Exam #1 High score: 58/60 Average: 34/60 Exam worth 35/3 = 11.67% of final grade For 90% range: If 90% on exam I, still need 90% average If 70% on exam I, need 92% average

Office Hours 367J Noyes Lab decoste@illinois.edu 3-4pm Tuesdays and Thursdays (after lecture) By appointment; open-door policy

To do 4th HW assignment due Friday, 2/26, 10 pm. It is open now. 3rd Quiz Wednesday, 3/2 in Discussion. Read Chapter 5 and do text HW. Read Chapter 6.1-6.2 and do text HW for next Thursday.

Studying Gases Good way to study the process of science. Distinguish between laws (what) and theories (why). Make observations. Use observations to develop theories. Make more observations. Continue.

Gases – Macroscopic Observations Gases take up the volume of the container. 1 cup of helium? Compressible Gases mix well (diffusion). We can smell ammonia, vinegar, etc. Gases exert pressure. Basketballs, bike tires, etc. Explosions Density of gases changes greatly with temperature.

Clicker Question You are holding two balloons filled with air – a large balloon and a small balloon. What can be said about the relative pressure of air in each balloon? a) The pressure in the larger balloon is greater because there are more moles of gas. b) The pressure in the smaller balloon is greater because there is less space inside the balloon. c) The balloons have essentially the same pressure.

V and n (KMT)

V and T (KMT) .

V vs. T(°C) (constant P, n)

V vs. T(K) (constant P, n)

P and V (KMT)

P vs. V (constant n, T)

PV/nT for Different Gases (all at 1 atm and 273K) O2: 0.082040 Latm/molK N2: 0.082059 Latm/molK CO2: 0.081538 Latm/molK NH3: 0.080875 Latm/molK Ar: 0.082040 Latm/molK