GAS LAWs Flashcards
Gases definition
Gases are compressible and expand to fill the available volume.
There are 3 variables in the Gas Law equations:
Pressure
Temperature
Volume
When one of these values is _______, the 3 gas laws
constant; predict the relationship between the other two.
Name 4 Laws
Boyle’s Law
Charles Law
Avogadro’s Law
Gay Lussac’s Law
Boyle’s Law (VP)
V1 * P1 = V2* P2
Charles’s Law
V1/ T1 = V2/T2
Avogadro’s Law
V1/n1 = V2/n2
Gay-Lussac’s Law
P1/T1 = P2/T2
Ideal Gas Law
PV = nRT
Combined Gas law
P1 x V1/T1 = P2x V2 / T2
The ideal gas law is most accurate for monatomic gases favored at
high temperatures and low pressures
A value for R is determined under a set of standard conditions called _____
standard temperature and pressure”, or
STP.
Standard temperature is defined as ___C or ____K
0c or 273K.
Standard pressure use to be 1 atm. Using atm/L/mol/K the value is calculated as 0.0821.
However, Standard pressure was changed recently to match SI Units and is now defined as_______
atm/L/mol/K ; 0.0821.
and is now defined as 100 kP
kPa/L/mol/K the value is calculated as
8.31.
The numeric value for R depends on which units are
being used to represent pressure in STP.
If atm, R =
If kPa, R =
- 0821 (old way)
8. 31 (new way)
At STP (_____ kPa, _____K) 1 mole of any gas takes up _____L.
(101.3 kPa, 273K) 1 mole of any gas takes up 22.7 L.
R is expressed in
L/mol/K
Defined Boyle’s Law
The Volume of a gas is inversely proportional to Pressure, if temperature and moles are constant
Boyle’s Law
Increasing pressure, volume ________. This is an ______relationship
We can see that by increasing the pressure on a gas, its volume decreases. This is an inverse, relationship. As one
variable goes up, the other goes down, and vice versa.
Applications of Gas Law
Ambubag being squeezed (increased pressure = decreased volume)
Pushing syringe against resistance (increased pressure = decreased volume)
Inspiration (negative pressure leads to increased volume)
Oxygen cylinder (gas being forced from a larger to smaller container results in
increased pressure in the cylinder
Define Charle’s Law
The Volume of a gas is directly proportional to Temperature (Kelvin), if pressure and moles are constant
For Charle’s Law, By increasing the temperature
he gas expands increasing
the volume. This is a direct relationship.
State Avogadro’s law
There is a ______relationship
As moles of gas increase, the volume increases, and vice versa, if pressure & temperature are constant.
direct
Avogadro’s law example
Using rigid container with movable piston.
Avogadro’s law
(Avogadro’s hypothesis) is one of the gas laws.
Equal volumes of gases, at the same temperature and pressure,
contain the same number of particles, or molecules.
The most important consequence of Avogadro’s law is the following:
The ideal gas constant has the same value for all gases.
One moles of an ideal gas occupies **22.7 liters (dm^3) **at STP (use to be 22.4 L but was changed by IUPAC). This volume is often referred to as the molar volume of an ideal gas. Real gases may deviate from
this value.
A mole is the STP unit of measurement for the amount of a
substance.
STP unit of measurement for the amount of a substance.
Mole =
given weight/molecular weight
The number of molecules in one mole is called Avogadro’s number =
approximately 6.022 ×1023 particles per mole.
Avogadro’s law, together with the ______Formed the ______law
the combined gas law, forms the ideal
gas law.
Gay-Lussac’s Law
As temperature increases, pressure increases, and vice
versa (if volume and moles are constant)
The ideal gas law is the equation of state of an ideal gas.
T
of state of an ideal gas.
The state of an amount of gas is determined by its______, ______ and ______
pressure, volume, and temperature.
Combined gas law.
Used for situations where the value of one or more variables is changing. For example a change in volume and/or pressure and/or temperature and/or the number
of moles.
For the combined gas law Any variables not mentioned can be eliminated from the equation.
be eliminated from the equation.
The gas laws allow us to calculate the behavior of gases
when one of the three factors of pressure, volume, or temperature is maintained unchanged.
Boyle is a
VP
Charles likes
VT
Gay-Lussac is a
PT
Avogadro likes
Vn
Easiest way is to
asiest way is to read the problem and determine if there is a change going on. In other words, is there
a “before” and an “after”. Then fill in all the given
variables and match to the appropriate equation.
May have to convert
Celcius to Kelvin
Charles’ law demonstrates vice versa.
temperature and volume have a direct relationship, which means that the values
always move in the same direction. As the temperature decreases, the volume also decreases and vice versa.
Third Law of Ideal gases
At constant Volume the absolute Pressure of a given mass varies directly with the absolute
Temperature
Vapor pressure
pressure exerted by a vapor
Triple point is
The temperature and pressure at which
it exists simultaneously, in thermodynamic
equilibrium, as a solid, liquid and gas
Room Air at 1 atmosphere = 760mmHg
Air is a mixture of gases; each contributes its partial pressure to the total of 760mmHg. nitrogen constitutes 78.6%, O2 21%, etc. of the atmosphere so multiply the fraction of gas by total to get it’s partial
pressure:
Dalton’s Law of Partial pressure.
PTotal = P1 + P2 + P3 …
All matter exists in one of three states or phases
Solid, liquid, or gas
When a gas co-exists in equilibrium with its corresponding liquid, the gas is termed a vapor
termed a vapor
In chemistry and physics, Dalton’s law (also called Dalton’s law of partial pressures) states that the tses do not react with each other.
the total pressure exerted by a gaseous mixture is equal to the sum of the partial pressures of each individual component
in a gas mixture. It is assumed that the gases do not react with each other.
The combined gas law combines
Charles’s law, Boyle’s law, and Gay-Lussac’s law.
The combined gas law combines (CBG)
Charles’s law, Boyle’s law, and Gay-Lussac’s law.
Combined law
The law states that the product of the volume of a gas and its pressure over the temperature is equal to a constant
Gay-Lussac’s law shows a direct relationship between pressure and temperature,
that if temperature increases, so does the pressure
the gas exerts.
To find total pressure
add all partial pressures together.
According to Gay-Lussac’s law, if
the pressure decreases, the temperature
should decrease.
According to Gay-Lussac’s law, if
the pressure decreases, the temperature
If pressure increases, temperature______
should decrease.
increases
Hormonal control of BP steps:
Renin –> Angiotensinogen –>Angiotensin I –> ACE –> Angiotensin II–> Vasoconstriction = increased BP
–>Aldosterone : stims. Kidney to reabsorb Na+, water follows salt = increased BP
At STP, Pressure is
Temperature is
Volume of 1 mole
100KPa
273K
22.7 L
Ideal Gas law applied exactly to only ideal gas which______however, when does real gases approach ideal gases behavior?
does not exist
As pressure decrease, TEMPERATURE INCREASES
Boyle’s law states
the volume of a fixed quantity of gas is INVERSELY PROPORTIONAL to the pressure
When should you use the Ideal gas law?
when the problem described only a single state (Temp, pressure and/or volume)
The EMPIRICAL gas laws are useful for changing the state of a gas (P,n, V and or T change)
What is R and has unit of
Universal gas constant; energy/mol/K –>8.31 J/mol/K
What is STP?
Standard temperature and pressure
What is the standard molar volume of an ideal gas?
Is the volume occupied by 1 mole of gas at STP. the SMV is 22.7L.
How do you find the SMV?
Start with ideal gas law –> PV=nRT
When calculating volume for ideal gas law
V = nRT/P
What will happen to the volume of a gas if both the pressure and temperature are increased?
Increasing the pressure will decrease the volume, increasing the temperature will increase the volume. The change in volume depend on the relative sizes of the changes in temperature and pressure
Dalton’s law
Total pressure in a mixture of gases is equal to the pressure that each component exert in the absence of all others. Called the partial pressure.
The greater atomic mass of two gas will
Travel in more time , the gas with the less atomic mass will take less time.
BREATHING IS BASED ON THIS LAW
Boyle’s law
When concerned about the non-ideal behavior of gases, it is best to use this law
Van der Waals equation
Uranium is enriched by allowing mixtures of U and u to race down a long tube
Graham’s Law
The composition of a gaseous mixture is measure by the pressure of each gas?
Dalton’s Law
You know your tires are good, but they look flatter in the winter, Assume the pressure has not changed,
Charle’s Law
This gas law is best to using with dealing with gas in a single state
Ideal Gas law
