in moles, is 2.21 L @ STP?

Pg 392 # 43 more practice

Gas Stoichiometry

Propane is use in gas grills. The complete combustion of propane is given by the following:

C3H8 + 5 O2 3CO2 + 4 H2O

What volume, in liters, of oxygen is needed for the complete combustion of 0.35 L of propane?

Pg 382 Practice

What volume of oxygen gas is needed to react completely with 0.626 L of CO to form carbon dioxide? Assume all volume measurements are made at the same temperature and pressure.

Pg 382Nitric acid can be made by the reaction of

gaseous nitrogen dioxide with water according to the following reaction:

3NO2(g) + H2O(l) 2 HNO3(l) + NO(g)

If 708 L of NO2 react with water, what volume of NO will be produced? Assume all measurements are at same temp and pressure.