Boyles law
- Boyle’s law states that the pressure of an ideal gas increases as its container volume decreases.
- The volume of an ideal gas is inversely proportional to its absolute pressure at a constant temperature.
Equation
PV = K
Where
P = pressure
V = Volume
K Is the constant
To find pressure or volume, the equation becomes
Pi Vi = Pf Vf
Pi = initial pressure of the gas
Vi = initial volume of the gas
Pf = Final pressure
Vf = Final volume
Example. 1
A tank of volume 250 L, is evacuated and connected to a 50 L bulb filled with air. When the two are joined, the air pressure inside the bulb drops to 2.20 atm, while the temperature remains the same. Find the initial pressure In the 50L bulb
Solution
In this sample question, we are provided with the initial volume of the bulb, final volume, and final pressure.
Pi Vi = Pf Vf
P initial = ?
V initial = 50 L
P final = 2.20 atm
V final = (50L +250L) = 300 L
We can make P initial the subject of the formula as follows
Pi * 50 = (2.2 * 300)
Pi = (2.2 *300) / 50
Pi = 13.2 atm
The initial pressure of the 50 L bulb is 13.2 atm
Revision
P1V1=P2V2
What is the formula for Boyle’s Law?
Kelvin (K)
Celcius
Ferenheit
Give three units of Temperature
given
unknown
equation
setup
solve
What does GUESS mean?
T
What is the symbol for temperature?
gay-lussac’s law
P1T2=P2T1
volume
what’s constant in Gay-Lussac’s law?
write down and label all the givens
After reading a gas law problem, what should the first step be in solving?
Direct proportions; one goes up the other goes up. Inverse; one goes up the other goes down.
What is the difference between inverse and direct proportions?
T1V2=T2V1
What is the formula for Charles’ Law?
Boyle’s Law
P1V1=P2V2
Pressure
What is constant in Charles’ Law?
Van der Waal’s equation
What is another name for the real gas law?
Combined gas law
P1V1T2=P2V2T1
A=molecular attraction
B=molecular volume
What two factors of a real gas are not considered in an ideal gas?
P
What is the symbol for pressure?
Diffusion
A ballon deflates over time. What is this an example of?
atm (atmosphere)
torr
kPa (kilopascals)
mmHg (milimeters of mercury)
Give three units of pressure
Temperature
What is constant in Boyle’s law?
P1T2=P2T1
What is the formula for Gay-Lussac’s Law?
ideal gas law
PV=nRT
V
What is the symbol for volume?
Standard temperature and pressure;
273 K, 101.3 kPa, 1.0 atm, 760 mmHg/torr
What is STP?
Dalton’s law (Dalton’s partial pressure law)
Pt=P1+P2+P3…..
mL, L, dm3, cm3
(dm3=L) (cm3=mL)
Give three units of volume
Charles’ Law
T1V2=T2V1
PV=nRT
What is the formula for the combined gas law?
n
What is the symbol for the number of moles?
PV=nRT
What is the formula for ideal gas law?
if the units for pressure or volume changed
Why would the ideal gas law (R) constant change?
Pt=P1+P2+P3…..
What is the formula for Dalton’s Law?
The spreading of molecules from a high concentration to a low concentration. Spraying air freshener or perfume and smelling it from another room or farts.
What is diffusion? Give an example.
22.4 L
How many liters are in a mole of STP?
The combined gas law is called such because it combines Boyles’, Gay-Lussac’s, and Charles’ law.
Why is the combined gas law called such?
amount
What is held constant in a combined gas law?
Temperature; Amount; Pressure; Volume; inversly
Boyle’s law – When _ and are held constant, _ and are _ proportional.
Amount; Pressure; Temperature; volume; directly
Charles’ Law – When _ and are held constant, and _ are directly proportional.
used when givens are estimated for gas
When is STP used?
Pressure
amount
temperature
volume
factors that could affect a gas
used to that all gasses are treated the same way. IT negates molecular attraction and molecular volume
When are Ideal Gases used?
…
ANY LAW WITH TEMPERATURE IN THE EQUATION MUST BE CHANGED INTO KELVIN
homogenous mixture of substances.
What is a solution?
Total pressure exerted by a gas is equal to the sum of the partial pressures of each gas in the solution
What is dalton’s law?
gas formed by the water particles in the air. It is used to determine the opressure of a “dry” gas, using daltons law
What is water vapor and when is it formed?
P+(an^2)/(v^2) = nRT
What is Van der Waal’s equation?
Kelvin and Liters
What should the Volume and Temperature always be in when working with the ideal gas formula?
