What is the empirical formula?
The simplest whole-number ratio of atoms of each element present in a compound.
How do we calculate the empirical formula?
Mass given/Aᵣ to find ratio.
Check camera roll.
What is the molecular formula?
Shows the actual numbers of the atoms of each element in the compound.
How do we calculate the molecular formula from the empirical formula?
Divide the molecular mass by the empirical formula mass to find the multiplier.
What is the required apparatus to find the empirical formula by experiment (magnesium oxide)?
- Heat-resistant mat
- Tripod
- Pipeclay triangle
- Magnesium
- Crucible
How do we find the empirical formula by experiment (magnesium oxide)?
- Find the mass of crucible + lid
- Find the mass of crucible + lid + magnesium
- Heat crucible + lid + magnesium
- Lift the lid occasionally to allow oxygen in
- Heat until there is no further change in mass
- Allow crucible to cool
- Find mass of crucible + lid + magnesium oxide
- Find mass of magnesium element and oxygen element separately
What is the law of conservation of mass?
When a solute is dissolved in a solvent to make a solution, the overall mass of the substances does not change.
What is a closed system?
A system where substances cannot enter or leave.
What is a non-enclosed system?
A system where substances can enter or leave.
How do we calculate the concentration of a solution?
mass of solute (g)
Concentration = __________________________
volume of solution (dm³)
What is the Avogadro constant?
6.02 x 10²³
How do we calculate the moles of any substance?
mass of substance (g)
Moles = _______________________
Aᵣ or Mᵣ
What is a limiting reactant?
The reactant that determines the amount of product formed in a chemical reaction. Any other reactants will be present in excess.
