Amount Of Substance Flashcards
Calculating number of particles
Number of particles= moles x Avogadro‘s number
Relative atomic mass definition
Relative molecular mass definition
Moles equation
Miles = mass / mr
Percentage yield calculation
Actual / theoretical x 100
Atom economy
Mass of desired / total x 100
Include number before
Importance of atom economy
Reduces amount of by products
Increased mass of atoms in reactants turned into products
Concentration equation
Concentration = moles / volume
Density equation
Density = mass / volume
Steps to make a standard solution in titration
Stage one: transfer known mass of solid
Weigh the weighting boat by itself, weight the boat with the solid , and find difference
Record this value and transfer to beaker
Stage 2 :dissolve in water
Add distilled / deionised water (50cm3)
Stir with a glass rod until all the solid has been dissolved
Stage 3 = transfer , washing and agitation
Transfer to a volumetric flask using g a funnel and wan everything with deionised water
Make up 250 cm 3 with water
Shake to mix
How to improve accuracy of titration
Remove any air bubbles from burette tap
Remove the funnel
Swirl the conical flask and rinse the walls of the Conical flask with deionise water
Why would you remove any air bubbles from burette tap ?
Volume off air bubbles will be counted in burette reading
Why would you remove the funnel
Solution drops could fall from the funnel and effect burette reading
Why would you swirl the conical flask with distilled water?
Ensures all reactants mix and no reagent left as doesn’t change number of moles so no adverse effect on titration
Percentage uncertainty
Error / amount measured x 100 ( x2 by doesn’t say total )
How to reduce percentage error in titre measurements to increase measurement made from burette?
Increase concentration of solution in conical flask
Decrease concentration of solution in burette
Ideal gas equation and units
PV = NRT
P= pressure kPa (x 1000 )
V = m3 (x106 if in cm3) or (103 if in dm3)
N = mouse
R = 8.31
T = +273
Empirical formula definition
Compound with the simplest whole number ratio of atoms of each element
Molecular formula definition
Compound with the actual number of atoms of each element
How to find empirical formula
Mass
Mol
Divided smallest value
Ratio
How to find molecular formula from empirical formula
Sane steps as empirical formula but given mr to which you have to divide total mass of empirical formula with given mr to find number and times all atoms by the found number
