2. 1 Chemistry 111 Chapter 13

3. 2 Gases Revisited Ideal Gas Law Gas Density

4. 3 Ideal Gas Law Boyle’s Law: P V = k Charles’ Law: P = k T Avogadro’s Law: P = n k All Together now: P V = n k T However, we change k to R R

5. 4 R – The Gas Constant It turns out that the Ideal Gas Law (PV=nRT) always has the same constant: If you change units, R changes. –but we never bother to change units.

6. 5 Gas Density D=mass / Volume –Mass = moles  MM = n  MM –MM is molecular mass By fooling with PV=nRT we can get:

7. 6 Gas Density Mass of 1.000 mol CO 2 : –(1.000 mol)  (44.01 g/mol) = 44.01 g CO 2 What is the density of CO 2 on a normal day? –P = 1.00 atm, T = 298 K Note: this is ~2000  lower than water!

8. 7 Team Work Time Chapter 13 – Gases –Spend time discussing the ideal gas lab & working some problems. –(Textbook discussion problems) Use class time to discuss how to solve these: –7, 10, 25

9. 8 Gas Stoichiometry Stoichiometry Map Gas Stoichiometry –At STP –With PV=nRT

10. 9 Moles of B Moles of A  Molar Mass Gas Laws  Avogadro’s Number  Molarity  Molar Mass Gas Laws  Avogadro’s Number  Molarity Mass of B Volume of Gas B Number of particles of B Volume of Solution B Mass of A Volume of Gas A Number of particles of A Volume of Solution A Moles B Moles A Stoichiometry Map - Gases

11. 10 Gas Stoichiometry at STP STP = Standard Temperature, Pressure = 273.15 K, 1 atm 1 mol of gas at STP: –P = 1 atm –V = ? –n = 1 mol –R = 0.08206 L atm mol -1 K -1 –T = 273.15 K This is a conversion factor: –Use it @ STP.

12. 11 Homework Problems Chapter 13 – Gases Use class time to discuss how to solve these: –16, 19, 20 Turn in these: –16, 17, 19, 20

13. 12 Exam Results Raw: –Average = 72.3 –Median = 75.0 –Max = 100.0 Curve: –Set median = 78, max=100 –y=mx+b =(0.88)x+12.0 –(only if it improved your score)