reacting masses

• finding masses produced in chemical reactions:

  • use the equation
  • the number of moles
  • convert to masses - mass = n x Mr
  • go to 1kg of known substance
  • go to quantity required
• balancing an equation using moles

  • masses
  • n = m/Mr
  • number of moles
  • divide by the lowest number
  • whole numbers
• Calculate the mass of silver formed when 23.2g of silver oxide is heated.

  2Ag2O -> 4Ag + O2

  2 moles of silver oxide give 4 moles of silver and therefore 2:2

  2 x 232g = 464g 4 x 108g = 432g

  464/464 = 1 432/464g

  23.2g 23.2 x 432/464 = 21.6g