Amount Of Substance Flashcards
1
Q
Number of particles
A
Number of moles x Avogadro’s constant (6.022x10^23)
2
Q
Mass
A
Mr x mol
3
Q
Mol
A
Conc x vol
4
Q
Ideal gas equation
A
pV = nRT
- p = Pa
- V =m^3
- n = mol
- R = J K^-1mol^-1 (given)
- T = K (°C + 273)
5
Q
Preparing standard solution
A
- calculate mass needed
- weighing boat and balance for precise mass
- tip into volumetric flask with funnel
- rinse equipment with distilled water and add
- top up to bottom of meniscus drop wise
- stopper flask turn upside down to mix
6
Q
Titration
A
- use pipette measure unknown conc solution in flask, add indicator
- fill burette with standard solution acid
- use funnel to fill burette with acid below eye level
- rough titration
- accurate titration drop wise within 2cm^3 end point
- calculate amount of acid used = titre
- repeat, at least 3 concordant results (+- 0.1)
- mean titre, no anomalous results inc
7
Q
Methyl orange
A
Red in acid
Yellow in alkali
8
Q
Phenolphthalein
A
Colourless in acid
Pink in alkali
9
Q
Mol dm^-3 ———> g dm^-3
A
x Mr
10
Q
Empirical formula
A
Simplest while number ratio of atoms of each element in a compound
11
Q
Molecular formula
A
Actual number of atoms of each element in a compound
12
Q
% yield
A
Actual yield/theoretical yield x100
Don’t use moles
13
Q
Reasons why actual yield is less than theoretical yield
A
- incomplete reaction
- lost during transfer
- left on filter paper
14
Q
% atom economy
A
Molecular mass of desired product/sum of molecular masses of all reactants x100
Use moles
15
Q
Advantages of high atom economy
A
- less waste
- more sustainable
- less expensive
