CHAPTER SIX- GASES Flashcards
The most important gas in the atmosphere (to us) is _______, which constitutes about ______% of the atmosphere.
Oxygen; 21%
Of the elements on the periodic table, only a handful of exist as gases at room temperature. What are they?
H2, N2, O2, F2, Cl2 and the noble gases.
Another group of gases includes the oxides of the nonmetals on the upper right coercer of the periodic table, such as _________
CO, CO2, NO, NO2, SO2 and SO3.
Generally molecules that are gases at room temperature have fewer than ____ atoms from the first or second period.
5
What are the characteristics of gases?
- Gas particles are (close or far apart?).
- A gas has no definite ______ or ______ and will _________ fill any container.
- The attractive forces between gas particles are _________
Gas particles are far apart.
A gas has no definite shape or volume and will completely fill any container.
The attractive forces between gas particles are minimal
What is the KINETIC MOLECULAR THEORY OF GASES?
It is a model for the behavior of a gas; helps us understand gas behavior.
The KINETIC MOLECULAR THEORY OF GASES:
- A gas consists of small particles (______ or ________) that move ________ with ______ velocities.
This causes a gas to fill the _______ ______ of a container.
atoms or molecules that move randomly with high velocities.
entire volume
The KINETIC MOLECULAR THEORY OF GASES:
- The attractive forces between the particles of a gas are usually very _________.
Gas particles are _______ ______ and fill a container of _________ size or shape.
small
far apart; fill a container of any size or shape
The KINETIC MOLECULAR THEORY OF GASES:
- The actual volume occupied by gas molecules is considered _______ ________ compared with the volume that the gas occupies.
The volume of the gas is considered ______ the volume of the container.
Most of the volume of a gas is _____ ______, which allows gases to be easily ________.
extremely small
equal to
empty space, compressed
The KINETIC MOLECULAR THEORY OF GASES:
- Gas particles are in constant motion, moving _______ in ________ paths.
When gas particles collide, they ______ and travel in _______ __________. Every time they hit the walls of the container, they ____ ____.
An increase in the number of collisions against the walls of the container causes an increase in the ___________.
rapidly, straight
rebound, new directions, exert pressure
pressure of the gas
The KINETIC MOLECULAR THEORY OF GASES:
The average kinetic energy of gas molecules is proportional to the _____ temperature.
Gas particles move ______ as the temperature increases. At higher temperatures, gas particles hit the walls of the container _______ often, with _______ force, producing _______ pressures.
Kelvin
faster
more, more, higher
When we talk about a gas, we describe it in terms of 4 properties, which are….
pressure, volume, temperature and the amount of gas
See the chart on page 217 for a summary of the four properties of a gas (Table 6.1)
What is atmospheric pressure?
The gas particles in the air, mostly oxygen and nitrogen, exert a pressure on us called ATMOSPHERIC PRESSURE.
As you go to higher altitudes, the atmospheric pressure is less because there are fewer particles in the air.
PRESSURE (P):
The most common units used for gas pressure measurement in the US are _______ and ________.
…or __________ in other countries.
- the atmosphere (atm)
- millimeters of mercury (mmHg)
… kilopascals
VOLUME (V):
The volume of gas equals ___________
When you inflate a tire or a basketball, you are ____________. The _______ in the number of particles hitting the walls of the object _______ its volume.
The most common units for volume measurements are _____ and ______
the size of the container in which the gas is placed.
…adding more gas particles; increase, increases
liters (L) and milliliters (mL)
TEMPERATURE (T):
The temperature of a gas is related to the _____ ______ of its particles.
Although you measure gas temperature using a ________ thermometer, all comparisons of gas behavior and all calculations related to temperature must use the ______ temperature scale.
kinetic energy
Ex: if we have a gas at 200 K in a rigid container and heat it to a temperature of
400 K, the gas particles will have twice the kinetic energy that they did at 200 K.This also means that the gas at 400 K exerts twice the pressure of the gas at 200 K.
Celsius; Kelvin
AMOUNT OF GAS (n):
Usually we measure the amount of gas by its mass in ___________. In gas law calculations, we need to change the ____ of gas to ________.
grams
grams; moles
When billions and billions of gas particles hit against the walls of a container, they exert __________, which is defined as _______________ (also give the formula)
pressure
a force acting on a certain area
Pressure (P)= force/area
The atmospheric pressure can be measured using a ____________.
One ATMOSPHERE (atm) is defined as EXACTLY __________ mmHg
One atmosphere is also ______ torr, a pressure until named to honor the inventor of the barometer.
barometer
760 millimeters of mercury
760 torr. Because they are equal, until of torr and mmHg are used interchangeably.
1 atm= 760 mmHg = 760 torr (exact)
1 mmHg = 1 torr (exact)
In SI units, pressure is measured in _______.
1 atm is equal to ____________ of these.
pascals (Pa)
1 atm= 101.325 Pa
Because pascal is a very small unit, it is likely that pressures would be reported in kilopascals.
1 atm= 1.01325 x 10^5 Pa = 101.325 kPa
The US equivalent of 1 atm is ___________.
14.7 lb/in.^2 (psi)
1 atm= 14.7 lb/in.^2
Atmospheric pressure changes with variations in ________ and ________.
weather and altitude
hot day- a column of air has more molecules, which increase the pressure on the mercury surface. The mercury column rises, indicating a higher atmospheric pressure.
rainy day- atmosphere exerts less pressure, which causes the mercury column to fall. (Low pressure system)
above sea level- the density of the gases in the air decreases, which causes lower atmospheric pressures.
below sea level- at the Dead Sea, the atmospheric pressure is greater than 760 mmHg. Divers must be concerned about increasing pressures on their ears and lungs.
BOYLE’S LAW- Pressure and Volume
When a change in one property causes a change in another property, the properties are related. If the changes occur in opposite directions, the properties have an INVERSE RELATIONSHIP.
The inverse relationship between PRESSURE and VOLUME of a gas is known as BOYLE’S LAW.
The law states that the volume (V) of a sample of gas changes inversely with the pressure (P) of the gas as long as there is no change in the temperature (T) or amount of gas (n).
P1V1= P2V2
In BOYLE’S LAW, if the volume or pressure of a gas sample changes without any change in the temperature or in the amount of the gas, the new pressure and volume will give ______.
…the same PV product as the initial pressure and volume. Then we can set the initial and final PV products equal to each other.
