calculations

• What is the formula mass?

  The formula mass is the sum of the atomic masses of all atoms in a compound’s formula.
• How do you calculate the formula mass of H₂O?

  Add the atomic masses: \( 2 \times 1 + 16 = 18 \).
• What is Avogadro's constant?

  Avogadro's constant is \( 6.02 \times 10^{23} \).
• What does Avogadro's constant represent?

  It represents the number of particles in one mole of any substance.
• How do you convert moles to the number of particles?

  Use the formula: Number of particles = Moles × Avogadro's constant.
• What is theoretical yield?

  The theoretical yield is the amount of product expected if a reaction goes perfectly.
• What is percentage yield?

  Percentage yield is the ratio of actual yield to theoretical yield, expressed as a percentage.
• What is the formula for calculating percentage yield?

  \( \text{Percentage Yield} = \left( \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \right) \times 100 \)
• Why is percentage yield important?

  It indicates the efficiency of a reaction and accounts for losses and side reactions.
• What does atom economy measure?

  Atom economy measures how efficiently a reaction uses its atoms.
• What is the formula for calculating atom economy?

  \( \text{Atom Economy} = \left( \frac{\text{Molar Mass of Desired Product}}{\text{Total Molar Mass of Reactants}} \right) \times 100 \)
• Why is high atom economy desirable?

  High atom economy reduces waste and is important in green chemistry.
• What is concentration in chemistry?

  Concentration is the amount of solute dissolved in a given volume of solution.
• What is the formula for concentration in grams per dm³?

  \( \text{Concentration} = \frac{\text{Mass of Solute (g)}}{\text{Volume of Solution (dm³)}} \)
• What is the formula for concentration in mol per dm³?

  \( \text{Concentration} = \frac{\text{Moles of Solute}}{\text{Volume of Solution (dm³)}} \)
• What is Avogadro’s Law?

  At room temperature and pressure, one mole of any gas occupies 24 dm³.
• How do you calculate the volume of gas at RTP?

  Use the formula: Volume of gas at RTP (dm³) = Moles of gas × 24.
• What is titration in chemistry?

  Titration is a method to determine the unknown concentration of a solution.
• What are the steps for performing a titration?

  1. Measure a volume of acid or alkali and place it in a flask with an indicator.
  2. Add the other reactant from a burette until the indicator changes color, marking the end point.
• What is the key calculation involved in titration?

  Use the formula \( \text{Concentration (mol/dm³)} = \frac{\text{Moles}}{\text{Volume (dm³)}} \).
• What is a limiting reactant?

  The limiting reactant is the reactant that is completely used up in a reaction.
• How do you identify the limiting reactant?

  Write the balanced equation and calculate the moles of each reactant.
• What is the process to determine which reactant is limiting?

  Use ratios to see which reactant is limiting and which is in excess.
• What are the key terms to memorize for this chapter?

  • Atom economy: Efficiency of atom use in reactions.
  • Avogadro’s constant: \( 6.02 \times 10^{23} \) particles/mole.
  • Percentage yield: Comparison of actual to theoretical yield.
  • Concentration: Amount of solute per unit volume.
  • Limiting reactant: Reactant that limits the amount of product.
• What are some practice tips for preparing for the chemistry test?

  • Work through problems calculating formula masses, yields, atom economy, and concentrations.
  • Memorize key formulas.
  • Use units carefully and convert where necessary.
  • Understand ratios for limiting reactant questions and balancing equations.