2.1 Flashcards
definition of an ISOTOPE
Atoms of the SAME ELEMENT with same number of protons but DIFFERENT number of NEUTRONS
definition of RELATIVE ISOTOPIC MASS
Mass of an isotope relative to 1/12th of the mass of an atom of CARBON-12
definition of RELATIVE ATOMIC MASS
The weighted mean mass of an element to 1/12th the mass of an atom of CARBON-12
how many atoms are in 1 mol?
1 mol = 6.02 x 10 to the 23 atoms
Number of moles = ?
Moles = mass ➗ M (gmol-1)
Concentration = ?
Conc = moles ➗ volume (dm3)
Moles of gas = ?
Moles = volume ➗ 24
Ideal gas equation
pV = nRT
Pa,m3 = mol,8.31,K
0 degrees = 273 K
Assume: random motion, elastic collisions, negligible size, no IM forces
% yield = ?
% yield = actual yield ➗ theoretical yield
x100%
Stoichiometry = ?
Ratios in an equation
e.g. 2H2 + O2 -> 2H2O = 2:1 ratio
Atom economy = ?
Atom economy = sum of M of DESIRED products ➗ sum of M of ALL products
DESIRED ➗ ALL
Strong acids
e.g. HCl
Fully dissociate
HCl (aq) -> H+ (aq) + Cl- (aq)
Weak acids
e.g. CH3COOH
Partially dissociate
CH3COOH (aq) <> H+ (aq) + CH3COOH- (aq)
Alkali = ?
Base that dissolves in water (releasing OH-)
Base = ?
Neutralises acid to form a salt
Dissociation in sulfuric acid
- H2SO4 -> H+ (aq) + HSO4- (aq)
2.
HSO4- (aq) <> H+ (aq) + SO42- (aq)
First behaves as a strong acid, HSO4- ions behave as weak acid
Neutralisation
Acid+base -> salt+water
e.g. HCl + NaOH -> NaCl + H2O
Ionic: H+ (aq) + OH- (aq) -> H2O (l)
Acid+carbonate -> salt+water+CO2
Acid-base titrations
- Rough titration
- Mean titre (within 0.1cm3)
For:
Finding concentration of a solutions
Finding the purity of a substance
Identification of unknown chemicals
Redox
Oxidation is loss of electrons
Reduction is gain of electrons
Oxidation = High oxidation no. Reduction = Low oxidation no.
Oxidation numbers
Oxidation no. =
- always 0 for elements in standard state
- +2,+3 etc for ions
Sum of oxidation numbers = total charge
If oxidised=reducing agent
If reduced=oxidising agent
