Chemistry - Topic 2 - Amount of substances

• The mole is a way of measuring the amount of substance in chemistry
• Mole


  One mole of any substance contains 6.02 * 10^23 atoms or molecules
• Avogadro's number

  6.02 * 10^23
• Calculating number of particles

  Avogadro's number * number of moles
• Mass and Mr/Ar


  Number of moles = mass (in grams) / Mr (molecular mass) or Ar (atomic mass)
• Look for two of the components (moles, mass, Mr/Ar) in the question to use the formula
• Solutions


  Number of moles = concentration (mol/dm^3) * volume (dm^3)
• Convert volume from cm^3 to dm^3 by dividing by 1000 or multiplying by 10^-3
• Ideal gas equation


  PV = nRT
• Ideal gas equation


  • P = pressure (Pa), V = volume (m^3), n = moles, R = gas constant (8.31 J/mol·K), T = temperature (K)
• Rearranging ideal gas equation


  V = nRT/P
• Standard conditions are 298 K and 100 kPa
• Unit conversions


  m to dm: multiply by 10

  dm to cm: multiply by 100

  m^3 to cm^3: multiply by 1,000,000
• For each dimension added, multiply by 100