Amount of substance

• Moles


  Unit of measurement for the amount of a substance
• Mr


  Relative molecular mass
• 6.0231023 particles in 1 mole
• Moles


  Concentration of a substance
• Calculating moles


  Moles = concentration x volume/1000
• Mol/dm


  Unit of molar concentration
• Molar


  Relating to the amount of a substance in moles
• 24 dm = 1 mole
• Pressure


  Force per unit area
• Pressure


  • 10 kPa = 10,000 Pa
  • 37 kPa = 37,000 Pa
  • 476 kPa = 476,000 Pa
• Atom economy


  Mass of desired product / mass of total product * 100
• Relative atomic mass


  Average molecular mass / mass of one atom of an element
• n = number of particles
• Moles = n/avagadro’s constant
• Empirical formula 


  MARF
• Moles= mass/mr
• % yield = actual yield/ theoretical yield
• What is the symbol for amount of substance?

  n
• What is the unit used to measure amount of substance?

  Mole
• What does the Avogadro constant represent?

  The number of atoms per mole of the carbon-12 isotope
• How do you calculate the mass of 1 mole of an element?

  Mass of 1 mole = relative atomic mass in grams
• How do you calculate moles when mass and molar mass are given?

  Moles (mol) = mass (g) / molar mass (g mol-1)
• What is Avogadro’s law?

  Under the same temperature and pressure, one mole of any gas would occupy the same volume.
• What are the ideal ways in which gases behave?

  • They are in continuous motion
  • No intermolecular forces experienced
  • Exert pressure when they collide with each other or container
  • No kinetic energy is lost in the collisions
  • When temperature increases, kinetic energy of gases also increases
• What is the ideal gas equation in symbols?

  pV = nRT
• What do the symbols in the ideal gas equation represent?

  Pressure (Pa) x volume (m3) = number of moles (mol) x gas constant (8.314 J mol-1) x temperature (K)
• How many pascal is 1 atmospheric pressure equal to?

  1 atm = 101325 Pa
• What is 0℃ in kelvin?

  273 K
• What does the concentration of a solution mean?

  It is the amount of solute dissolved in 1 dm³ of solvent
• How do you calculate moles when concentration and volume are given?

  Moles (mol) = concentration (mol dm-3) x volume (dm3)
• What is a standard solution?

  A solution of known concentration
• What are the steps to prepare a standard solution?

  1. Weigh the solute using the weigh by difference method
  2. In a beaker dissolve the solute using the solvent
  3. Pour the solution into a volumetric flask
  4. Rinse the beaker using the solution and add it to the flask
  5. Add solvent to the flask carefully until it reaches the graduation line
  6. Mix the solution thoroughly to ensure complete mixing
• What do the terms concentrated and dilute mean?

  Concentrated - large amount of solute per dm3 of solvent; Dilute - small amount of solute per dm3 of solvent
• What is a species in a chemical reaction?

  Any particle that takes part in a reaction
• What are the four common state symbols?

  1. Solid (s) 2. Liquid (l) 3. Gaseous (g) 4. Aqueous (aq)
• What does the percentage yield mean?

  The efficiency of which reactants are converted into products
• What are the reasons for not obtaining 100% yield?

  • Reaction may be at equilibrium
  • The reactants may be impure
  • Side reactions could happen
  • Reactants or products may be left behind while transferring
  • Loss of products during separation and purification
• How is percentage yield calculated?

  Percentage yield = (actual amount of product (mol) / theoretical amount of product (mol)) x 100
• What does atom economy tell us about?

  The proportion of desired products compared with all the products formed in the reaction
• How is atom economy calculated?

  Atom economy = (molecular mass of desired product / sum of the molecular masses of all products) x 100