Chemistry UNIT 1- Amount of Substance Flashcards
Define relative atomic mass
The weighted average mass of an atom of an element taking into account its naturally occurring isotopes relative to 1/12th the relative atomic mass of an atom of carbon 12
Ar = Average mass of one molecule / 1/12th the mass of one atom of Carbon 12
Define Relative molecular mass
The mass of that molecule compared to 1/12th the relative atomic mass of an atom of carbon 12.
Mr = Average mass of one atom of an element / 1/12th the mass of one atom of Carbon 12
Define relative formula mass
The mass used for ionic compounds which don’t exist as molecules, still has symbol Mr
What is an entity?
General term for a particle (eg. atom) simplest formula unit of an ionic substance.
Define Avogadro’s number.
The number of atoms in 12g of carbon 12.
This is 1 mole of carbon 12.
Define the term molar mass.
The mass per mole of a substance.
How can we form a solution?
When a solute dissolves in a solvent forming a solution.
What does molecular formula show?
Shows the actual number of atoms of each element in a molecule.
(eg. C3H6O3)
What does empirical formula show?
The smallest whole number ratio of each element in the substance.
(eg. C3H6O3 = CH2O)
what units do we use for solutions?
gdm^-3 or moldm^-3
What is the equation for atom economy?
Atom economy = mass of desired product / total mass of reactants (or products) x100
What is the ideal gas equation?
PV=nRT
What is the equation to work out moles from elements or compounds?
Mol = mass / Mr
What is the equation to work out moles from solutions?
Mol = VC / 1000
V = cm^3 C = moldm^-3
How do you calculate percentage yield?
% yield = Actual mass / Theoretical mass x100
