Empirical formula through combustion

• What happens during practical combustion?

  A substance reacts with oxygen when burned
• How can you calculate the empirical formula of a metal oxide using combustion?

  By measuring the mass of the reactants
• What are the steps to calculate the empirical formula of a metal oxide through combustion?

  1. Get a crucible and heat it until red hot.
  2. Leave the crucible to cool, then weigh it.
  3. Add clean magnesium ribbon to the crucible.
  4. Reweigh the crucible with magnesium.
  5. Heat the crucible containing magnesium until combustion occurs.
  6. Weigh the crucible after combustion to find the mass of magnesium oxide.
• What should you do to ensure the crucible is clean before use?

  Heat it until it's red hot
• Why is it important to leave the crucible to cool before weighing?

  To avoid inaccurate mass readings
• What should you do after weighing the crucible with magnesium?

  Heat it until combustion occurs
• What is the significance of weighing the crucible after combustion?

  To determine the mass of magnesium oxide produced
• What is the final product of burning magnesium in air?

  Magnesium oxide
• What happens to the magnesium ribbon during combustion?

  It reacts with oxygen to form magnesium oxide
• How do you find the mass of magnesium oxide produced?

  By subtracting the initial mass from the final mass
• Why is it necessary to allow the crucible to cool before weighing it again?

  To ensure accurate mass measurement
• What should be done to prevent solid bits from escaping during combustion?

  Put the lid on the crucible
• What is the purpose of allowing a small gap in the lid of the crucible?

  To allow oxygen to enter for combustion
• What is the importance of weighing the crucible with its contents after combustion?

  To calculate the mass of magnesium oxide
• How does the mass of magnesium oxide relate to the initial mass of magnesium used?

  The mass of magnesium oxide equals the mass of magnesium plus oxygen
• What is combustion

  When a substance reacts with the oxygen when it’s burned in the air