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# Ideal gas law

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### Ideal gas law

1. 1. IDEAL GAS LAW<br />
2. 2. QUICK REVIEW<br />Boyle’s Law: P1V1= P2V2<br />Pressure and volume are inversely proportional<br />Charles Law: V1 = V2<br />T1 T2 <br />Volume and temperature are directly proportional<br />Gay Lussac’s Law: P1 = P2<br />T1 T2 <br /> Pressure and volume are directly proportional<br />TOGETHER THE VARIABLES FORM…<br />
3. 3. The COMBINED GAS LAW<br />P1V1= P2V2<br /> T1 T2<br />** Gaining and understanding of these laws allows you to understand how gases behave when you change the pressure, volume, or temperature of a gas sample.**<br />
4. 4. GASES BEHAVE THE SAME WAY. <br />According to the Kinetic Molecular Theory, gases:<br />Consist of a large number of particles that are far apart.<br />Undergo elastic collisions, which means, no energy is lost- kinetic energy is conserved.<br />Are in continuous rapid motion.<br />Are neither attracted to or repelled by other gas particles.<br />Are dependent upon temperature for the speed of their particles.<br />
5. 5. A real gas does not completely behave according to the assumptions of this theory.<br />An ideal gas conforms to all of the the assumptions of this theory.<br />
6. 6. IDEAL GAS LAW<br />The ideal gas law assumes that all gases behave perfectly and identically to the rules of the kinetic molecular theory.<br />It shows the relationship between pressure, volume, temperature, and the amount of gas in moles.<br />It can be used to find one of the four variables given the other three.<br />
7. 7. IDEAL GAS LAW FORMULA<br />PV= nRT<br />
8. 8. P= Pressure: The force per unit are applied to the surface of an object.<br />The pressure of the air molecules in this tornado can knock down numerous trees…<br />
9. 9. V= Volume: The measurement of how much space matter takes up.<br />The volume of this air takes up enough space to fill a hot air balloon!!!<br />
10. 10. n= Amount of gas in moles<br />
11. 11. R= Gas Constant<br />.0821 atm L<br /> mol K<br />
12. 12. T= Temperature: a measure of the average kinetic energy of particles of matter.<br />Common Units of Temperature:<br />Kelvin (K): The only units that can be used when doing numerical problems with gases.<br />Celsius (°C): Must be converted to Kelvin before doing problems (add 273).<br />
13. 13. More on RRRRRRR….<br /><ul><li>“R” is the gas constant. It uses ALL of the units that are represented in the formula by other variables.</li></ul>Units in the gas constant: atm L<br /> mol K<br /><ul><li>For every problem the units of your variables have to be in the units used in the gas constant!!</li></li></ul><li>Pressure Conversions: Back to Dimensional Analysis<br />**Quick Tip: To convert from unit to unit you have to have a conversion factor.** <br />A Conversion factor relates the unit that you start with and the unit that you want to convert too.<br />
14. 14. MORE ON PRESSURE<br />Some word problems may give you pressure in a variety of ways.<br />Atmospheres (atm): The average air pressure at sea level.<br />Millimeters of Mercury(mmHg): originates from how pressure is measured with a barometer.<br />Torr: Named Italian physicist Evangelista Torricelli. The torr is exactly equal to mmHg.<br />KiloPascal(kPa): Another SI unit for pressure.<br />
15. 15. Here’s the Connection…<br />In these amounts, all of these units are EQUAL!!!<br />1 atm =760 mmHg =760 torr =101.3 kPa<br />YOU HAVE TO MEMORIZE THESE CONVERSIONS!!!<br />
16. 16. Example 1: Convert a pressure of 1.75 atmospheres to kiloPascals.<br />
17. 17. Example 2: Convert a pressure 570 torr to atmospheres.<br />
18. 18. Example: The atmospheric pressure in Denver Colorado is .830 atmospheres. What is the pressure in a) mmHg b)kPa<br />
19. 19. More Gram to Mole Conversions<br />**Quick Tip: MOLAR MASS is the only thing that can help you convert from grams to moles!!**<br />O2= _______g 64g O2= _______mol <br />HF= ________g 40g HF= ___________mol<br /> <br />CO2= __________g 88g CO2= _______mol <br />
20. 20. FREQUENTLY USED TERMS IN WORD PROBLEMS: MEMORIZE THESE!!!<br />Standard Temperature and Pressure: (STP)<br />Pressure= 1 atm<br /> Temperature= 273K or 0°C <br />Room Temperature: Kelvin scale= 298 K<br /> Celsius scale= 25°C<br />If a word problems refers to “STP” or “room temperature”, it is important for you to know these fixed values.<br />
21. 21. Ideal Gas Law Example 1: <br />A sample of gas has a volume of 10 liters,a pressure of 1.5 atm, and a temperature of 25°C, how many moles of gas do I have?<br />
22. 22. Ideal Gas Law Example 2:<br />If I have 3.5 moles of a gas at a pressure of 895 kPa with a volume of 50 liters, what is the temperature?<br />