Gas laws Flashcards
There are three gas laws
- Boyle’s Law;
- Charles’ Law; and •
- The Law of Pressures
they combine into general gas laws
what provides the basis of the gas laws, the rules by which the behaviour of gases can be determined
As we have seen, each solid or liquid will expand with rise in temperature by an extent determined by the coefficient of cubical expansion. However, all gases expand by the same amount for the same temperature rise Changes in volume of a gas depend on changes in temperature and pressure. To study the interaction between temperature, pressure and volume, one of these quantities is kept constant and the dependence of the other two on each other can then be studied.
Boyles law and explain give a brigade example
for a gas at constant temp the volume of a gas is inversely proportional to the pressure upon it Experiments show that if the pressure applied to a given volume of gas is doubled, the volume is halved. If the pressure is trebled, the volume is reduced to one-third, provided the temperature is constant This is why the pressure gauge on a breathing apparatus set is a measure of how much air there is in the cylinder P1 X V1 = P2 X V2
Charles law and explain formula
for a gas at a constant pressure,the volume increases by 1/273 rd at 0 degrees centigrade for every degree increase V1/T1 =V2/T2
law of pressures or Gay Lusaacs law formula example
for a gas at constant volume the pressure is directly proportional to the absolute temperature P1/T1 =P2/T2 This is the case when a cylinder of gas, whose valve is closed, is heated, as could happen if it were in a fire
The General Gas Law
The three gas laws can be combined into a single mathematical expression P1 X V1 P2 X V2 ———— = —————- T1 T2 Remembering this law will allow you to remember all three - you can just remove the quantity which is being kept constant from both sides of the equation.
equation for Boyles law
When the volume decreases the pressure increases. This shows that the pressure of a gas is inversely proportional to its volume.
From this we can derive the equation:
p_
p1 V1 = p2 V2
Where:
p_1is the starting pressure
V_1is the starting volume
p_2is the finishing pressure
V_2is the finishing volume
Charles equation
V1/T1 = V 2
Kelvin (or Absolute) scale of temperature must be used, and that the relationshipbetween volume and temperature is/T2
combined gas laws equation
The Combined Gas Law
Imagine a world in which you didn’t need to memorize the three laws above. Instead, there was one big law that covered both of them. Hey, that’s the world you live in now, and the law you need to know is the combined gas law:
P1 V1 / T 1 = P2 V2 / T2
In this equation, all of the terms are exactly the same as in the preceding equations. The way you can use this equation is that whenever you’re changing the conditions of pressure, volume, and/or temperature for a gas, you just plug the numbers into this equation
what is the law of pressures or Gay Lusaccs Law
P1/T1 = P2/T2
This gas law explains how if you increase the temperature of a container with fixed volume, the pressure inside the container will increase. This explains why you shouldn’t leave cans of spray paint in your trunk - the pressure might get so high that the propellant will blow the can up.
What is sublimation
In the laboratory it is possible to produce such low
pressures that the boiling point of water can be
reduced to 0°C and lower. When this happens, ice
does not melt to form water, but will vaporise completely
as the temperature rises.
This direct change from solid to vapour without
forming an intermediate liquid is given the special
name of sublimation.
In order to achieve sublimation with water,
extremely low pressures are required, but solid
carbon dioxide sublimes at atmospheric pressure.
Explain The liquefaction of gases and give examples
Many substances which are gases at normal temperatures
and atmospheric pressure can be compressed
to such an extent that their boiling point is
raised above atmospheric temperature and the gas
liquefies (e.g., propane, ammonia).
Other gases cannot be liquefied at atmospheric
temperature no matter how great a pressure is
applied.These are the so-called “permanent gases’.
However, if the temperature is lowered sufficiently,
it becomes possible to liquefy them by compression
(e.g., methane, oxygen).
NOTE FOR CYLINDERS OF LIQUIFIED GAS THE PRESSURE IS NOT AN INDICATION OF AMMOUNT OF GAS IN A CYLINDER. WHERAS A TRUE GAS WILL OBEY THE GAS LAWS.
