43 terms

LC Chem 3 Moles, Gases, and Stoichiometry

The amount of a pure substance that contains the same number of particles as there are atoms of carbon-12 in 12g of 12C
6 x 10^23
Avogadro's number (number of particles in 1 mole)
Molar mass
The mass in grams of one mole of the substance.
The spontaneous movement or spreading out of a substance to fill a space due to the natural movement of its particles
A measure of the degree of hotness of an object
Add 273
To convert from Celsius to Kelvin
SI unit of temperature
The temperature at which a gas would occupy no volume, if it could be cooled indefinitely without becoming a liquid or a solid
SI unit of pressure (also called the pascal, Pa)
100000 Pa
Normal atmospheric pressure in Pa
1000 Pa
Number of Pa in 1 kPa = 1,000 Pa.
SI unit of volume
1000 cm3
Number of cm3 in 1 litre
1000000 cm3
Number of cm3 in 1 m3
1000 L
Number of litres in 1 m3
273 K
standard temperature
100000 Pa
standard pressure (Pa)
Boyle's Law
At constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure.
Charles' Law
At constant pressure, the volume of a fixed mass of gas is directly proportional to its temperature measured on the Kelvin scale.
Gay-Lussac's Law of Combining Volumes
In a reaction between gases, the volumes of the reacting gases and the volumes of any gaseous products are in the ratio of small whole numbers provided the volumes are measured at the same temperature and pressure.
P1V1/T1 = P2V2/T2
Equation for Combined Gas Law
Avogadro's Law
Equal volumes of gases contain equal numbers of molecules, under the same conditions of temperature and pressure.
Molar volume
The volume occupied by one mole of any gas
22.4 L
Molar Volume at s.t.p.
24 L
Molar Volume at room temperature and pressure
Assumptions of the Kinetic theory of Gases
1. Gases are made up of particles that are in continuous motion, colliding with each other and with the walls of the container.
2. There are no attractive or repulsive forces between the molecules of a gas.
3. The volume of the gas molecules is negligible compared with the spaces between them.
4. When molecules collide, the collisions are perfectly elastic.
5. The average kinetic energy of the molecules is proportional to the temperature in Kelvin scale.
Limitations to the Kinetic theory of Gases
1. There are attractive and repulsive forces between the molecules of a gas.
2. The volume of the molecules is not negligible compared with the space that they occupy.
3. Collisions are not perfectly elastic.
Ideal gas
One which obeys all the gas laws and under all conditions of temperature and pressure
Low pressure and High temperature
Conditions at which real gases behave most like an ideal gas
Equation of State for an Ideal Gas
Units in which P (pressure) is measured in Ideal Gas Equation
Units in which V (volume) is measured in Ideal Gas Equation
Number of moles of gas present in Ideal Gas Equation
Universal gas constant that converts the units (8.31 J/mol/ K) in Ideal Gas Equation
Units in which T (temperature) is measured in Ideal Gas Equation
Empirical formula
The formula showing the simplest whole number ratio of the numbers of different atoms present in the molecule
Molecular formula
The actual number of atoms of each element present = empirical formula x n
% mass of element
(Atomic mass of element / Molecular mass of compound) x 100
Limiting reactant
The reactant that determines the amount of product formed
In excess
The reactants that are left over are said to be ...
Theoretical yield
The yield of a product that is calculated from the chemical equation.
Actual yield
The yield that is obtained in practice.
Percentage yield
(Actual yield / Theoretical yield) x 100