GCSE Chemistry (AQA)

196 videos | 19 hours

Reacting Mass Calculations

Please subscribe to watch this video.

This, and all other videos, are included in our premium subscriptions.

Premium accounts get access to all videos.

Quantitative chemistry Use of amount of substance in relation to masses of pure substances

Reacting Mass Calculations

11:05 Moles, Mass, and Balanced Equations
Spec 4.3.2.2 4.3.3.1
Previous Mole Calculations Next Limiting Reactants
  • Reacting mass calculations determine the amount of product formed from a given amount of reactant.
  • Important for lab reactions and large-scale industrial reactions.
  • Balanced symbol equations are used to find the ratio between reactants and products.
  • Multipliers in chemical equations show the number of each compound involved.
  • Example: 1 magnesium atom reacts with 2 HCL molecules to form 1 magnesium chloride molecule and 1 hydrogen molecule.
  • The ratio allows calculation of moles of product from moles of reactant.
  • Example calculation: Determine mass of ammonia from 10.0 grams of hydrogen using balanced equation N2 + 3H2 ��� 2NH3.
  • Steps for calculation:
  • 1. Calculate moles of reactant using N = M/MR.
  • 2. Find ratio of reactant to product from balanced equation.
  • 3. Calculate moles of product from moles of reactant.
  • 4. Calculate total moles of product formed.
  • 5. Calculate mass of product formed.
  • Example: Calculate mass of oxygen needed to react with 0.005 kg of calcium to form calcium oxide using equation 2Ca + O2 ��� 2CaO.
  • Steps for calculation:
  • 1. Calculate moles of given reactant.
  • 2. Find ratio between reactants from balanced equation.
  • 3. Calculate moles of second reactant needed.
  • 4. Calculate total moles of second reactant required.
  • 5. Calculate mass of second reactant required.
  • Example result: 2.00 grams of oxygen needed for the reaction.

Please subscribe to access these revision notes.

This, and all other video notes, are included in our premium subscriptions.

Premium accounts get access to all videos and revision notes.