Ideal Gas Law

1
Ideal Gas Law
PV nRT
Brings together gas properties.
Can be derived from experiment and theory.
2
Ideal Gas Equation
Universal Gas Constant
Volume
P V n R T
Pressure
Temperature
No. of moles
R 0.0821 atm L / mol K R 8.314 kPa L / mol
K
Kelter, Carr, Scott, Chemistry A Wolrd of Choices
1999, page 366
3
PV nRT
Standard Temperature and Pressure (STP) T
0 oC or 273 K P 1 atm 101.3 kPa
760 mm Hg
P pressure V volume T temperature
(Kelvin) n number of moles R gas constant
1 mol 22.4 L _at_ STP
Solve for constant (R) PV nT
Recall 1 atm 101.3 kPa
Substitute values (1 atm) (22.4 L) (1
mole)(273 K)
(101.3 kPa)
R 0.0821 atm L mol K
R
8.31 kPa L mol K
( 1 atm)
R 0.0821 atm L / mol K or
R 8.31 kPa L / mol K
4
Ideal Gas Law
What is the volume that 500 g of iodine will
occupy under the conditions Temp 300oC and
Pressure 740 mm Hg?
Step 1) Write down given information. mass
500 g iodine T 300oC P 740 mm
Hg R 0.0821 atm . L / mol . K
Step 2) Equation
PV nRT
Step 3) Solve for variable
Step 4) Substitute in numbers and solve
V
What MISTAKES did we make in this problem?
5
What mistakes did we make in this problem?
What is the volume that 500 g of iodine will
occupy under the conditions Temp 300oC and
Pressure 740 mm Hg?
Step 1) Write down given information. mass
500 g iodine ? Convert mass to
gram recall iodine is diatomic (I2) x
mol I2 500 g I2(1mol I2 / 254 g I2) n 1.9685
mol I2 T 300oC ?Temperature must be
converted to Kelvin T 300oC 273 T 573
K P 740 mm Hg ?Pressure needs to have
same unit as R therefore, convert pressure
from mm Hg to atm. x atm 740 mm Hg (1 atm /
760 mm Hg) P 0.8 atm R 0.0821 atm .
L / mol . K
6
Ideal Gas Law
What is the volume that 500 g of iodine will
occupy under the conditions Temp 300oC and
Pressure 740 mm Hg?
Step 1) Write down given information. mass
500 g iodine n 1.9685 mol I2 T 573
K (300oC) P 0.9737 atm (740 mm Hg)
R 0.0821 atm . L / mol . K V ? L
Step 2) Equation PV nRT
Step 3) Solve for variable
Step 4) Substitute in numbers and solve
V 95.1 L I2
7
Ideal Gas Law
What is the volume that 500 g of iodine will
occupy under the conditions Temp 300oC and
Pressure 740 mm Hg?
Step 1) Write down given information. mass
500 g iodine T 300oC P 740 mm
Hg R 0.0821 atm . L / mol . K
Step 2) Equation
PV nRT
Step 3) Solve for variable
Step 4) Substitute in numbers and solve
V
What MISTAKES did we make in this problem?
8
Ideal Gas Law
        Ideal Gas Law
        Ideal Gas Law
Keys
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