chem paper 1 definitions Flashcards
molecular formula
the number of atoms of each element in a molecule
empirical formula
the simplist whole number ratio of atoms of each element in a compound
relative molecular mass
the mass of a molecules relative to 1/12th the mass of carbon 12
CuSO4-H2O
-H2O stands for the water of crystallisation
ionic bonding
the electrostatic attraction between positive and negatively charged ions in an ionic compound
solubility of ionic compounds
ionic compounds dissolve in polar solvents such as water.
the ionic lattice is broken down
the water molecules attract and surround the ions
factors which effect the solubility of ionic compounds
greater the electrostatic attraction between ions, greater the solubility
covalent bond
the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
metalic bonding
the strong electrostatic attraction between postive cations and delocalised electrons
qualitative analysis test order and why?
carbonate test, sulphate test then halide test
if not in this order you can get false results
barium ions can react with carbonate forming barium carbonate, white insoluble precipitate
halide test you can for AgCO3 or AgSO4
which are both white precipitates and insoluble
silver halide soluble in what type of NH3
AgCl = dilute NH3 AgBr = conc NH3 AgI = not soluble
testing for NH4+
add hydroxide ions, ammonia gas produced. warm up mixture and test gas produced with a moist pH indictor paper. paper will turn blue is positve
factors which effect rate constant
- increasing temperature
calcutlating rate from half life
K=ln2/halflife
partial pressure of (A) = ?
mole fraction of A x total pressure
Kc and Kp units respectively
moldm^3 and Kpa
what does the magnitude of an equilibrium constant indicate of a chemical equilibrium ?
k= 1 equilibrium half way
k=100 equilibrium way in favour of products
k=10^-2 equilibrium was in favour of products
when does K change?
only changes if temperature changes
if forward reaction is exothermic, and temperature increases. what happens to Kp
Kp decreases as the system is no longer in equilibrium .
equilibrium shifts to the left so reactions partial pressure increases and products partial pressure decreases
how do you calculate pH of a strong acid ?
HA——> H+ (aq) + A- (aq)
[HA] = [H+] as HA completely dissocates
Ka is used for …..
weak acid dissociation
the two Ka approximations
- [H+] equilibrium = [A-] equilibrium
[HA] start = [HA] equilibrium as the dissociation is small
what to use to find pH of strong bases
Kw equation
Kw= [H+][OH-]
