chemistry quantitive chemistry

• What does the law of conservation of mass state?

  No atoms are lost or made in reactions
• How does the law of conservation of mass apply to chemical reactions?

  The mass of products equals the mass of reactants
• What is the balanced equation for magnesium reacting with hydrochloric acid?

  Mg + 2 HCl → MgCl2 + H2
• What is relative atomic mass (RAM)?

  Average mass of atoms in an element
• How is relative formula mass (RFM) calculated?

  Sum of RAMs of all atoms in the formula
• What is the relative formula mass of CaF2?

  78
• What is the relative formula mass of C6H12O6?

  180
• Why do carbon dioxide and water escape from the test tube in the reaction?

  They are both gases
• How do you calculate the mean mass of magnesium produced from the experiment?

  (3.3 + 3.5 + 3.2) / 3 = 3.3
• How can you increase the precision of the results in the experiment?

  Measure to more decimal places
• What is Avogadro's constant?

  1. 02 x 10^23
• What does Avogadro's constant represent?

  Number of atoms, molecules, or ions in a mole
• What is the formula linking mass, molecular mass, and moles?

  Mass = Mr x Moles
• What is the mass of 20 moles of calcium carbonate (CaCO3)?

  2000 g
• How do you calculate the amount of carbon dioxide in moles from 0.32 g?

  Moles = Mass / Mr = 0.32 / 44
• How do you calculate the mass of nitrogen needed to form 6.8 tonnes of ammonia?

  5600000 g = 5.6 tonnes
• What is a limiting reactant in a chemical reaction?

  The reactant that is completely used up
• How do you calculate the grams of oxygen from 40.8 g of hydrogen peroxide?

  Mass of oxygen = 19.2 g
• What are the two formulas linking concentration, mass, and volume?

  • Concentration (g per dm³) = Mass (g) / Volume (dm³)
  • Concentration (mol per dm³) = Number of moles / Volume (dm³)
• What is the concentration of the potassium hydroxide solution that neutralized nitric acid?

  To be calculated based on given data
• How many moles are in 40.8 g of a substance with a molar mass of 34 g/mol?

  1. 2 moles
• What is the mole ratio of H2O2 to O2 in the balanced equation?

  1. 1
• If there are 1.2 moles of H2O2, how many moles of O2 are produced?

  0.6 moles
• What is the mass of oxygen produced from 0.6 moles of O2?

  19.2 g
• What are the two formulae linking concentration, mass, and volume?

  • Concentration (g per dm³) = Mass (g) / Volume (dm³)
  • Concentration (mol per dm³) = Number of moles / Volume (dm³)
• What volume of potassium hydroxide solution neutralized 25.0 cm³ of nitric acid?

  31.0 cm³
• What is the balanced equation for the reaction between HNO3 and KOH?

  HNO3 + KOH → KNO3 + H2O
• How do you calculate the moles of HNO3 used in the reaction?

  Concentration x volume
• What is the number of moles of HNO3 used if the concentration is 2.0 mol/dm³ and the volume is 25.0 cm³?

  0.05 moles
• How many moles of KOH are produced if the ratio is 1:1 with HNO3?

  0.05 moles
• How do you calculate the concentration of KOH?

  Volume = Moles / Concentration
• What is the concentration of KOH if there are 0.05 moles and the volume is 0.031 dm³?

  1. 61 mol/dm³
• What is the molar volume of a gas at room temperature and pressure?

  24 dm³
• What is titration?

  A technique to find solution concentration
• What are the steps to conduct a titration?

  1. Rinse pipette with unknown solution.
  2. Measure known volume of unknown solution.
  3. Add an indicator.
  4. Rinse burette with known concentration solution.
  5. Gradually add known solution until endpoint.
  6. Record the volume added.
  7. Ensure concordant results.
  8. Perform calculations for concentration.
• Why might the theoretical amount of product not be obtained in a reaction?

  Reactions may not go to completion
• How is the percentage yield of a product calculated?

  % Yield = (Actual mass of product / Maximum theoretical mass of product) x 100%
• What is the % yield of NH3 if 40.5 g is produced from 20.0 mol H2?

  17.8%
• What is the balanced equation for the production of NH3 from N2 and H2?

  N2 + 3 H2 → 2 NH3
• How do you calculate the theoretical amount of NH3 from 20.0 mol H2?

  13.3 moles