Quantitive Chemistry Flashcards
RFM =
Relative Formula Mass
What is RFM?
Relative atomic mass of all the elements in a compound added together
What is % mass of an element in a compound?
How much of a compound is made up by a particular element
% mass of an element in a compound =
RFM of the compound
How many particles in one mole?
6.02 x 10^23
Mass =
Mr x Moles
Mr =
Mass ÷ Moles
Moles =
Mass ÷ Mr
What is meant by the conservation of mass?
No atoms are gained or lost during a reaction (destroyed or created)
What is a limiting reactant?
The reactant that is used up, stopping a reaction and leaving any other reactant in excess
Gas volume in dm3 =
Moles of gas x 24
Gas volume in cm3 =
Moles of gas x 24,000
No. of moles (using gas volume in dm3) =
Volume ÷ 24 dm3
No. of moles (using gas volume in cm3) =
Volume ÷ 24,000 cm3
What is concentration?
The amount of substance in a certain volume of a solution
What is the measurement of concentration?
mol/dm3 or g/dm3
Moles =
concentration
Concentration x Volume
Concentration =
Mass of solute(g) ÷ Volume of solvent(dm3)
Number of moles of solute(mol) ÷ Volume of solvent(dm3)
What is atom economy?
The amount of starting material that ends up as useful product and how much ends up as waste
Atom Economy =
Relative formula mass of desired product
————————————————————- x 100
Relative formula mass of all reactants
How could you improve atom economy?
Find a desirable use for the wasteful products so the reaction give useful ‘byproducts’
What is yield?
A measure of the ACTUAL amount of product formed
Percentage Yield =
Mass of product ACTUALLY made
————————————————————– x 100
Maximum THEORETICAL mass of product
Why may reactions not produce 100% yield?
The reaction was reversible - not all reactants react to make the product
The reaction didn’t finish
The reaction produced other products - side reaction such as reacting with gases in air or impurities in mixture
Lost product when separated from the reaction material - lost when filtering or transferring between containers etc.
