Unit1Day3-LaBrake Wednesday, September 04, 2013 5:19 PM Vanden Bout/LaBrake/Crawford CH301 GAS LAWS - Day 3 CH301 Vanden Bout/LaBrake Fall 2013 Important Information HW2 POSTED - DUE TUE MORNING 9AM LM6 & 7 POSTED – DUE TUE MORNING 9AM LM2,3,4 & 5 WERE DUE THIS MORNING 9AM CH301 Vanden Bout/LaBrake Fall 2013 Unit1Day3-LaBrake Page 1
What are we going to learn today? MACROSCOPIC & MICROSCOPIC VIEWS OF GASES IDEAL GAS LAW USE IDEAL GAS LAW – IDENTIFY UNKOWN GAS CH301 Vanden Bout/LaBrake Fall 2013 QUIZ: CLICKER QUESTION 1 (points for CORRECT answer) According to Avagadro ’ s Law, a sample of H 2 gas with a volume of 10 liters, at a pressure of 2 atm, and a temperature of 25 ° C, contains ________ “ particles ” compared to a sample He gas that has a volume of 5 L at the same temperature and pressure. A. the same number of B. two times more C. four times more D. two times less E. four times less CH301 Vanden Bout/LaBrake Fall 2013 QUIZ: CLICKER QUESTION 2 (points for CORRECT answer) Which of the following is a plot of the pressure of a gas as a function of the volume at fixed temperature? B A Unit1Day3-LaBrake Page 2
function of the volume at fixed temperature? B A C D CH301 Vanden Bout/LaBrake Fal 2013 Describe a Gas PHYSICAL DESCRIPTION: VOLUME PRESSURE – most abstract property TEMPERATURE AMOUNT GAS LAWs QUANTIFY THE RELATIONSHIP OF THE PROPERTIES. EQUATION FORM OF LAWs GIVE ABILITY TO PREDICT CONDITIONS AT NEW STATE CH301 Vanden Bout/LaBrake Fall 2013 Unit1Day3-LaBrake Page 3
POLL: CLICKER QUESTION 3 You have a sample of O 2 gas T = 10 ° C and a P = 1 atm. If you increase T = 20 ° C and keep P = 1 atm, V will: A. stay the same B. be slightly higher but not double the original C. double compared to the original volume D. decrease slightly but not in half the original E. decrease to half the original volume CH302 Vanden Bout/LaBrake Spring 2012 TRY IT - Balloon in ice water… balloon in liquid N 2 CH301 Vanden Bout/LaBrake Fall 2013 COMPARE COLD BALLOON TO BALLOON IN VACUUM Unit1Day3-LaBrake Page 4
COMPARE COLD BALLOON TO BALLOON IN VACUUM COMPARE MACROSCOPIC VIEW WITH MICROSCOPIC VIEW http://ch301.cm.utexas.edu/simulations/gas-laws/GasLawSimulator.swf CH301 Vanden Bout/LaBrake Fall 2013 POLLING: CLICKER QUESTION 4 Think back to the syringe investigation: When the VOLUME of the container is DECREASED, and the T and amount of gas remains the same, the PRESSURE: a)PRESSURE INCREASES b)PRESSURE DOES NOT CHANGE c)PRESSURE DECREASES d)PRESSURE WILL CHANGE BRIEFLY, BUT THEN RETURNS TO ORIGINAL PRESSURE CH301 Vanden Bout/LaBrake Fall 2013 POLLING: CLICKER QUESTION 5 Think back to the syringe investigation: When the VOLUME of the container is DECREASED, and the T and amount of gas remains the same, the PRESSURE INCREASES. The small particle explanation is because the: Unit1Day3-LaBrake Page 5 a)# of collisions INCREASES
Think back to the syringe investigation: When the VOLUME of the container is DECREASED, and the T and amount of gas remains the same, the PRESSURE INCREASES. The small particle explanation is because the: a)# of collisions INCREASES b)# of collisions DOES NOT CHANGE c)# of collisions DECREASES d)Avg speed of particles DECREASES e)Avg speed of particles DOES NOT CHANGE CH301 Vanden Bout/LaBrake Fall 2013 POLLING: CLICKER QUESTION 6 Think back to the balloon in liquid N 2 demonstration : When the TEMPERATURE of the container is DECREASED, and the P and amount of gas remains the same, the : a)VOLUME INCREASES b)VOLUME DOES NOT CHANGE c)VOLUME DECREASES d)VOLUME WILL CHANGE BRIEFLY, BUT THEN RETURNS TO ORIGINAL VOLUME CH301 Vanden Bout/LaBrake Fall 2013 Unit1Day3-LaBrake Page 6
POLLING: CLICKER QUESTION 7 Think back to the balloon in liquid N 2 demonstration : When the TEMPERATURE of the container is DECREASED, and the P and amount of gas remains the same, THE VOLUME DECREASES - the small gas particle explanation is because the: a)AVG SPEED OF PARTICLES DECREASES b)AVG SPEED OF PARTICLES INCREASES c)AVG SPEED OF PARTICLES DOES NOT CHANGE CH301 Vanden Bout/LaBrake Fall 2013 MACROSCOPIC DESCRIPTION MICROSCOPIC MODEL (SMALL PARTICLE MODEL) EMPERICALLY DERIVED MODELS CH301 Vanden Bout/LaBrake Fall 2013 COMBINE GAS LAWS – IDEAL GAS LAW PV = nRT The value of R depends on the units of Unit1Day3-LaBrake Page 7 08205746 L atm K −1 mol −1 −1 mol −1 R = .08314472 L bar
COMBINE GAS LAWS – IDEAL GAS LAW PV = nRT The value of R depends on the units of measure used for the State Functions R = . 08205746 L atm K −1 mol −1 R = .08314472 L bar K −1 mol −1 CH302 Vanden Bout/LaBrake Spring 2012 COMBINE GAS LAWS – IDEAL GAS EQUATION THIS IS ACTUALLY QUITE COOL PV = nRT CH301 Vanden Bout/LaBrake Fall 2013 USEFULLNESS? PV = nRT Given 3 properties of the state, calculate the 4 th . Predicts every single gas should have the same number density. Same P, T should be identical – moles per volume (# density). Molar volume – volume per one mole useful for gas stoichiometry. Particles have different masses, different gases should have different mass densities under same conditions. Unit1Day3-LaBrake Page 8 – –
Given 3 properties of the state, calculate the 4 th . Predicts every single gas should have the same number density. Same P, T should be identical – moles per volume (# density). Molar volume – volume per one mole useful for gas stoichiometry. Particles have different masses, different gases should have different mass densities under same conditions. Given P, T and molar mass – calculate mass density of a gas. Given P, T and density – calculate the molar mass of a gas. CH301 Vanden Bout/LaBrake Fall 2013 POLLING: CLICKER QUESTION 9 Which balloon has the higher mass density? A. Ar B. He C. they are the same CH301 Vanden Bout/LaBrake Fall 2013 Unit1Day3-LaBrake Page 9
POLLING: CLICKER QUESTION 9 Which balloon has the higher number density? A. Ar B. He C. they are the same CH301 Vanden Bout/LaBrake Fall 2013 POLLING: CLICKER QUESTION 10 We have two identical containers held at the same T, one contains Ar, one contains He. The containers have the same mass density. Which has the higher pressure? A. Ar B. He C. they are the same CH301 Vanden Bout/LaBrake Fall 2013 Unit1Day3-LaBrake Page 10
GROUP WORK Starting with the ideal gas law and the molar mass of a gas, derive an equation for the mass density of a gas. CH301 Vanden Bout/LaBrake Fall 2013 CH302 Vanden Bout/LaBrake Spring 2012 GROUP WORK The oil produced from eucalyptus leaves contains the volatile organic compound eucalyptol. At 190 ºC and 60.0 Torr, a sample of eucalyptol vapor had a density of 0.320 g*L -1 . Unit1Day3-LaBrake Page 11 Calculate the molar mass of eucalyptol.
The oil produced from eucalyptus leaves contains the volatile organic compound eucalyptol. At 190 ºC and 60.0 Torr, a sample of eucalyptol vapor had a density of 0.320 g*L -1 . Calculate the molar mass of eucalyptol. CH301 Vanden Bout/LaBrake Fall 2013 GROUP WORK QUIZ CLICKER QUESTION The oil produced from eucalyptus leaves contains the volatile organic compound eucalyptol. At 190 ºC and 60.0 Torr, a sample of eucalyptol vapor had a density of 0.320 g*L -1 . Calculate the molar mass of eucalyptol.. a)63 g/mol b)154 g/mol c)0.01 g/mol d)10 g/mol CH301 Vanden Bout/LaBrake Fall 2013 GROUP WORK QUIZ CLICKER QUESTION Calculate the volume of carbon dioxide, adjusted to 25 ºC and 1.0 atm , that plants need to make 1.00 g of glucose. 6CO 2 (g) + 6H 2 O (l) C 6 H 12 O 6 (s)+ 6O 2 (g) Unit1Day3-LaBrake Page 12
6CO 2 (g) + 6H 2 O (l) C 6 H 12 O 6 (s)+ 6O 2 (g) CH301 Vanden Bout/LaBrake Fall 2013 What did we learn today? IDEAL GAS LAW and IDEAL GAS EQUATION CONCEPT OF NUMBER DENSITY vs MASS DENSITY DERIVED EQUATION FOR RELATIONSHIP BETWEEN MASS DENSITY AND THE MOLAR MASS OF A GAS Anything Else? Please Share…. CH301 Vanden Bout/LaBrake Fall 2013 Unit1Day3-LaBrake Page 13
DAY 3 LEARNING OUTCOMES Perform calculations using the ideal gas equation Explain the relationship between the number density and the mass density for a given gas Use the ideal gas law to determine MW of a gas Apply the concept of the gas laws to gas phase reactions and perform stoichiometric calculations Using the gas properties, masses, moles, limiting reagents and percent yields CH301 Vanden Bout/LaBrake Fall 2013 Unit1Day3-LaBrake Page 14
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