Amount Of Substance 2.3.1 Flashcards
Avogadros constant
6.02 x 10^23
Number of moles equations
n = mass/molar mass
Molecular formulae examples
The number of atoms of each element.
Molecules:
Never - N2
Have - H2
Fear - F2
Of - O2
Ice - I2
Cloudy - Cl2
Broth - Br2
Honourable mentions: P4 and S8
Empirical formula
The simplest whole number ratio of atoms of each elements in a compound
Water of crystallisation
compounds can form crystals which have water as part of their structure
Converting between moles and solution volumes
N = C x V
Molar gas volume equation
At RTP
n = V (dm3) / 24.0
n = V (cm3) / 24000
What assumptions do you have to make about the ideal gas equation?
- Random motion
- Elastic collisions
- Negligible size
- No intermolecular forces
Ideal gas equation
pV = nRT
p = Pressure (Pa)
V = volume (m3)
n = amount of gas mole
R = ideal gas constant 8.31 J mol-1 K-1
T = temperature (K)
Ideal gas conversions
cm3 to m3 x10^-6
dm3 to m3 x 10^-3
•C to K. + 273
kPa to Pa. x10^3
Percentage yield
actual yield(g)/ theoretical yield(g) x100
- actual yield obtained from a reaction is usually lower than theoritical
- theoritical yield is the maximum possible amount of products
Limiting reagent
Reactant that is not in excess and will be completely used up first and stop the reaction
What are qualities of reactions with high atom economies?
- Produces a large proportion of desired products and minimal waste products
- Important for sustainability as they make use of raw materials which are renewable and will never run out.
Atom economy equation
atom economy = sum of molar masses of desired products/ sum of molar masses of products x100
Concordant titres
Titres that agree within 0.1cm3
