4: Period 3 Flashcards
Suggest why sodium oxide forms a solution with a higher pH than the solution formed from magnesium oxide.
The oxide ions react with water to form OH- alkaline ions. NaOH is more soluble than Mg(OH)2
Phosphorus burns in air to form phosphorus oxide. Give an equation.
4P + 5O2 -> P4O10
Give an equation for the reaction between phosphorus oxide and water.
P4O10 + 6H2O -> 4H3PO4
Give 2 equations to show how vanadium(V) oxide acts as a catalyst in the contact process.
V2O5 + SO2 → V2O4 + SO3
V2O4 + 0.5O2 → V2O5
Give an equation for the reaction of sodium with water.
2Na + 2H2O -> 2NaOH + H2
Why is sodium more reactive than magnesium?
It takes less energy to lose one outer electron than 2.
Describe the reaction with sodium and water.
Vigorous
Give an equation for the reaction with magnesium and water.
Mg + 2H2O -> Mg(OH)2 + H2
Give an equation for the reaction of Mg with Steam.
Mg + H2O (g) -> MgO + H2
Give an equation for the reaction of Na with O2.
2Na + 0.5O2 -> Na2O
Give an equation for the reaction of Mg with O2.
Mg + 0.5O2 -> MgO
Give an equation for the reaction of Al with O2.
2Al + 1.5O2 -> Al2O3
Give an equation for the reaction of Si with O2.
Si + O2 -> SiO2
Give an equation for reaction of P with O2.
P4 + 5O2 -> P4O10
Give an equation for the reaction of S with O2.
S + O2 -> SO2
Give the oxidation state of S in SO2.
+4
Give the conditions needed to form SO3.
Give the oxidation state of S in SO3.
High temperature and catalyst.
Oxidation state of S is +6
Describe the reaction of Na and O2 in air and give the flame colour produced when Na2O is burnt.
Vigorous
Yellow flame
Describe the reaction of Mg and O2 in air and give the flame colour produced when MgO is burnt.
Vigorous
Brilliant white flame
Describe the reaction of Al and O2 in air and give the flame colour produced when Al2O3 is burnt.
Slow reaction
No flame colour
Describe the reaction of Si and O2 in air and give the flame colour produced when SiO2 is burnt.
Slow reaction
No flame colour
Describe the reaction of P and O2 in air and give the flame colour produced when P4O10 is burnt.
Spontaneously combusts
Brilliant white flame
Describe the reaction of S and O2 in air and give the flame colour produced when SO2 is burnt.
Burns steadily
Blue flame
Which period 3 oxide has the highest melting point?
MgO
Explain why MgO has a higher melting point than Na2O.
Mg forms 2+ ions. They have a higher charge than Na+ ions, therefore they form stronger ionic bonds that require more energy to be overcome.
Explain why Al2O3 has a lower melting point than MgO.
Explain how this makes Al2O3 partially covalent.
The difference in electronegativity between Al and O is lower than the difference between Mg and O. This means that O2- ions in Al2O3 can’t attract the electrons in the metal-oxygen bond as strongly.
Explain why SiO2 has a high melting point.
It is macromolecular, so all bonds are covalent, which are very strong so require lots of energy to be overcome.
Explain why P4O10 and SO2 have low melting points.
They have a simple covalent structure so VDW and permanent dipole-dipole forces require little energy to be overcome.
What do ionic oxides do in water and what do they form?
They dissolve in water and accept protons to form hydroxide ions.
When simple covalent oxides dissolve in water, what do they form?
What is formed when they dissociate in solution?
Acidic solutions
When they dissociate in solution, a conjugate base is formed.
Give an equation for the reaction of P4O10 with water to form an acid.
Name the acid formed.
P4O10 + 6H2O -> 4H3PO
Phosphoric acid
Give an equation for the reaction of SO2 with water to form an acid.
Name the acid formed.
SO2 + H2O -> H2SO3
Sulfurous acid
Give an equation for the reaction of SO3 with water to form an acid.
Name the acid formed.
SO3 + H2O -> H2SO4
Sulfuric acid
Give an equation to show the dissociation of H3PO4 in water.
H3PO4 -> 3H+ + PO4 3-
Give an equation to show the dissociation of H2SO3 in water.
H2SO3 -> 2H+ + SO3 2-
Give an equation to show the dissociation of H2SO4 in water.
H2SO4 -> 2H+ + SO4 2-
Why are giant covalent molecules such as SiO2 classed as acids despite being insoluble in water?
They react with bases.
Why is Al2O3 insoluble in water?
Partially ionic and partially covalent
Give an equation to show the reaction of Na2O with HCl.
Na2O + 2HCl -> 2NaCl + H2O
Give an equation to show the reaction of MgO with H2SO4.
MgO + H2SO4 -> MgSO4 + H2O
What do Na2O and MgO do to acids?
They neutralise them.
Give an equation for SiO2 and 2NaOH.
SiO2 + 2NaOH -> Na2SiO3 + H2O
Give an equation for P4O10 and 12NaOH.
P4O10 + 12NaOH -> 4Na3PO4 + 6H2O
Give an equation for SO2 and 2NaOH.
SO2 + 2NaOH -> Na2SO3 + H2O
Give an equation for SO2 and 2NaOH.
SO2 + 2NaOH -> Na2SO3 + H2O
Give an equation for SO3 and 2NaOH.
SO3 + 2NaOH -> Na2SO4
What do SiO2, P4O10 and SO2/SO3 do to bases?
Neutralise them
What does Al2O3 do to acids and bases?
Neutralises them
What is formed when Al2O3 reacts with acids and bases?
Salts
Give an equation for the reaction of Al2O3 with 3H2SO4.
Al2O3 + 3H2SO4 -> Al2(SO4)3 + 3H2O
Give an equation for the reaction of Al2O3 with 3H2O and 2NaOH.
Al2O3 + 2NaOH + 3H2O -> 2NaAl(OH)4