OUTCOME 3 - moles + organic compounds Flashcards
(41 cards)
mass spectrometer use
a scientific instrument used to:
- Determine the relative atomic mass (Aᵣ) of an element
- Identify elements or compounds
- Find the molecular mass (Mr) of a compound
- Analyse isotope patterns
Define relative isotopic mass
The mass of an atom of the isotope relative to the mass of an atom of carbon-12 taken as 12 units exactly
Define relative atomic mass
The weighted average of the relative isotopic masses of an element
on the scale where 12C is 12 units exactly.
- symbol = Ar
Calculate relative atomic mass
Ar = (isotope1mass×%abundance) +(isotope2mass×%abundance)
DIVIDED BY 100
Define molar mass (M)
The mass of 1 mole of a substance
(measured in g mol−1).
- symbol = M
Calculate molar mass
- find atomic mass of each element
- multiply by how many atoms of each element IF given
- add them all together
example: H2O (H - m of 1) (O -m of 16)
M = (2×1)+ (1×16)
=2+16
=18g/mol
What element is used as a basis for relative atomic mass and why
Carbon 12
- stable and common
- one atom of carbon-12 is exactly 12 units of mass
Define mole (n)
The amount of substance that contains
the same number of fundamental particles as there are atoms in 12 g of carbon-12;
- symbol = n
- unit = mol.
Explain what Avogadro’s number (NA) is
the number of particles (atoms, molecules, or ions) in 1 mole of a substance
NA = 6.022 × 10²³
formula 1 (n’s)
n = N/NA
formula 2 (m’s)
n = m/M
Calculate percentage composition of elements in compounds
(Totalmassoftheelementinthe
compound / molar mass of compound) x 100
calculate empirical formula
- Write the mass or percentage of each element.
- Divide by the atomic mass (Aᵣ) to get moles.
- Divide all mole values by the smallest one.
- Write the formula using whole numbers.
Calculate molecular formula
n = molecular mass / empirical formula mass
Describe what hydrated ionic compounds are
Ionic compounds that have water molecules chemically bonded to them as part of their solid structure
Calculate the percentage composition of water in hydrated compounds
1.) Write the formula of the hydrated compound (e.g. CuSO₄·5H₂O).
2.) Find the molar mass (Mr) of the whole compound, including water.
3.) Find the mass of just the water (number of H₂O × 18)
4.) (mass of water/total molar mass) x 100
Intramolecular bonding in hydrocarbons
- bonds within a molecule
- Colavent bonds
- C and H share electrons
Intermolecular bonding in hydrocarbons
- forces between molecules
- weak (dispersion forces)
- affect BP and MP
Homologous series
group of organic compounds with:
- same functional group
- same general formula
- similar chemical properties
Saturated
compound w/ only SINGLE bonds between carbons (alkanes)
Unsaturated
A compound with at least one double bond between carbon atoms
(alkenes)
Isomers
compounds w/ same molecular formula but different structures
Alkanes
- single bonds
- saturated
- less reactive
- CnH2n+2
example: methane
Alkenes
- at least 1 double bond
- unsaturated
- more reactive
- CnH2n
example: ethene
