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Introduction to Gas Laws. Boyle’s Law Charles’ Law and Gay-Lussac’s Laws. Kelvin Temperature Scale. A temperature scale called the Kelvin scale is used when dealing with gases. This scale uses –273 o C as the zero point.
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Introduction to Gas Laws Boyle’s Law Charles’ Law and Gay-Lussac’s Laws
Kelvin Temperature Scale • A temperature scale called the Kelvin scale is used when dealing with gases. • This scale uses –273oC as the zero point. • On this scale there is a point called absolute zero that is the theoretical point when the gas would have no volume. (This does not happen!) • To convert from degrees Celsius to Kelvins: TK = ToC + 273
Boyle’s Law Pressure and Volume • This law states that at a constant temperature, as the pressure on a gas increase, the volume of the gas decreases proportionally, the volume and pressure of a gas are inversely proportional.
This law can be written as: P1V1 = P2V2 Where: P1 is the initial pressure V1 is the initial volume P2 is the final pressure V2 is the final volume Robert Boyle (1627 -1691)
Example #1: A 2.0 L party balloon at 98kPa is taken to the top of a mountain where the pressure is 75kPa. Assume the temperature is the same. What is the new volume of the balloon? P1V1= P2V2 (98 kPa)(2.0 L) = (75 kPa) V2 2.6 L = V2
Charles’ Law Volume and Temperature • This law states that the volume of a gas varies directly with its temperature in Kelvin, if the pressure and amount of gas are constant.
This law can be written as: Where: V1 is the initial volume T1 is the initial temperature V2 is the final volume T2 is the final temperature Temperature must be in Kelvin
Calculation #2: A gas inside a cylinder with a movable piston is to be heated to 315oC. The volume of gas in the cylinder is 0.30 L at 25oC. What is the final volume when the temperature is 315oC? V2= 0.59 L
This law states that the pressure of any gas is directly proportional to its Kelvin temperature. • For this law, there must be a constant volume and a fixed mass of gas.
As the temperature decreases, gas particles move more slowly and collide less frequently with each other, causing pressure to decrease. • When temperature increases, the gas particles move faster, causing more collisions and increasing the pressure.
Calculations #3: A glass vessel can only withstand a max internal pressure of 225 kPa. It is filled with a gas at 21oC and 100.0 kPa and heated. At what temperature in degrees Celcius would the vessel burst?