Avogadroâs number (N) is the number of atoms in 12.01 grams of carbon. In chemistry, this is equivalent to a mole.Â
Its numerical value is 6.02 x 10²³ particles.
The atomic mass of each element on the periodic table contain 6.02 x 10²³ atoms.
The volume occupied by one mole of softballs would be about the size of Earth.Â
One mole of Olympic shot put balls has about the same mass as that of Earth.Â
One mole of hydrogen atoms laid side by side would circle Earth about 1 million times.
Remember the mole (mol) is a unit of measure for an amount of a chemical substance. A mole is also Avogadroâs number of particles, which is 6.02 x 10²³ particles.
1 mol = 6.02 x 10²³ units
We can use the mole relationship to convert between the number of particles and the moles of a substance.
Molar mass is the mass of 1 mole of a substance in grams.Â
For example, the atomic mass of carbon is 12.01 amu, so:
the molar mass (mass per mole) of carbon is 12.01 g/mol.
Since nitrogen occurs naturally as a diatomic, N2:Â
the molar mass of nitrogen gas is 2 x 14.01 or 28.02 g/mol.
The molar mass of a substance is the sum of the molar masses of each element.
Hydrogen - 2 x 1.01 g/mol = 2.02 g/mol
The molar mass of Cu(NO2)2
Nitrogen - Â 2 x 14.01 g/mol = 28.02 g/mol
Oxygen - 4 x 16.00 g/mol = 64.00 g/mol
Using the triangles below, we can find:
moles x 6.02 x 10²³ = number of particles.
number of particles á 6.02 x 10²³ = moles.
moles x molar mass = mass.
mass á moles = molar mass.
mass á molar mass = moles.
Some calculations are two step problems. This is indicated by the absence of the word âmoleâ in the question.
At Standard Temperature and Pressure or STP (which is 0° Celsius and 1 atmosphere) 1 mol of any gas occupies 22.4 L. The volume occupied by 1 mol of gas (22.4 L) is called the molar volume.
moles x 22.4 L/mol = volume
volume á 22.4 L/mol = moles
The density of gases is much less than that of liquids. The density of any gas at STP can be easily calculated, with this formula:
There are three interpretations for the mole:
1 mol = 6.02 x 10²³ particles
This gives us three ways to convert between moles, particles, mass and volume.
The percent composition of a compound lists the mass percent of each element.
For example, the percent composition of water (H2O) is 11% hydrogen and 89% oxygen. Regardless of the size of the sample, the composition (and therefore, percent) is the same.