DO NOW Sketch a graph of temperature vs

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DO NOW: Sketch a graph of temperature vs. volume of a gas at constant

DO NOW: Sketch a graph of temperature vs. volume of a gas at constant pressure. Sketch a graph of pressure vs. volume of a gas at constant temperature.

Aim: How are pressure and temperature of a gas related? How are volume and

Aim: How are pressure and temperature of a gas related? How are volume and number of moles of a gas related?

Gay-Lussac’s Law—pressure and temperature of a gas are directly proportional when volume and number

Gay-Lussac’s Law—pressure and temperature of a gas are directly proportional when volume and number of moles are held constant • Formula: P 1 = P 2 T 1 T 2

The pressure exerted by a gas in an immovable piston at 273 K is

The pressure exerted by a gas in an immovable piston at 273 K is 99. 7 k. Pa. What will be the pressure of this gas when the temperature is decreased to 200. K?

• P 1 = P 2 T 1 T 2 P 1=99. 7

• P 1 = P 2 T 1 T 2 P 1=99. 7 k. Pa P 2=? T 1=273 K T 2=200. K 99. 7 k. Pa = P 2 273 K 200. K P 2=73. 0 k. Pa

The pressure exerted by a gas is 9. 4 atm. After the temperature is

The pressure exerted by a gas is 9. 4 atm. After the temperature is increased to 77 C, the pressure of the gas is 15. 2 atm. What is the initial temperature of this system?

• P 1 = P 2 T 1 T 2 P 1=9. 4

• P 1 = P 2 T 1 T 2 P 1=9. 4 atm T 1=? P 2=15. 2 atm T 2=350. K 9. 4 atm = 15. 2 atm T 1 350. K T 1=220 K

Avogadro’s Law—equal volumes of all gases under the same conditions of temperature and pressure

Avogadro’s Law—equal volumes of all gases under the same conditions of temperature and pressure have equal number of molecules. • Formula: V 1 = n 1 V 2 n 2

Don’t Forget… • 1 mol of a gas at STP occupies 22. 4 L.

Don’t Forget… • 1 mol of a gas at STP occupies 22. 4 L. • STP = 273 K, 1 atm

A sample of Ar occupies 67. 2 L at STP. How many moles of

A sample of Ar occupies 67. 2 L at STP. How many moles of the gas are present? • V 1 = n 1 V 1=22. 4 L V 2=67. 2 L n 2=3 mol V 2 n 1=1 mol n 2=?

If 2. 55 mol of He gas occupies a volume of 59. 5 L

If 2. 55 mol of He gas occupies a volume of 59. 5 L at a particular temperature and pressure, what volume does 7. 83 mol of He occupy under the same conditions?

• V 1 = n 1 V 2 n 2 V 1=59. 5

• V 1 = n 1 V 2 n 2 V 1=59. 5 L V 2=? 59. 5 L = 2. 55 mol V 2=183 L n 1=2. 55 mol n 2=7. 83 mol V 2 7. 83 mol

• Equal volumes of SO 2 (g) and O 2 (g) at STP

• Equal volumes of SO 2 (g) and O 2 (g) at STP contain the same number of 1. atoms 2. molecules 3. electrons 4. protons

• A sample of oxygen gas is sealed in container X. A sample

• A sample of oxygen gas is sealed in container X. A sample of hydrogen gas is sealed in container Z. Both samples have the same volume, temperature, and pressure. Which statement is true? 1. Container X contains more gas molecules than container Z. 2. Container X contains fewer gas molecules than container Z. 3. Containers X and Z both contain the same number of gas molecules. 4. Containers X and Z both contain the same mass of gas.