To Do… http://chem.illinois.edu Slides on the website (after each

lecture) Discussion tomorrow. Look at

final two problems. Lon-Capa (HW3 Type 1 due

Monday, February 10 by 7 pm).1

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. 2

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

3

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 larger balloon has a significantly greater pressure.

b) The smaller balloon has a significantly greater pressure.

c) The balloons have essentially the same pressure.

4

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 larger balloon has a significantly greater pressure.

b) The smaller balloon has a significantly greater pressure.

c) The balloons have essentially the same pressure (and it is equal to room pressure).

5

Clicker Question

As the number of moles of carbon dioxide increases, the pressure in the bag will

A) increase B) decrease C) stay the same

6

Clicker Question

As the pressure inside the chamber decreases, the volume of the balloon will

A) increase B) decreaseC) stay the same

7

Clicker Question

As the temperature of the gas inside the balloon decreases, the volume will

A) increase B) decrease C) stay the same

8

Clicker Question

As the temperature of the gas inside the flask increases, the pressure will

A) increase B) decrease C) stay the same

9

Clicker Question

Which of the following best represents the relationship between volume and moles of gas at constant pressure and temperature?

10

Clicker Question

Which of the following best represents the relationship between volume and moles of gas at constant pressure and temperature? [a]

11

Clicker Question

Which of the following best represents the relationship between pressure and volume of gas at constant moles and temperature?

12

Clicker Question

Which of the following best represents the relationship between pressure and volume of gas at constant moles and temperature? [d]

13

P vs. V (constant n, T)

14

PV/nT for Different Gases

(all at 1 atm and 273K)

O2: 0.08204 Latm/molKN2: 0.08206 Latm/molKH2: 0.08217 Latm/molKHe: 0.08212 Latm/molKAr: 0.08204 Latm/molK

15