C3 Quantitative Chemistry

• What is the relative formula mass?

  Sum of all relative atomic masses in a formula
• Why are half equations and ionic equations important?

  They show electron transfer in reactions
• What does the conservation of mass state?

  Total mass of products equals total mass of reactants
• Why is mass conserved in chemical reactions?

  No atoms are lost or made during reactions
• What must be true about chemical symbol equations?

  They must always be balanced
• What happens when solid iron reacts with copper(II) sulfate?

  Produces solid copper and iron(II) sulfate
• What does a half equation represent?

  Changes to one reactant in a reaction
• What do electrons represent in half equations?

  They are written as e⁻
• What do ionic equations simplify?

  They show only species involved in reactions
• What are spectator ions?

  They are ions not involved in the reaction
• What is the ionic equation for the reaction of silver nitrate and sodium chloride?

  Ag⁺(aq) + Cl⁻(aq) → AgCl(s)
• What does the term 'species' refer to in chemistry?

  Different atoms, molecules, or ions in a reaction
• What is the key point about the conservation of mass?

  • Total mass of products equals total mass of reactants
  • No atoms are lost or made
• How is relative formula mass calculated?

  Sum of relative atomic masses in the formula
• What is the relative formula mass of carbon dioxide, CO₂?

  $44$
• Calculate the relative formula mass of calcium nitrate, Ca(NO₃)₂.

  $164$
• Why might some reactions appear to show a change in mass?

  Exchange of matter with surroundings occurs
• What happens when magnesium burns in air?

  Mass of magnesium oxide formed increases
• Why does the mass of products decrease when heating a metal carbonate?

  A gas (carbon dioxide) is lost
• What is the formula for calculating the amount of substance in moles?

  amount (mol) = mass (g) / atomic mass (g/mol)
• How many particles are in one mole of any substance?

  6.02 × 10²³ particles
• What is the mass of one mole of sodium atoms?

  23.0 grams
• How do you calculate the number of moles of carbon dioxide in 33g?

  0.75 mol
• What do balanced equations show?

  Number of moles of each reactant and product
• What is the balanced equation for the reaction of magnesium and oxygen?

  2Mg + O₂ → 2MgO
• What is a limiting reactant?

  It is completely used up in a reaction
• What volume does one mole of any gas occupy at room temperature and pressure?

  24 dm³
• How do you calculate the volume of a gas at room temperature and pressure?

  volume = amount (mol) × 24 dm³
• What are the key points about apparent changes in mass?

  • Some reactions show apparent mass changes
  • Occurs in non-closed systems
  • Gases can enter or leave
• What are the key words in quantitative chemistry?

  • conservation of mass
  • half equation
  • ionic equation
  • species
  • relative formula mass (Mr)
  • relative atomic mass (Ar)
• What are the steps to carry out a titration?

  1. Measure known volume of solution
  2. Add indicator
  3. Slowly add titrant until endpoint
  4. Record volume used
  5. Calculate concentration
• What is said to be in excess in a reaction?

  A reactant that is not used up
• At room temperature and pressure, what volume does one mole of any gas occupy?

  24 dm³
• What is the formula to calculate the volume of a gas at room temperature and pressure?

  volume = amount (mol) × 24 dm³
• What are the steps to calculate the number of moles of sodium in the reaction 2Na + Cl₂ → 2NaCl?

  1. Identify the mass of sodium: 69g
  2. Use the molar mass of sodium (Na = 23 g/mol).
  3. Calculate moles: moles = mass / molar mass.
• How many moles of chlorine are required to react with 69g of sodium?

  1 mole of Cl₂
• What is the mass of chlorine required to react with 69g of sodium?

  71g of Cl₂
• What is the unit for measuring concentration of solutions?

  mol/dm³
• How is the concentration of a solution calculated?

  Concentration = amount of substance / volume
• How many cm³ are in 1.00 dm³?

  1000 cm³