1.2 Amounts of substance Part 1 Flashcards
What is relative atomic mass Ar
The weighted average mass of all the isotopes relative to 1/12th the mass of an atom o C-12
How do you calculate relative atomic mass
Ar = E (Mass x Abundence of each isotope) / Total abundence
What is relative molecular mass, Mr
The mass of a molcules of the compound relative to 1/12th of the mass of an atom of C-12
What is relative formular mass
The mass one one formular unit of an ionic compound relative to 1/ 12th the mass of an atom of C-12
What is the mole
The amount of substance the contains as many particles as there are in exactly 12g of C-12
This number is Avogadros constant - 6.02 x 10^23
What is molar mass
A mole of any substance conatins the same number of particles as a mole of any other substance
The mass of one mole of a substance is its Mr in grams - Its molar mass
What do you need to know to calculate moles of a substance
-Its mass if its a solid
-Its volume if its a gas
-Its volume and concentration if its a solution
How do you calulate moles
Moles (n) = Mass (g) / Mr
How do you calculate the number of atoms in a given mass
Calc its moles
Calc number of atoms
Atoms = n x Avogadros constant
How do you calculate number of moles in a solution
Need to know its
Volume in dm3
Concentration in moldm3
What is concentration
The number of moles of solute dissolved in one dm3 of solution
How do you calc moles from V and C
moles = V(dm3) x C (moldm3)
What assumptions are made wehn using the ideal gas equation
-No intermolecular forces between the molecules
-Volume occupied by the molecules is enterily negligible relative to the volume of the container
What is the ideal gas equation
PV = nRT
Pressure (Pa)
Volume ( m3)
Temperature (K)
How do you calculate density
Density = Mass / Vol
