Robert Boyle Irish Chemist work done with a Jtube...Oct 14, 2019 · If we add an additional 1.27...
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Gas laws.notebook 1 October 14, 2019 Oct 1311:19 AM BOYLE’S LAW Pressure and volume of a gas are inversely proportional to each other, all other factors being constant (such as temperature and amount). Robert Boyle Irish Chemist work done with a Jtube
Transcript of Robert Boyle Irish Chemist work done with a Jtube...Oct 14, 2019 · If we add an additional 1.27...
Gas laws.notebook
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October 14, 2019
Oct 1311:19 AM
BOYLE’S LAW
Pressure and volume of a gas are inversely proportional to each other, all other factors being constant (such as temperature and amount).
Robert Boyle Irish Chemist work done with a Jtube
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October 14, 2019
Oct 131:54 PM
Consider cylinder with piston
gas molecules inside cylinder hit piston and cylinder walls creating pressure
initially pressure inside cylinder is atmospheric pressure, Pa
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October 14, 2019
Oct 131:56 PM
Now apply additional external pressure, Pex. I.e., push down on piston.
note volume is smaller
pressure inside is greater gas molecules hit walls more often
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Oct 131:58 PM
Now pull out piston, to create lower pressure inside.
total pressue (pressure inside) is less than atmospheric pressure
volume of gas is larger
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October 14, 2019
Oct 132:00 PM
Restating Boyle’s Law
as pressure increases, volume decreases
as pressure decreases, volume increases
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Oct 132:01 PM
Example: A gas sample originally has a pressure of 900 . Torr and a volume of 125 mL. If the temperature is constant, what is the pressure of the gas when it occupies 500 . mL?
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October 14, 2019
Oct 132:03 PM
Jacque Charles French physicist
Made 1st solo balloon flight using a H2 filled balloon
His work lead to the relationship between Kelvin and Celsius scales:
K = °C + 273.15
Gas with a volume of zero Temperature would be 0 K.
0 K is called Absolute Zero.
0.000001 K is the lowest temperature reached.
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October 14, 2019
Oct 132:13 PM
CHARLES’ LAW
Volume and temperature are proportional to each other, all other factors being constant.
As temperature decreases, volume decreasesAs temperature increases, volume increases
**Must use temperature on Kelvin scale.**
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October 14, 2019
Oct 132:17 PM
Consider a foil helium balloon
pressure inside is approximately atmospheric pressure
taking balloon from room temperature to cold outside "deflates" balloon
temperature of gas decreases, therefore volume decreases
taking balloon back inside increases temperature, therefore volume increases
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October 14, 2019
Oct 132:25 PM
Example: If the pressure and amount remain the constant, what is the new temperature of a gas initially at 3.6 L and 25 °C, when the volume is changed to 4.8 L?
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October 14, 2019
Oct 133:20 PM
RECALL Avogadro, Italian Chemist
POSTULATED: “Equal volumes of gases at the same temperature and pressure contain the same number of particles”
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October 14, 2019
Oct 133:25 PM
AVOGADRO’S LAW
As the amount (in moles) increases, volume increases.As the amount (in moles) decreases, volume decreases.
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October 14, 2019
Oct 133:27 PM
Consider cylinder with piston and air pump
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October 14, 2019
Oct 133:54 PM
Pumping air into cylinder increases volume.
Pumping air out of cylinder decreases volume.
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October 14, 2019
Oct 134:03 PM
EXAMPLE: A 5.20 L sample at 18.0°C and 2.00 atm pressure contains 0.436 moles of a gas. If we add an additional 1.27 moles of the gas at the same temperature and pressure, what will the total volume occupied by the gas be?
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October 14, 2019
Oct 134:07 PM
IDEAL GAS EQUATIONThree quantities have been found to be proportional to the volume.
Boyle’s Law
Charles’ Law
Avogadro’s Law
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October 14, 2019
Oct 134:13 PM
All three of these proportionalities can be combined into one proportionality.
Including a proportionality constant, the proportionality becomes an equation.
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October 14, 2019
Oct 134:15 PM
Rearranging equation into its most common form yields the Ideal Gas Equation.
P = Pressure in atmV = Volume in Ln = # of molesT = Temperature in KR = Ideal Gas Constant
R = 0.08206 L ꞏ atm/molꞏ K
PV = nRT
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October 14, 2019
Oct 134:27 PM
Note ideal gas equation has 4 variables.
If we know 3 of the variables, we can solve for the fourth variable.
Example: How many moles of gas are in a 2.0 L helium balloon at 25 °C and at atmospheric pressure?
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October 14, 2019
Oct 134:29 PM
Example: What is the volume of one mole of gas at standard temperature and pressure (STP)?
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October 14, 2019
Oct 134:33 PM
Ideal gas equation can be used to find ratios between two sets of conditions. Use ideal gas equation to spot proportionality relationships.
Variables on opposite sides of equation are directly proportional.
Variables on same side of equation are inversely proportional.
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October 14, 2019
Oct 134:34 PM
Example: A constant amount of gas starts at 384 K, 63.2 L and 1.26 atm. What is the new pressure when the volume becomes 43.4 L and the temperature becomes 298 K?
