C3 - Quantitative Chemistry

• What is the purpose of quantitative analysis in chemistry?

  To determine formulae and reaction equations
• How do analysts use quantitative methods in chemistry?

  To determine purity and monitor yield
• What are the classifications of chemical reactions used for?

  • To understand how chemicals react
  • To establish patterns in reactions
  • To predict behavior of other chemicals
• What do chemical equations represent?

  They represent chemical reactions
• Why are chemical equations important for chemists?

  They communicate chemical ideas effectively
• How does identifying different types of chemical reactions benefit chemists?

  It helps in understanding chemical interactions and predictions
• What does the law of conservation of mass state?

  No atoms are lost or made in reactions
• How can chemical reactions be represented?

  By balanced symbol equations
• What do multipliers in equations represent?

  Numbers of atoms of each element
• What is the relative formula mass (Mr) of a compound?

  Sum of relative atomic masses in the formula
• What does a balanced chemical equation indicate about masses?

  Mass of reactants equals mass of products
• How do you calculate percentage by mass in a compound?

  Using relative formula mass and atomic masses
• Why might a reaction appear to involve a change in mass?

  Because a gas's mass is not accounted for
• What happens when a metal reacts with oxygen?

  The mass of the oxide is greater than the metal
• What is the particle model used for in mass changes?

  To explain changes in non-enclosed systems
• What is always present in measurements?

  Some uncertainty about the result
• How can uncertainty in measurements be represented?

  By the distribution of results
• What is the unit for measuring chemical amounts?

  Moles, symbol mol
• How is the mass of one mole of a substance related to its relative formula mass?

  They are numerically equal in grams
• What does one mole of a substance contain?

  The same number of particles as any mole
• What is the value of the Avogadro constant?

  $6.02 \times 10^{23}$ per mole
• How does the measurement of amounts in moles apply to carbon?

  One mole of carbon equals one mole of CO2 molecules
• How can masses of reactants and products be calculated?

  From balanced symbol equations
• What does the equation Mg + 2HCl represent?

  One mole of magnesium reacts with two moles of HCl
• How can you calculate the masses of substances in a balanced equation?

  By using the balanced symbol equation
• How can balancing numbers in a symbol equation be calculated?

  By converting masses to moles and ratios
• What is a limiting reactant?

  The reactant that is completely used up
• How does a limiting reactant affect product amounts?

  It limits the amount of products formed
• How is concentration of a solution measured?

  In mass per volume, e.g., g/dm³
• How can you calculate the mass of solute in a solution?

  From its concentration and volume
• What is the percentage yield of a product?

  Actual yield compared to theoretical yield
• How do you calculate percentage yield?

  % Yield = (Actual mass / Theoretical mass) × 100
• What factors can affect the yield of a product?

  Reversibility, product loss, unexpected reactions
• What is atom economy?

  Measure of starting materials as useful products
• How is percentage atom economy calculated?

  Relative mass of desired product / Sum of reactants' masses × 100
• Why is high atom economy important?

  For sustainable development and economic reasons
• How can concentration in mol/dm³ be related to mass and volume?

  It relates to the amount of solute in solution
• How can you calculate the concentration of a solution?

  From moles of solute and volume of solution
• What can be determined through titrations?

  Concentrations of strong acids and alkalis
• What do equal amounts in moles of gases occupy under the same conditions?

  The same volume