C4 Stoichiometry Flashcards
Relative atomic mass
Average mass of naturally occurring atoms of an element on a scale where the ¹²C atom has a mass of exactly 12 units
molecular formula
A compound is defined as the number and type of different atoms in one molecule
relative molecular mass
the sum of the relative atomic masses. Relative formula mass, Mᵣ is used for ionic compounds
relative formula mass
Mᵣ, is used for ionic compounds
Mole
6.02x10²³
is called Avogadro’s constant or a mole.
conversion
convert 4g/cm³ to g/dm³
convert 4000g/cm³ to mol/cm³
1000cm³ = 1dm³
4g/cm³ x 1000=
4000g/dm³
4000g/cm³ / Mr
What is the formula of
number of moles (from mass and Mr)
n=m/Mr
number of moles (N)= Mass (M)/ relative molecular mass (Mᵣ)
What is the formula of volume from number of moles and Vm (Molar Gas Volume)
n=m/Mᵣ
number of moles (N)= Mass (M)/ relative molecular mass (Mᵣ)
Example Question:
Find out the mass of hydrogen
Hydrogen (H₂)
Ar= H:1
Number of moles: 3x10⁸
N= v/Vm
or
N= v/24
(at room temperature pressure)
Example Question:
Find out the mass of hydrogen
Hydrogen (H₂)
Ar= H:1
Number of moles: 3x10⁸
N=m/Mr
Ar= 2x1=2
3x10⁸=M/2
3x10⁸ x 2
=6x10⁸
Example question:
find out the number of moles in Ammonia
ammonia (NH₃)
Ar= H: 1, N: 14
mass= 3.4x10⁹
N=m/Mr
Ar= (3x1)+14=17
3.4x10⁹/17
=2.8x10⁸ moles
what is a limiting reactant
the reactant that is used up first
what is the equation that relates number of moles, volume and concentration
number of moles= volume x concentration
what is the equation that relates number of moles, mass and relative atomic mass
number of moles= mass/relative atomic mass
how many cm³ are there in 1 dm³
1000cm³= 1 dm³
