CHEM1100 Lecture Notes - Lecture 13: Ideal Gas, Gas Constant, International System Of Units

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blueclam798

25 May 2018

School

Department

Chemistry

Course

CHEM1100

Professor

Gwen Lawrie

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Lecture 13 - kinetic gas theory !

Characteristics of a gas

•a gas will expand to occupy all available space it is in and will not form a seperate

surface

•Gases have no ﬁxed volume or shape

•Atoms in a gas move independently of each other and move randomly

•Gas exerts a pressure

Gas pressure

•particles in constant motion collide with each other and the surrounding walls

•Pressure: force / area force is applied

Units of pressure !

Standard temperature and pressure !

STP is 273.15 K (00C) and 1 bar

Absolute temperature

0 K = -273.15 0 C

Ideal gas laws

*laws that describe the properties of ideal gases !

SI units of pressure = N m -2

1 Pa = N m -2

1 atm = 1.01325 x 105 Pa

1 torr = 1/760 atm

1 bar = 1 x 105 Pa

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Document Summary

Gas pressure: particles in constant motion collide with each other and the surrounding walls, pressure: force / area force is applied. Si units of pressure = n m -2. Stp is 273. 15 k (00c) and 1 bar. * laws that describe the properties of ideal gases. Volume is proportional to the amount of gas. Describes how an ideal gas performs under given conditions of pressure, volume and temperature. The total pressure of a mixture of gases is the sum of the pressures that each gas would exert if it were alone in the container. This theory assumes that the the identity of the gas does not make a di erence to the pressure (only the number of gas molecules) - it assumes that all the molecules are ideal gases. Where pi = partial pressure of that gas. Xi = the mole fraction of that gas. P = the total pressure of the mixture of gases.

Related Questions

Converting between Units of Pressure Gases are different from solids and liquids. In a sample of gas, the molecules are far apart. The gas molecules also move around and collide with each other as well as with the walls of the container. These collisions generate pressure. The pressure of a gas can be measured in different units. One convenient unit of measure is called the atmosphere (atm) because it is based on atmospheric pressure. At sea level, the average pressure is 1 atm. As you get higher in altitude, the pressure steadily drops until you leave the atmosphere, where the pressure is very close to 0 atm. The table below shows the different commonly used units of measuring gas pressure. Use this table in the pressure unit conversions. Unit Abbreviation 1 atm equivalent atmosphere atm 1.00 atm (exact) millimeters of mercury mmHg 760 mmHg torr torr 760 torr inches of mercury in.Hg 29.9 in.Hg pounds per square inch (psi) lb/in.2 14.7 lb/in.2 pascal Pa 101,325 Pa.

Part C

High-pressure liquid chromatography (HPLC) is a method used in chemistry and biochemistry to purify chemical substances. The pressures used in this procedure range from around 500 kilopascals (500,000 Pa) to about 60,000 kPa (60,000,000 Pa). It is often convenient to know the pressure in torr. If an HPLC procedure is running at a pressure of 5.81Ã10⁸ Pa , what is its running pressure in torr?

Express the pressure numerically in torr.

Boyles Law

a) A10.0 L sample of a gas at 25oC and 1.5 atm iscompressed at constant temperature to a volume of 1.0 L. What isthe new pressure?

b) A3.5 L sample of a gas at 1.0 atm is expanded at constanttemperature until the pressure is 0.10atm. What is the volume of the gas?

Charless Law

a) A2.5 L sample of gas at 25oC is heated to50oC at constant pressure. What is the finalvolume?

b) Whattemperature would be required to increase the volume from 2.5 L to6.0 L?

Avogadros Law

a) Assumingno change in temperature and pressure, how many moles of methane(CH₄) need to be added to 0.50 moles of methane todouble the volume?

b) 50g of solid carbon dioxide evaporates to carbon dioxide gas atstandard temperature and pressure. What isthe volume of carbon dioxide gas?

Combined Gas Laws

Calculate the temperature when a 0.50 L sample of gas at 1.0 atmand 25oC is compressed to 0.05 L of gas at 5.0atm.

Ideal Gas Law

a) Whatis the volume of gas occupied by 10.0 g CH4 at37oC and 4 atm?

b) Whatis the mass of N2 required to occupy 5.0 L at80oC and 560 mmHg?

Molar Density of Gases

a) Whatis the density of He at STP?

b) Whatis the density of carbon dioxide at 120^oC and 1.5atm?

Application of Gas Laws:

a) How many grams ofNO₂, nitrogen dioxide, are contained in 0.500 L of thegas at STP?

b) Calculate thedensity of NO₂ gas, in grams per liter, at 110C and 12atm.

c) Calculate the molarmass of a gas if 0.125 g of the gas occupies 93.3 mL at STP.

d) On a spring morning(15C) you fill your tires to a pressure of 2.25 atmospheres. As youride along, the tire heats up to 45C from the friction on the road.What is the pressure in your tires now?

e) What volume ofH₂ is formed at STP when 6.0 g of Al is treated withexcess NaOH?

2NaOH+ 2Al + 6H₂O 2NaAl(OH)₄ +3H₂(g)

Application of Gas Law

a) Whatis the effect on the volume of an ideal gas when the temperature isdecreased from 700K to 350K at constant pressure?

b) Whatis the effect on the volume of an ideal gas when both the pressureand temperature are reduced by half?

c) Whatis the effect on the volume of an ideal gas when the pressure ischanged from 722 torr to 0.950 atm, and the temperature is changedfrom 5^oC to 273 K?

Stoichiometric Relationships

a) Howmany grams of phosphorus react with 35.5 L of O₂ at STPto form tetraphosphorus oxide, according to the following reactionequation?

P₄ (s) + 5 O₂ (g)P₄O₁₀ (s)

b) Ammonia decomposes to nitrogen and hydrogen when in thepresence of heated steel wool. What is thefinal volume of the gas when 45 g of ammonia decomposes at150^oC and 1 atm pressure. Writea balanced equation before you start your calculations!

Daltons Law of Partial Pressures

a) A sample of a natural gas contains 8.24 moles of methane(CH₄), 0.421 mole of ethane(C₂H₆), and 0.116 mole of propane(C₃H₈). If the totalpressure of the gases is 1.37 atm, what are the partial pressuresof the gases?

b) Earths atmosphere consist of 78% N₂and 20%O₂, and other gases. What is the partial pressure ofN₂ and O₂intorr, when the atmospheric pressure is 1 atm?

c) Ammonia is completely decomposed to nitrogen and hydrogen, asin question 9b). At the end of theexperiment the pressure of the gas mixture is 866mmHg. Calculate the partial pressures ofN₂ and H₂.

CHEM1100 Lecture Notes - Lecture 13: Ideal Gas, Gas Constant, International System Of Units

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