blake Flashcards
sodium reacting with oxygen
observations:
4Na(s) + O2(g) -> 2Na2O(s)
- yellow flame
- white solid formed
magnesium reacting with oxygen
observations:
2Mg(s) + O2(g) -> 2MgO(s)
- bright white flame
- white solid formed
aluminium reacting with oxygen
observations:
4Al(s) + 3O2(g0 -> 2Al2O3
- white solid
silicon reacting with oxygen
observations:
Si(s) + O2(g) -> SiO2(g)
(silicon dioxide is a giant covalent compound)
- white solid
phosphorous reacting with oxygen
observations:
P4(s) + O2(g) -> P4O10
- bright white flame
- white solid formed
sulfur reacting with oxygen
observations:
S(s) +02(g) -> SO2(g)
2SO2(s) +02(g) -> 2SO3(g)
- blue flame
- colourless gas (SO2)
- colourless liquid (SO3)
MgO (ionic) melting points
high melting point as there is a higher charge so stronger electrostatic attraction. Also is smaller, so has a higher charge density
Al2O3 (ionic) melting points
ionic with “some covalent character” which lowers the melting point
SiO2 (giant covalent) melting points
strong covalent bonds must break to melt the compounds
P4O10 (simple molecular) melting points
IMF forces must be broken. it has a relatively high Mr (284), the van der waals forces are quite strong
SO2 compared with SO3 melting points
Despite SO2 having dipole-dipole forces, the melting point of SO3 is higher due to a greater Mr resulting in larger Van der Waal force between molecules
period 3 oxides + water
sodium oxide
Na2O(s) + H20(l) -> 2NaOH(aq)
pH = 14
period 3 oxides + water
magnesium oxide
MgO(s) + H2O(l) -> Mg(OH)2(s)
pH= 9
Mg(OH)2 has limited solubility
period 3 oxides + water
aluminium oxide
Al2O3(s) + H2O(l) -> does not dissolve in water
pH = 7
period 3 oxides + water
silicon oxide
SiO2(s) + H2O(l) -> does not dissolve in water
pH = 7
period 3 oxides + water
phosphorus oxide
P4O10(s) + 6H2O -> 4H3PO4(aq)
pH=0
period 3 oxides + water
sulfur dioxide
SO2(g) + H2O -> H2SO3
reversible reaction so it’s a weak acid
pH = 3
period 3 oxides + water
sulfur trioxide
SO3(g) + H2O -> H2SO4
strong acid
pH = 0
H3PO4 shape
what can it dissociate to make
tetrahedral 109.5
- H2PO4 -
- HPO4 2-
- PO4 3-
H2SO3 shape
what can it disassociate to make
pyramidal
- HSO3 -
- SO3 2-
H2SO4 shape
what can it disassociate to make
tetrahedral
- HSO4 -
- SO4 2-
what is an acid
H+/ proton donor
what is a base
proton acceptor
alkali reaction of period 3 oxides
Na20 + 2HCL
2Nacl + H20
