Ideal Gas Law PPT

8/13/2019 Ideal Gas Law PPT

1/25

Ideal Gas Law

PV=nRT


2/25

Remember

Boyles Law

Charles Law:

Combined Gas Law:(Units MUST Match

Temp in Kelvin!!!)

2

2

1

1

T

V

T

V

2

22

1

11

T

VP

T

VP

2211 VPVP


3/25

A gas with a volume of 350 ml is collected

at 15o C and 120 kPa. If the temperature

changes to 30o

C, what pressure would berequired to put this gas in a 300 ml

container?

K

mlP

K

mlkPa

303

300

288

350120 2

kPaP 3.1472


4/25

A balloon has a volume of 500 ml at a

temperature of 22oC and a pressure of 755

mmHg. If the balloon is cooled to 0o

C anda pressure of 145 mmHg, what is its new

volume?

ml

V3.2409

2

K

VmmHg

K

mlmmHg

273

145

295

500755 2


5/25

Avogadros Principle

Under similar conditions (same Temp and

Pressure) equal volumes of gases contain

equal numbers of particles.

10 L of H2(g) and 10 L of O2(g)

Both at Standard Temperature and

Pressure (STP) contain

The same number of particles!


6/25

Molar Volume

The volume of 1 mole of gas particlesat STP

is 22.4 L


7/25

Ideal Gas Law Animation:
http://www.marymount.k12.ny.us/marynet/06stwbwrk/06gas/2lpimavogdro/2lpimavogadro.htmlhttp://www.marymount.k12.ny.us/marynet/06stwbwrk/06gas/2lpimavogdro/2lpimavogadro.html


8/25

Try this:

1 mole of gas occupies 22.4 L at STP

= __________ ml

(22400)= ___________ moles of gas

(1 mole)

= ___________ particles(6.02 x 1023)


9/25

How many particles in 11.2 dm3of gas at STP?

0.5 moles = 3.01 x 1023particles

22,400 cm3 of NH3gas at STP weighs?

= 22.4 L = 1 mole = 17 grams (add up MW)44.8 L of NH3at STP weighs?

= 2 moles = 34 grams

_____ grams = 1 mole of nitrogen gas

= _____ L at STP?

mole

L

L

4.22

8.44

28.00

22.4


10/25

How many N2molecules are

in 22.4 dm3 at STP?

= 1 mole = 6.02 x 1023

What volume will 1.2 x 1024H2 molecules

occupy at STP?

= 2 moles = 44.8 L at STP


11/25

Ideal Gas Equation

Use when NOTat STP!!!

PV= nRTP = Pressure (in kPa)

V = Volume (in Liters or dm3)n = number of moles

T = Temperature (in Kelvin)

R =8.31 L kPa

mole K


12/25

Development of R in

Kmole

LkPa

Kmole

LkPa

nT

PVR

31.82731

4.223.101

Kmole

LkPa


13/25

1. What volume will 2 moles of NO2occupyat 300 Kelvin and 90 kPa?

LV

KmolesVkPa

nRTPV

4.5590

30031.82

30031.8290


14/25

What will be the temp of 2 grams of

H2if 5000 cm3is at 5 atm?

KT

TmoleLkPa

nRTPV

8.30431.81

55.506

31.8155.506


15/25

Finding Molecular Weight of a Gas

Remember: MW = grams / moles

Converting grams to moles

Divide grams by the molecular weight


16/25

1) 5.0 L of a gas weighs 30.00 g at 20o C &

92 kPa. What is the mole weight of the gas?

g/mol581mol0.19

g30.00MW

PV=nRT

92kPa 5.0 L= n 8.31 293 K

n = 0.19 mol

mol?

g30.00

moles

gramsMW


17/25

2)If the mole weight of a gas is 26 g/mol and

18.00 g of the gas is 30 L at 21oC, what is the

pressure of the gas?

PV= nRT

P x 30 L=0.69 mol x 8.31 x 294 K

P = 56.2kPa

mol0.69

g/mol26

g18.00

MW

gn


18/25

Stoichiometry

Solving Steps.

Balance the Equation

Change grams to moles

Use mole ratio to solve

Change moles to volumes


19/25

Use mole ratio

(coefficients)

Use 22.4 L/mol

@ STPOr PV = nRT

Use MWon P.T.

Use MWon P.T.

Use 22.4 L/mol

@ STPOr PV = nRT


20/25

Mg (c) + HCl (ag)MgCl2+ H2(g)

If 2.43 g Mg react what volume of H2isproduced? (at STP)


2.43 g Mg

0.1 mole

mol

gg

3.24

43.2

1:1

molesmol

L 1.04.22

0.1 moles

2

2.24 L H2

? L


21/25

)313)(31.8)(1.0())(85( KmolVkPa

nRTPV

Mg (c) +2HCl (ag)MgCl2+ H2(g)

If 2.43 g Mg react what volume of H2is produced at

40oC and 85 kPa?


2.43 g Mg

0.1 mole

mol

gg

3.24

43.2

1:10.1 moles

2

3.06 L H2? L


22/25

If 250 ml of H2is produced at 20oC &

100 kPa, what mass of Mg reacted?

KnLkPa 29331.825.0100

2H01.0 molesn

Mg (c) + HCl (ag)MgCl2+ H2(g)2

? g 250 ml

nRTPV

0.01 moles0.01 mole1:1

0.243 g Mg

molesmol

g01.03.24


23/25

Volume to Volume

THE MOLE RATIO IS THE SAME ASTHE VOLUME RATIO.

Liters BUse mole ratio

(coefficients)Liters A

B i f th


24/25

Burning of methane:

What vol. of oxygen is needed to completely

burn 1 L of methane?

CH4+ O2 CO2(g) + H2O (l)

2.0 L1:2

1.0 L

2 2

B i f th


25/25

Burning of methane:

To produce 11.2 L of CO2requires how

many moles of O2

at STP?

CH4+ O2 CO2(g) + H2O (l)

22.4 L 2:1 11.2 L1 mole =

2 2

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Ideal Gas Law PPT