C3 quantitative chemistry

• What does the law of conservation of mass state?

  Mass of products equals mass of reactants
• In the reaction CuO + H2SO4 -> CuSO4 + H2O, what will appear to happen to the mass?

  The mass will stay the same
• In the reaction ZnCO3 -> ZnO + CO2, what will appear to happen to the mass?

  Mass will decrease, CO2 gas is released
• In the reaction 2Mg + O2 -> 2MgO, what will appear to happen to the mass?

  Mass will increase, oxygen gas is added
• If 24 g of magnesium reacts with 71 g of chlorine, what mass of magnesium chloride is obtained?

  95g
• If 12 g of magnesium reacts to make 47.5 g of magnesium chloride, what mass of chlorine reacts?

  35.5g
• If 100 g of calcium carbonate decomposes to give 56 g of calcium oxide, what mass of carbon dioxide is formed?

  44g
• What mass of calcium carbonate is needed to make 224 g of calcium oxide?

  400g
• What elements and how many of each are in MgBr2?

  1 magnesium, 2 bromine
• What is the relative formula mass of water?

  18
• What is the relative formula mass (M,) of KNO3?

  101
• What is the relative formula mass of sodium chloride?

  58.5
• What is the relative formula mass of oxygen?

  32
• What is the relative formula mass of calcium carbonate?

  100
• What is the relative formula mass of ammonia?

  17
• What is the formula used to calculate the number of moles?

  moles = mass / relative atomic mass
• What is the mass of one mole of oxygen atoms?

  16g
• What is the mass of one mole of oxygen gas (O2)?

  32g
• What is relative atomic mass?

  Average mass compared to 1/12th carbon-12
• What is relative formula mass?

  Average mass of molecule, compared to carbon-12
• How many particles are there in 1 mole?

  6.02 x10^23 per mole
• What is a mole?

  Amount with Avogadro's constant of particles
• What is an excess reagent?

  Reactant with more moles than needed
• What is a limiting reagent?

  Reactant with fewest moles (molar ratio considered)
• In the reaction 2KBr + F₂→ 2KF + Br2, with 2 moles of KBr and 2 moles of F2, what is the limiting reagent?


  KBr
• Why are excess reagents used in chemical reactions?

  To ensure all other reactants are used
• In the reaction 2KBr + F₂→ 2KF + Br2, with 2 moles of KBr and 2 moles of F2, what is the excess reagent?

  F2
• What is the equation to calculate % element in a compound?

  % element = (r.a.m. x number) / r.f.m. x 100
• What is concentration?

  Solute dissolved per unit of solvent
• What is the difference between concentrated and dilute solutions?

  Concentrated has more solute than dilute
• What is the equation to calculate the concentration of a solution?

  concentration = mass / volume
• If reactants A and B have masses 10g and 20g respectively, what mass of products should you expect, assuming complete reaction?

  30g