Chapter 3 Amount of Substance Flashcards
Avogadro constant -
6.02 x 10^23
there are this number of atoms in 12g of carbon-12
Molar Mass
Amount of moles = Mass / Moloar mass.
Molar mass the is the mass of a mole.
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How to calculate empirical formula
Convert mass into moles of atoms using
Mass/Mr = moles
To find the smallest whole number ration, divide by the smallest whole number.
Write the ratio of the elements and then write the ratio.
Relative Molecular mass definition
compares the mass of a molecule with the mass of an atom of carbon-12. You can easily calculate a relative molecular mass by adding together the relative atomic mass of the elements making up a molecule.
Relative formula mass
is the same thing as relative molecular mass but RFM is used for ionic compounds.
Equation for converting between moles and solution volumes
Number of moles = Volume(dm) x concentration(mol/dm)
Standard Solution definition
a solution of known concentration.
Equation for mass concentration
number of moles = mass(g) x concentration (g/dm)
Equation for moles and gas volumes
moles x 24 = volume
this is the case when at RTP (room temperature pressure)
The ideal gas equation
pV = nRT
pressure(pa) x Volume(m^3) = amount of gas molecules(moles) x ideal gas constant(8.31j/mol/k) x Temperature(K)
how to convert for the ideal gas equation
cm^3 -> m^3 x10^-6
dm^3 -> m^3 x10^-3
Degrees to kelvin +273
Kpa to Pa x10^3
Stoichiometry
Stoichiometry is the ratio between the elements of the reaction. The ratio is the balancing number in the reaction.
Percentage yield formula
(actual yield/theoretical yield ) x 100
Limiting reagent
The reactant that is not in excess will be completely used first and stop the reaction- it is called the limiting reagent.
Atom Economy
A measure of how well the atoms have been utilised
= (desired products/ all products) x 100
