A-level Chemistry/AQA/Module 1/Amount of Substance

Relative Atomic Mass and Relative Molecular Mass

The isotope ¹²C is the standard for relative mass.

The Avogadro Constant is a quantity and is given the symbol L:

   L = 6.023 x 10²³ particles mol^-1

The mole is a quantity of particles:

   1 mole is 6.023 x 10²³ particles

1 mole of ¹²C has a mass of precisely 12.000g because ¹²C is the standard.

is a quantitative expression of the concentration of a solution

Isotopes have different mass numbers but the same atomic numbers OR they have the same number of protons but different numbers of neutrons

$p V = n R T$

p is the pressure of the gas in Pa (Nm^-2)

V is the volume of the gas in m³

n is the number of moles

R is the gas constant (8.31 J K^-1 mol^-1)

T is the temperature in kelvin