monday february 6, 2012
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Monday February 6, 2012. ( The Ideal Gas Law). Bell Ringer Monday, 2-6-12. - PowerPoint PPT PresentationTRANSCRIPT
MondayFebruary 6, 2012
(The Ideal Gas Law)
Bell RingerMonday, 2-6-12A chemist has two identical 5.00 liter
containers. Into one of these he puts hydrogen gas and into the other he puts nitrogen gas. He brings both containers to 40oC and establishes
pressures of 2.00 atm in each. If the chemist put 6.00 moles of hydrogen gas into one of the containers, how
much nitrogen gas did he put into the other container?… by what law?6.00
molesAvogadro’s
Law
Assignment Currently Open
Summative or Formative
Date Issued
Date Due
Date Into Grade Book
Last Day
WS: Stoichiometry – Mole to Mole Conversions F3 1/6 1/10
WS: Chart It! Think-Pair-Share (Part 1) F4 1/9 1/11
WS: Chart It! Think-Pair-Share (Part 2)F5 1/10 1/12
The Mathematics of Combustion Reactions
OR
The Mathematics of CO2 Scrubbers
F7 1/12 1/19
QUIZ – LIMITING REACTANT & PERCENT YIELD S2 1/20 1/20 1/24 2/7
Activity – Stoichiometry, Limiting Reactant, and Percent Yield – Putting It
All Together1/23 1/24
WS – Introduction to Gases 1/24 1/26
Bell Ringers 1/23 thru 1/27 F 1/23 1/27
QUIZ – THE NATURE OF GASES S 1/27 1/27 1/27 2/10
WS - Pressure F 1/30 2/1
WS – Boyle’s Law F 1/31 2/2
WS - Charles’ Law F 2/1 2/3
WS – Dalton’s and Avogadro’s Laws F 2/2 2/6
QUIZ – WORKING WITH GASES S 2/3 2/3 2/6 2/17
Announcements
I will be available this afternoon after school
until 4:45.
The Ideal Gas Law
• Remember, there are three quantities that are needed to describe a gas sample:–Pressure–Volume–Temperature
• A gas sample can be further characterized using a fourth quantity:
–the number of moles of the gas.
The Ideal Gas Law• The number of molecules or moles
present will always affect at least one of the other three quantities.– Ex) If the number of molecules is increased
for a sample at constant volume and temperature, the collision rate increases, therefore, the pressure increases.
– Ex) If the pressure and temperature were kept constant while the number of molecules increased, the volume would increase.
• Gas pressure, volume, temperature, and the number of moles are all interrelated.
The Ideal Gas Law
• There is a mathematical relationship that describes the behavior of a gas sample for any combination of these conditions:• The ideal gas law is the mathematical relationship among pressure, volume, temperature and the number of moles of a gas.
The Ideal Gas Law
V = nRT/Por
PV = nRTV = volumeN = moles
T = temperatureP = pressure
R = the ideal gas constant
The Ideal Gas Constant
• In the equation representing the ideal gas law, the constant R is known as the ideal gas constant.
• Its value depends on the units chosen for pressure, volume, and temperature.
• The volume of one mole of an ideal gas at STP (1 atm and 273.15 K) is 22.414 10 L. - use this value in ideal gas law calculations when the volume is in liters, the pressure is in atmospheres, and the temperature is in kelvins.
• See Table 11-1 (next slide) for the value of R when other units for n,P,V, and T are used:
The Ideal Gas Constant
The Ideal Gas Constant• The ideal gas law can be applied to
determine the existing conditions of a gas sample when three of the four variables, P,V,T, and n, are known.
• It can also be used to calculate the molar mass or density of a gas sample.
• Be sure to match the units of the known quantities and the units of R.
• You will be using R = 0.0821 L•atm/(mol•K).
The Ideal Gas Constant
• Your first step in solving any ideal gas law problem should be to check the known values to be sure you are working with the correct units.• If necessary, you must convert
volumes to liters, pressures to atmospheres, temperatures to kelvins, and masses to numbers of moles before using the ideal gas law.
Sample Problem• What is the pressure in atmospheres exerted by a 0.500 mol
sample of nitrogen gas in a 10.0 L container at 298 K?Given: V of N2 = 10.0 L
n of N2 = 0.500 molT of N2 = 298 K
Unknown: P of N2 in atm
PV = nRTP = nRT/V
P = (0.500 mol)(0.0821 Latm/molK)(298 K)/10.0 L
P = 1.22 atm
The Ideal Gas Constant
Sample Problem• What is the volume, in liters, of 0.250 mol of oxygen
gas at 20.0°C and 0.974 atm pressure?Given: P of O2 = 0.974 atm
n of O2 = 0.250 mol
T of O2 = 20.0°C + 273.2 = 293.2 K
Unknown: V of O2 in L
V = nRT/PV = (0.250 mol O2)(0.0821 Latm/molK)(293.2K)/0.974 atm
V = 6.17 L O2
The Ideal Gas Constant
Sample Problem• What mass of chlorine gas, Cl2, in grams, is contained in a
10.0 L tank at 27°C and 3.50 atm of pressure?Given: P of Cl2 = 3.50 atm
V of Cl2 = 10.0 L
T of Cl2 = 27°C + 273.2 = 300 KUnknown: mass of Cl2 in grams
PV = nRTn = PV/RT
n = (3.50 atm)(10.0 L Cl2)/(0.0821 Latm/molK)(300 K)
n = 1.42 mol Cl2Mass of Cl2 = 1.42 mol x 70.90 g/mol = 101
g Cl2
The Ideal Gas Constant
The Ideal Gas Law
Worksheet