define mole
SI unit for amount of something
1 mole contains how many entities
6.023 * 10^23
Example of entites
Ions, atoms, molceules, formula units
Formula units
Smallest repeating ratio in lattice of ionic compounds
All number o fmole Fomrula
n = mass/molar mass
n = vol/22.7
n = no. of entites/6.023*10^23
Avagadro’s constant
6.023*10^23
Molar volume at stp
22.7
Relative formula mass
Same as relative molecular mass, but specific for ionic compounds
SI unit of relative formula mass
No unit
Emeprcial formla definations
represents the simplest whole-number ratio of atoms of each element in a chemical compound
Molecular formula equation
n * emperical formula
where n = mass of molecular formula/mass of emperical formula
Hydrated salt, and how to calcultae moleuclar mass of hydrates salt
Salt whcih contaisn water of crystalisation
to find molecualr mass, add atomic mass of elemtns in salt and then add molar mass of water multiplied by number of water molecules present
Water of crystalisation
losely combined water present in crystals of solid
How to find emeprical formual from combustion analysis
Find no of moles of CO2 and H2O formed, then find number of moles of C (same as no. of moles of CO2) and no. of moles of H (2 * H2O moles).
Then use emperical formula calculation to find it
How to find limitng regant
Find no. of moles of eevery reactant
divide by stoichiometric coeffieicnt in balanced equation
the smaller this value is the one which is the limiting reagent, and is the one that should be used to find mass/volume/mole of product formed
Percentgae yeild formula
% yeild = Experimental yeild/Theoretical yeild * 100
Percentage purity formula
mass of pure compound/total mass of compound * 100
Atom economy
Measure of efficiecnyc in green chemsitry
% ATOM ECONOMY FORMULA
Molar Mass of desired product/molar mass of all reatcnats * 100
Concentration formula
Conc = no. of moles/vol
vol in dm^3
Solution dilution formula
c1V1 = c2V2
Percentage composition formula
% element = (mass of element * no. of molecules)/molar mass of compound * 100
Back titration steps
Titrate an unknown moles of base B with known Acid in excess. Titrate unknwon acid with a differet known baseto find moles of new base added and henc efinding the moles of leftover acid present.
Then we can find moles of acid reacted in first titration used by doing starting moles - leftover moles
then by comparing raitios and stoichiometry, we can find no. of moles of known base B used
Avagadro’s gas low and formula
Euqla volumes of all gases measured under same pressure and temp coditions contail equal number of moles.
V1/V2 = n1/n2
