Conservation Of Mass

• What is the principle of conservation of mass?

  Mass cannot be created or destroyed.
• Why is the conservation of mass useful in chemical reactions?

  It helps calculate amounts of substances.
• What happens to atoms during a chemical reaction?

  No atoms are destroyed or created.
• What does it mean when we say mass is conserved during a reaction?

  Mass remains the same before and after.
• In the reaction 2Li + F₂ → 2LiF, how many lithium atoms are present on each side?

  2 lithium atoms
• How can you verify that mass is conserved in a balanced equation?

  By adding relative formula masses on both sides.
• What is the total relative formula mass of the reactants in the equation 2Li + F₂?

  $52$
• What is the total relative formula mass of the products in the equation 2Li + F₂?

  $52$
• What happens to mass if a gas is a reactant in an unsealed reaction vessel?

  The mass increases as gas is contained.
• Why might the mass decrease in an unsealed reaction vessel?

  A gas product escapes from the vessel.
• What are the two explanations for mass change in an unsealed reaction vessel?

  1. Mass increases if a gas reacts and is contained.
  2. Mass decreases if a gas escapes during reaction.
• What is the total mass of reactants compared to products in a chemical reaction?

  They are always equal.
• In the reaction H₂SO₄(aq) + 2NaOH(aq) → Na₂SO₄(aq) + 2H₂O(l), what is the atomic mass of hydrogen?

  $1$
• What is the atomic mass of oxygen in the reaction H₂SO₄(aq) + 2NaOH(aq) → Na₂SO₄(aq) + 2H₂O(l)?

  $16$
• What is the atomic mass of sodium in the reaction H₂SO₄(aq) + 2NaOH(aq) → Na₂SO₄(aq) + 2H₂O(l)?

  $23$
• What is the atomic mass of sulfur in the reaction H₂SO₄(aq) + 2NaOH(aq) → Na₂SO₄(aq) + 2H₂O(l)?

  $32$
• What is the process to show mass conservation in a chemical reaction?

  1. Identify reactants and products.
  2. Calculate total mass of reactants.
  3. Calculate total mass of products.
  4. Compare both totals to confirm equality.