C4 Stoichiometry

Formula of simple compound

Obtained by swapping valency numbers

Can be cancelled if possible

Example: Potassium oxide

K - Valency of 1. O - Valency of 2

Swap them over the equation will be K2O

Example: Magnesium oxide

Mg - Valency of 2. O - Valency of 2

Swap them over, in this case itll be cancelled out due to similar valency

Writing equations

Definitions

Relative atomic mass (Ar)

average mass of naturally occurring atoms of an element, on scale where the 12C atom has a mass of exactly 12 units

Relative formula mass (Mr)

sum of the relative atomic masses

Example Mg Ar = 24. Oxygen Ar = 16. The Mr of MgO = 40g

Mole

Amount of substance that contains 6x10^23 atoms, ions or molecules

One mole of a substance has a mass equal to the Mr

Mole quations

No. moles = Mass of substance/mass of one mole

Number of moles of gas = Volume of gas (dm^3) at rtp / 24

Moles (solute) = concentration (moldm^-3) x volume (dm^3)

Concept of mole ratio

Mole ratio is the ratio between the amounts in moles of any two compounds involved in a chem reacion