Amount of Substances

• Mole calculation for solids:

  mass/Mr
• Mole calculation for gas at RTP:

  volume/24
• Equation for gas at RTP:

  PV=nRT
• Mole calculation for solutions:

  concentration x volume
• The unit for Mr:

  g/mol
• The unit for mass:

  g
• The unit for concentration:

  mol/dm^3
• The unit for volume:

  dm^3
• The unit for volume in PV=nRT:

  m^3
• The unit for temperature in PV=nRT:

  K
• The unit for pressure in PV=nRT:

  Pa
• 1 ml = 1 cm^3
• 1 L = 1000 cm^3
• What is the value of R in PV=nRT?

  8.314
• 1 tonne = 10^6 grams
• 1 milligram = 1/1000 grams
• . H20 means that its a hydrated salt
• Define Hydrated salts:

  The crystals contain water
• Define Anhydrous salts:

  The crystals do not contain water
• The excess reagent's mole is the limiting reagent's mole and more

  "Can the value of the calculator go into the mole? if yes= excess, no=limiting
• State the reasons for a low percentage yield:

  • the reaction is reversible
  • some products are lost
  • other reactions have taken place
• Include MR (molar ratio) in percentage atom economy when calculating Mr
• Define the Percentage Yield:

  compares the amount produced to the amount you should get
• Define the Atom Economy:

  the proportion of the mass of all the products that is the desired product
• In a good reaction, the by-products weighs less than the desired product
• In reacting gas volumes:

  treat the volumes as ratios and find the limiting reagent

  To find left over gas: excess gas volume - reacted gas volume

  In finding the final gas volume of mixture of products:

  use the left over gas and the products
• If the empirical ratio is 1:1 use their oxidation numbers
• Always round to 3 significant figures
• If a substance is a precipitate, it's a solid state
• Formula for finding the concentration in $gdm^-3$:

  Mr x moles/ volume
• Define Relative Atomic Mass:

  The weighted mean mass of an atom of an element compared to 1/12 th of the mass of a carbon-12 atom
• When a substance is burning, add oxygen to it in the chemical equation
• Write the general formulas for the metals when undergoing thermal decomposition.

  1. metal nitrate → metal nitrate + oxygen
  2. metal nitrate → metal oxide + nitrogen dioxide + oxygen
  3. metal nitrate → metal + nitrogen dioxide + oxygen
  4. metal carbonate → metal oxide + carbon dioxide
  5. metal carbonate → metal + carbon dioxide + oxygen
  6. metal hydroxide → metal oxide + water

  
• ammonia + nitric acid → ammonium nitrate
• NH3 + HNO3 → NH4NO3
• What is the general formula for metal hydrogencarbonate ( use x as the metal):

  xHCO3
• Avogadro's constant:

  6.02 x 10^23
• Formula for finding the number of particles/ molecules:

  moles x (6.02 x 10^23)
• Formula to work out the mass of an atom:

  Mr / 6.022 x 10^23
• Formula for working out the number of atom or ions :

  ( moles x 6.02 x 10^23 ) x number of elements / atoms