Equations Flashcards
Mr / Relative Formula Mass
The sum of all the Ar (atomic masses) in the compound
Percentage Yield =
Actual yield (g) / theoretical yield (g) x 100
Mass of product formed (step-by-step)
1) Write the balanced equations
2) Work out the relative formula mass (Mr) of the reactant and the product you’re interested in
3) Find how many moles there are of the substance you know the mass of
4) Use the balanced equation to work out how many moles there are of the other substance
5) Use the number of moles to calculate the mass
Steps for finding the Empirical Formula (from Masses or Percentages)
1) List all of the elements in the compound
2) underneath write their experimental masses
3) Find the number of moles by dividing each mass by the Ar for the element
4) Turn each number into a ratio by dividing them by the smallest number
5) Get the ratio in its simplest whole number form
Concentration (of a solution) =
Number of moles / Volume of solution (dm^3)
Avagrado’s Law:
One mole of any gas at room temperature occupies 24 dm^3
Solubility =
mass of solid (g) / mass of water removed (g) x 100
Volume (dm^3) =
Moles of gas x 24
24 (dm^3) = x (cm^3)
Find x:
x = 24 000 (cm^3)
Moles, Mass and RFM/Mr
Moles = Mass (g) / Mr
Percentage of Oxygen in the air (iron wool experiment):
(Start volume - Final volume) / Start Volume x 100
Acid + Metal ->
Acid + Metal -> Salt + Hydrogen
Metal + Water ->
Metal + Water -> Metal Hydroxide + Hydrogen
Less Reactive Metal + Steam ->
Less Reactive Metal + Steam -> Metal Oxide + Hydrogen
Equation for Rusting?
Iron + Oxygen + Water -> Hydrated iron (III) oxide (Rust)
