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Quantitative Chemistry - Coggle Diagram
Quantitative Chemistry
Relative Formula Mass
Mr of compound is Ar of all atoms added
% mass of element in compound
(Ar x number of atoms of that element / Mr of compound) x 100
Moles
1 Mole = 6.02 x 10^23 particles
moles = mass (g) / Mr
1 mole of a substance = Mr in grams
Conservation of Mass
In a chemical reaction, mass is always conserved
no atoms destroyed
no atoms created
Mass increases
a reactant is gas
Before
cannot account for mass
After
when gas reacts
becomes part of contents
total mass increases
Mass decreases
a product is gas
Before
reactants contained
After
gas escapes
can’t account for mass
total mass decreases
Limiting Reactants
Excess
ensure all of other reactant is used
left over
Limiting
completely used up
limits amount of product that is formed
Amount of product formed is directly proportional to amount of limiting reactant
Concentration Calculations
amount of solute dissolved in a volume of solvent to make a solution
Solute
being dissolved
Solvent
does the dissolving
Solution
solute + solvent
dm³
volumes in concentration
1 dm³ = 1000 cm³
1 dm³ = 1L
concentration = no. of moles / volume
mol/dm³
x Mr
g/dm³
Gases and Solutions
Volume of Gas (dm³) = (mass (g) / Mr) x24
Same temp and pressure
equal number of moles of any gas occupy same volume
Concentration
conc (g/dm³) = mass (g) / volume (dm³)
conc (mol/dm³) = no. of moles / volume (dm³)
more solute = more concentrated
Atom economy
how much of mass of reactants is wasted and useful
= (RFM of useful products / RFM of all reactants ) x100
100%
all atoms turned into useful (desired) products
Environmental Concerns
Low atom economy
use up resources quickly
makes waste material that have to be disposed
unsustainable
unprofitable
Find use for waste products
useful ‘by-products’
Highest atom economy
one product
Percentage Yield
= (mass of product actually made / maximum theoretical mass) x100
Always less than 100%
Reactants aren’t fully used up
Side reactions
react differently than expected
Impurities in reactants
Some product is lost