Determining an equation experimentally: magnesium oxide
I can describe a safe experiment to calculate the reacting molar ratios for the oxidation of magnesium.
Determining an equation experimentally: magnesium oxide
I can describe a safe experiment to calculate the reacting molar ratios for the oxidation of magnesium.
Lesson details
Key learning points
- Heating magnesium in a crucible will react it with oxygen.
- The crucible must be opened periodically to ensure enough oxygen enters the vessel to completely oxidise the magnesium.
- Opening the crucible too much will cause mass/product loss.
- Safety precautions should be taken when burning magnesium because of the bright light produced.
- The stoichiometry for a reaction can be calculated given experimental data.
Common misconception
Pupils sometimes struggle to understand that 'heating to constant mass' takes time and multiple measurements.
Link the idea that atoms rearrange during a reaction and that for all atoms of a substance to be oxidised, enough oxygen must be present. If the product measurements show a 'constant mass' we can be confident that complete oxidation has occurred.
Keywords
Limiting reactant - the reactant that completely reacts, thereby determining the maximum amount of product that can be formed in a chemical reaction. All other reactants will be present in excess
Ratio - used to determine the size of one quantity in relation to another
Stoichiometry - the molar ratio of the reactants and products in a chemical reaction
Mole - A mole of a substance is 6.02 × 10²³ particles of it. The mass of a mole of a substance is its relative mass in grams.
Balanced symbol equation - describes a reaction using a symbol equation with coefficients which ensure there are equal numbers of atoms of each element on both sides of the equation
Equipment
Mg strip, crucible + lid, clay triangle, tripod, Bunsen burner, heatproof mat, tongs, balance.
Content guidance
- Risk assessment required - equipment
Supervision
Adult supervision required
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Video
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Starter quiz
6 Questions
Reaction in which oxygen atoms bond to the elements of the reactants.
The reactant that completely reacts during a reaction.
A reactant that remains at the end of a reaction.
How many moles of each chemical we need to react to make the products.
Exit quiz
6 Questions
The molar ratio of the reactants and products in a chemical reaction.
The unit of substance.
Substance that completely reacts during a reaction.
The mass remains the same.