Catalyst1. 10 L of an unknown gas has a mass of 10.8

grams at a temperature of 310 K and 1.2 atm. What is the molar mass of this mass? What is the identity of the gas?

Loose EndsLabs and Lab Write – Ups

The only way you learn from labs is through the analysis

These are not meant to torture. They honestly help with the content.

E.g. Net Ionic Equation LabLab Reports

Human Error – Don’t want to see it ever again in a report…you can’t BS a teacher that made it through education using the same BS.

Plagiarism New Lab Report/Write-Up Policy

You call mom/dad/guardian to explain why your don’t value your education

No lab write up = No lunch/nutrition You will do the write up during lunch/nutrition, but you

will not get the points

J – TPSIf the atmosphere at 120,000 ft contained

oxygen, nitrogen, and hydrogen at pressures of 0.0002 atm, 0.0003 atm, and 0.0001 atm, then what is the pressure of the atmosphere at this height?

Lecture 4.2 – Partial Pressures and Deviations from Ideality

Today’s Learning TargetsLT 4.4 – I can discuss Dalton’s Law of Partial

Pressures. Additionally, I can calculate partial pressures for a gas mixture

LT 4.7 – I can compare and contrast ideal and real gases. I can discuss how the Van der Walls equation corrects for these deviations from ideality.

Dalton’s Law of Partial PressuresThe total pressure of a mixture of gases equals

the sum of all the partial pressuresThis means that we can add up all the

individual pressures (partial pressures) to get the overall pressure of a system.

Class ExampleA mixture of 6.00 g O2 (g) and 9.00 g CH4 (g) is

placed in a 15.0 L vessel at 0 oC. What is the partial pressure of each gas, and what is the total pressure in the vessel?

Table TalkWhat is the total pressure exerted by a mixture

of 2.00 g of H2 and 8.00 g of N2 at 273 K in a 10.0 L vessel.

Mole FractionsBecause each gas acts independently even

when mixed, we can relate the amount of moles of gas in a mixture.

The mole fraction (X) expresses the ratio of moles of gas to total moles of gas in the system

€

X1 =moles of compound 1

total moles=n1

nt

Class ExampleA study of the effects of certain gases on plant

growth requires a synthetic atmosphere composed of 1.5 mol percent CO2, 18.0 mol percent O2, and 80.5 mol percent Ar. Calculate the partial pressure of O2in the mixture if the total pressure of the atmosphere is to be 745 torr.

Table TalkThe composition of the atmosphere of Saturn’s

moon Titan has been estimated. The pressure on the surface of Titan is 1220 torr. The atmosphere consists of 82 mol percent N2, 12 mol percent Ar, and and 6.0 mol percent CH4. Calculate the partial pressure of each gas.

Collecting Gas Over WaterIn most labs, we bubble gas through water and

catch it in some vessel. This is known as collecting a gas over waterWe must correct for the pressure of the water

vapor that is present in the air above where the gas was collected

€

Ptotal = Pgas + PH2O

Pgas = Ptotal − PH2O

Class ExampleWhen a sample of KClO3 is partially

decomposed, O2 is produced and the gas is collected over water. The volume of the gas collected is 0.250 L at 26 oC and 765 torr. How many moles of O2 are collected? NOTE – At 26 oC, the PH2O is 25 torr.

Table TalkAmmonium nitrate decomposes on heating to

form N2 gas:

NH4NO2 (s) N2 (g) + 2H2O (l)

When a sample of NH4NO2 is decomposed

Collaborative PosterIn a group of three, analyze and solve the

problems given to you.Assign person A, B, and C in your group

Person A – Identify the values for all variables and givens in the problem

Person B – Identify and write the equations that you will need to use to solve these problems

Person C – Solve the problem.

1.2 I- + Pb2+ PbI22. Cs2O + H2O 2CsOH

3.2 H+ + ZnS H2S + Zn2+

Lab 8 – Molar Mass of Butane Gas

Lab Work Time

Work TimeFor the remainder of class, please begin your

homework that will be due Thursday/Friday

Closing TimeClosing TimeRead 10.6 and answer essential questions on

reading guideComplete book questions: 10.63, 10.65,

10.66, 10.69, 10.71, 10.73, and 10.74