2. Amount of Substance

• Relative Atomic Mass


  The average mass of an atom of an element, compared to that of the mass of 1/12th of the average mass of an atom of carbon-12
• Relative Molecular Mass


  The average mass of one molecule compared to 1/12th of the mass of one atom of carbon-12
• Avogadro Constant


  The number of particles in one mole of an atom: 6.022 x 10^23
• Solvent


  A liquid that can have a substance dissolved into it

  
• Solute


  A solid that can be dissolved

  
• Solution

  A solute dissolved in a solvent

  
• Ideal Gas Equation


  pV = nRT
• Concentration

  Moles / Volume Amount of substance in moles dissolved in 1dm3 of solution Mol dm-3
• Moles (mass)

  Mass / Mr
• Atom Economy


  Mr of producta/ sum of Mr of all reactants x 100
• Percentage Yield

  (actual output / predicted output) x 100
• Calculating empirical formula


  1. % by mass

  2. Divided by Ar

  3. Divide by smallest
• Calculate molecular formula


  Relative molecular mass divided by relative mass of empirical formula
• equation for amount of moles (Avogadro constant)


  amount of moles = number of particles / Avogadro constant
• 4 reasons for lack of 100% percentage yield?

  loss by mechanical transfer, loss during separating technique, unwanted side reactions, reaction not complete
• units

  1cm3 - 1ml 1dm3 - 1l 1dm3 - 1000cm3
• what is titration an example of?


  volumetric analysis
• 2 reasons why conical flasks are used in titration?


  1. can swirl reactant easily2. sloped sides ensure solution can not spill out
• what is the dilution factor? how is it calculated?


  the amount the original solution is diluted by. new total volume/ volume of original solution added
• what is the dilution factor of 25cm3 to 250cm3


  10
• what is important about the first titre?


  it should be rough and bigger than the two accurate titrations
• what is a standard solution?


  a solution of known concentration
• what should values be recorded to in a titration?

  0.05cm3
• what should two accurate titre values be?


  within 0.10cm3 of each other
• how to convert from gdm-3 to moldm-3?


  gdm-3 multiplied by Mr
• equation for percentage error?


  error of equipment/volume of solution
• what kind of titration is phenolphthalein used for?


  a strong and weak acid-strong base
• what is the colour of phenolphthalein in 3 solutions?


  acid - colourlessneutral - colourlessalkaline - pink
• what is the colour of methyl orange in 3 solutions?

  acid - redneutral - orangealkaline - yellow
• which solution goes in the conical flask?


  alkali
• which solution goes in the burette?


  acid
• what is the molar volume?


  1 mole of a gas occupies a volume of 24dm3 at room temperature and pressure
• equation for moles (gas)


  moles = volume / 24dm3
• what three factors does the ideal gas equation relate?


  1. as pressure increases, the volume of a gas decreases 2. as temperature increases, the volume of a gas increases 3. the amount of gas in moles is directly proportional to its volume
• Ideal Gas Eqaution


  pV = nRT
• How do you convert Celsius to Kelvin?


  K = C + 273
• what is volume measured in ideal gas equation?


  m3
• how to convert from m3, dm3, cm3

  1m3 = 1000dm3 = 1000000cm3
• what does percentage yield not take into account?


  any waste products
• the mole of a substance


  is the amount of that substance that contains as many particles (atoms or molecules or ions) as there are atoms of C¹² in 12g of C¹². (or Avogadro's constant)