quantitative chemistry

• state the steps for mole calculations

  balanced equation

  mass to moles

  find ratio of moles

  moles to mass
• what happens to mass of product if reactants react fully?

  mass of reactants will be equal to mass of product
• define uncertainty


  amount of error a measurement may have

  • random errors
  • mechanical errors
• how is uncertainty calculated?

  range/2
• state the steps for using moles to balance equations

  work out rfm of all substances

  calculate no. of moles of each substance

  convert to whole no. ratio

  balance the symbol equation
• unit for conc

  mol/ dm^3
• unit for vol

  cm^3 / 1000 = dm^3
• steps to find conc of a solution using moles

  work out moles in known substance

  use molar ratio to find moles in unknown substance

  use that no. of moles to work out conc of unkown substance
• define limiting reactant


  reactant that is used up first
• define excess reactant


  reactant left behind after limiting reactant has been used up
• define relative formula mass?


  avg mass of a compound
• what is avogadro's constant?


  6.022 x 10^23
• what are moles?


  a unit of measurements
• what is the formula to find moles?


  moles = mass/Mr
• what is the formula to find conc of a substance?

  moles = conc x vol
• what is the law of conservation of mass?


  matter cannot be created or destroyed
• what is the exception to the law of conservation of mass?


  gases may appear so, if:

  • scale did not weigh all reactants
  • gas may have escaped into surroundings
• equation for volume of gas at room temp/pressure


  • equation for volume of gas at room temp/pressurevol of gas = mol x 24
• formula for %mass of an element in a compound


  percentage = (Ar x number of atoms of element/ Mr of compound) x 100
• formula for concentration (w out moles)


  conc = mass of solute / volume of solvent (dm^3)