Not so long ago, in a chemistry lab far far away… May the FORCE/area be with you

1.Describe Gay-Lussac’s Law with a formula 2.Use Gay-Lussac’s Law to determine either a temperature or volume 3.Combine all three laws into the Combined Gas Law 4.Use the Combined Gas Law to determine either temperature, volume or pressure

If n and V are constant, then P α T P and T are directly proportional.  If one temperature goes up, the pressure goes up! Joseph Louis Gay- Lussac ( )

Gay Lussac’s Law Summary The pressure and temperature of a gas are directly related, provided that the volume remains constant.

P1P1 T1T1 P2P2 T2T atm 298 K V2V2 325 K 3.27 L

P1P1 T1T1 P2P2 T2T2 1.8 atm 273 K 1.9 atm T2T2 288 K or 15.2 o C

Now let’s put all 3 laws together into one big law…….

 The good news is that you don’t have to remember all three gas laws! Since they are all related to each other, we can combine them into a single equation. BE SURE YOU KNOW THIS EQUATION! No, it’s not related to R2D2

The Combined Gas Law The combined gas law expresses the relationship between pressure, volume and temperature of a fixed amount of gas. Boyle’s law, Gay-Lussac’s law, and Charles’ law are all derived from this by holding a variable constant.

If you should only need one of the other gas laws, you can cover up the item that is constant and you will get that gas law! = P1P1 V1V1 T1T1 P2P2 V2V2 T2T2 Boyle’s Law Charles’ Law Gay-Lussac’s Law

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A sample of helium gas has a volume of L, a pressure of atm and a temperature of 29°C. What is the new temperature(°C) of the gas at a volume of 90.0 mL and a pressure of 3.20 atm? Set up Data Table P 1 = atm V 1 = 180 mL T 1 = 302 K P 2 = 3.20 atm V 2 = 90 mL T 2 = ??

 P 1 = atm V 1 = 180 mL T 1 = 302 K  P 2 = 3.20 atm V 2 = 90 mL T 2 = ?? P 1 V 1 P 2 V 2 = P 1 V 1 T 2 = P 2 V 2 T 1 T 1 T 2 T 2 = 3.20 atm x 90.0 mL x 302 K atm x mL T 2 = 604 K = 331 °C = 604 K

A gas has a volume of 675 mL at 35°C and atm pressure. What is the temperature in °C when the gas has a volume of L and a pressure of 802 mm Hg?

A balloon has a volume of 785 mL on a fall day when the temperature is 21°C. In the winter, the gas cools to 0°C. What is the new volume of the balloon?

A sample of neon gas used in a neon sign has a volume of 15 L at STP. What is the volume (L) of the neon gas at 2.0 atm and –25°C?

Hint #5. A record of data is essential. It fools the instructor into thinking that you were working.

1.Describe Gay-Lussac’s Law with a formula. 2.Use Gay-Lussac’s Law to determine either a temperature or volume 3.Combine all three laws into the Combined Gas Law 4.Use the Combined Gas Law to determine either temperature, volume or pressure

Pass the Clicker!!!

atm atm atm atm 5. Not listed

o C o C o C o C 5. Not listed

mL mL mL mL 5. Not listed

The End!!!