Warm-up 6-1 Convert -121°C to Kelvins (2) The graph represents a reaction Is this reaction exothermic or endothermic? (3) STP is (a) 273 ° C and 1 atm (b) 0° C and 1atm (c ) 0° C and 780 mmHg (d) 273 ° C and 101.3 kPA

Answers to Warm-up 6-1 Convert -121°C to Kelvins Answer: 152 Kelvins (2) The graph represents a reaction Is this reaction exothermic or endothermic? Answer: endothermic (3) STP is (a) 273 ° C and 1 atm (b) 0° C and 1atm (c ) 0° C and 780 mm Hg (d) 273 ° C and 101.3 kPA Answer: (b) 0° C and 1atm

Some Tips in Solving Gas Law Problems GAS LAWS Some Tips in Solving Gas Law Problems

REMEMBER: Convert.. Convert… Add 273 to Celsius All temps must be in Kelvin Convert.. Convert… Add 273 to Celsius

USE THE UNITS! Ans: Pressure Remember that the units can be used to identify given information. (1) kPA (kiloPascal) Ans: Pressure (2) L (Liter) Ans : Volume

Ans : Volume Ans : Pressure (3) K (Kelvin) Ans: Temperature (4) torr (5) Pa (Pascal) Ans : Pressure (6) mL (milliliter) Ans : Volume

Ans: Pressure (7) mm Hg (millimeter mercury) Ans : Pressure (8) atm (atmosphere) (9) cm Hg (centimeter mercury) Ans: Pressure

Ans : Pressure Ans: Temperature (10) ft3 (cubic feet) Ans : Volume (11) psi (pounds per square inch) Ans : Pressure (9) °C (Celsius) Ans: Temperature

Remember the relationships between the variables (and don’t forget the constant!)

(constant temperature) Boyle’s Law (constant temperature) Pressure Volume P1V1 = P2V2

Charles Law (constant pressure) Kelvin Volume Temperature V1T2 = V2T1

Gay-Lussac’s Law (constant volume) Kelvin Pressure Temperature P1T2 = P2T1

Combined Gas Law (no constant) P1V1T2 = P2V2T1

…Let’s see if you can recognize the gas law for each of these problems… The Celsius temperature of a 3.00 L sample of a gas was lowered from 80.0C to 30.0C. What will be the resulting volume of this gas? Charles Law

A gas in a sealed container has a pressure of 125 kPa at a temperature of 30.0C ? If the pressure in the container is increased to 201 kPa, what is the new temperature? Gay-Lussac’s law  

A sample of gas occupies a volume of 1. 35 L at 27C A sample of gas occupies a volume of 1.35 L at 27C. What temperature is required to increase the volume to 3.00L ? Charles law

A sample of helium gas has a volume of 250 mL at 740 torr pressure A sample of helium gas has a volume of 250 mL at 740 torr pressure. Find its volume at 800 torr pressure if the temperature of the helium was not changed. Boyle’s law

Neon gas occupies 2 L at 135 kPa Neon gas occupies 2 L at 135 kPa. Find the pressure that this gas will exert if its volume was lowered to 1.75 L (assuming constant temperature). Boyle’s law

At 0. 00°C and 1. 00 atm pressure, a gas has a volume of 30. 0 mL At 0.00°C and 1.00 atm pressure, a gas has a volume of 30.0 mL.If the temperature is raised to 30.0°C and the gas is transferred to a 20.0 mL container, what will be the gas pressure in the container? Combined gas law

Helium gas in a 2. 00 L sealed metal cylinder is under 1. 12 atm Helium gas in a 2.00 L sealed metal cylinder is under 1.12 atm. pressure. At 36.5C, that same gas sample has a pressure of 2.56 atm. What was the initial temperature of the gas in the cylinder? Gay – lussac’s law

A 25. 0–L sample of an ideal gas at STP is heated to 55°C at 605 torr A 25.0–L sample of an ideal gas at STP is heated to 55°C at 605 torr. What is the new volume? Combined gas law