Flashcards in this deck (49)

• What are potential errors in using a gas syringe?

  • Gas escapes before bung inserted
  • Syringe sticks
  • Some gases are soluble in water
  chemistry gas_syringe errors
• What must be noted when recording gas volume?

  • Temperature of the room
  • Pressure of the room
  chemistry gas_volume recording
• What is the ideal gas equation?

  PV = nRT
  chemistry gas_equation ideal_gas
• What is the molar gas volume at room temperature and pressure?

  1 mol gas = 24 dm³
  chemistry gas_volume molar_gas
• How can gas volumes be measured over water?

  Using an up-turned measuring cylinder in a trough of water
  chemistry gas_volume measurement
• What safety precautions should be taken with irritants?

  Wear goggles
  chemistry safety irritants
• What should be done with corrosive substances?

  Wear goggles
  chemistry safety corrosive
• What is the first step in the detailed method for measuring gas?

  Measure 30 cm³ of 1 mol dm⁻³ ethanoic acid
  chemistry method gas_measurement
• What is the final step of the gas measurement method?

  Repeat the experiment increasing mass of calcium carbonate by 0.05 g each time
  chemistry method repetition
• What is the purpose of using a gas syringe in experiments?

  To measure the volume of gas and calculate moles or reaction rates
  chemistry gas_syringe experiments
• What is the formula to calculate moles from gas volume?

  moles = PV/RT
  chemistry gas_calculation moles
• What mass of calcium carbonate is used in the detailed method?

  Approximately 0.05 g
  chemistry method calcium_carbonate
• How is the Mr of a volatile liquid calculated?

  Mr = mass/moles
  chemistry molar_mass volatile_liquid
• What is the calculated Mr of a volatile liquid if 0.150 g is injected?

  53.4 g mol⁻¹
  chemistry molar_mass volatile_liquid
• What is the volume of gas measured in the example provided?

  80 cm³
  chemistry gas_volume example
• What is the pressure in the example given?

  100 kPa
  chemistry pressure example
• What is the temperature in the example given?

  70°C
  chemistry temperature example
• What is the mass of CaCO3 used in the core practical?

  0.25 g
  chemistry core_practical calcium_carbonate
• How are moles of CO2 calculated from moles of CaCO3?

  Assume moles of CO2 = moles of CaCO3
  chemistry moles co2
• What is the formula for molar volume of CO2?

  Molar volume of CO2 = volume of CO2 / moles of CO2
  chemistry gas_laws
• What happens to calcium sulphate crystals when heated?

  CaSO4.xH2O(s) → CaSO4(s) + xH2O(g)
  chemistry decomposition
• What is the first step in the method for heating calcium sulphate?

  Weigh an empty clean dry crucible and lid.
  chemistry methodology
• What should be added to the crucible for the experiment?

  Add 2g of hydrated calcium sulphate to the crucible.
  chemistry methodology
• Why should small amounts of solid (like 0.100 g) not be used?

  Percentage uncertainties in weighing will be too high.
  chemistry uncertainty
• Why should large amounts (like 50g) of hydrated calcium sulphate not be used?

  Decomposition is likely to be incomplete.
  chemistry uncertainty
• What is the purpose of the lid on the crucible during heating?

  Prevents loss of solid but should be loose fitting to allow gas to escape.
  chemistry methodology
• What is the consequence of using a wet crucible?

  It would cause mass loss to be too large due to water loss when heating.
  chemistry methodology
• What can the heating method be used for besides calcium sulphate?

  Measuring mass loss in various thermal decomposition reactions.
  chemistry applications
• What was the mass of hydrated zinc sulphate before heating?

  3.51 g of hydrated zinc sulphate.
  chemistry calculations
• What was the mass of anhydrous zinc sulphate obtained?

  1.97 g of anhydrous zinc sulphate.
  chemistry calculations
• How do you calculate the mass of H2O lost?

  Mass of H2O = 3.51 g - 1.97 g = 1.54 g.
  chemistry calculations
• How do you calculate the moles of ZnSO4?

  Moles of ZnSO4 = 1.97 / 161.5.
  chemistry calculations
• How do you calculate the moles of H2O?

  Moles of H2O = 1.54 / 18.
  chemistry calculations
• What is the ratio of moles of ZnSO4 to H2O?

  Ratio = 0.0122 / 0.085 = 1 / 7.
  chemistry calculations
• What is the value of x in ZnSO4.xH2O?

  X = 7.
  chemistry calculations
• What is the first step in making a solution?

  Weigh the sample bottle containing the required mass of solid on a 2 dp balance.
  chemistry solution_preparation
• What should be done after adding distilled water to the beaker?

  Stir to help dissolve the solid.
  chemistry solution_preparation
• What should be done if the substance does not dissolve well in cold water?

  Heat the beaker gently until all the solid has dissolved.
  chemistry solution_preparation
• What is the purpose of rinsing the beaker and funnel?

  To ensure all solid is transferred to the volumetric flask.
  chemistry solution_preparation
• How should the volumetric flask be filled?

  Fill so the bottom of the meniscus sits on the line on the neck of the flask.
  chemistry solution_preparation
• What should not be done with a volumetric flask?

  Do not heat or put hot solutions in the volumetric flask.
  chemistry solution_preparation
• What is the advantage of using a volumetric pipette?

  It is more accurate than a measuring cylinder due to smaller uncertainty.
  chemistry measurement
• What is the first step in diluting a solution?

  Pipette 25cm3 of original solution into a 250cm3 volumetric flask.
  chemistry dilutions
• What should be done after pipetting the original solution?

  Make up to the mark with distilled water using a dropping pipette for last few drops.
  chemistry dilutions
• What is the core practical for making a volumetric solution?

  Carry out a simple acid–base titration.
  chemistry practical
• What is the best method for measuring mass in experiments?

  Measure mass on 2 or 3 d.p. balance of a weighing bottle.
  chemistry measurement
• What is a simple acid-base titration?

  A quantitative chemical analysis method to determine the concentration of an acid or base by neutralizing it with a base or acid of known concentration.
  chemistry titration
• What is the best method for measuring mass in experiments?

  Measure mass on a 2 or 3 d.p. balance of a weighing bottle.
  science measurement
• How many decimal places should the balance measure mass to?

  2 or 3 decimal places (d.p.).
  science measurement