Period 3 Oxides

Question 1

Reaction of Na2O with water

Answer 1

Na+ and O2- ions dissolve in water then O2- ions react with water
O2- + H2O —> 2OH-

Question 2

Equation for reaction of Na2O with water and pH?

Answer 2

Na2O + H2O —> 2NaOH (aq). pH 14

Question 3

Reaction of Na2O with acid?

Answer 3

Na2O + 2H+ —> 2Na+ + H2O

Question 4

Reaction of Na2O with alkali

Answer 4

No reaction

Question 5

Nature of Na2O

Answer 5

Basic

Question 6

Reaction of MgO with water

Answer 6

Slightly soluble (some Mg2+ + O2- ions dissolve in water (less soluble than Na2O due to higher lattice enthalpy) and then the O2- ions react with water: O2- + H2O —> 2 OH-

Question 7

Equation for reaction of MgO with water and pH?

Answer 7

MgO + H2O —> Mg(OH)2 (aq). pH 10

Question 8

Reaction of MgO with acids

Answer 8

MgO + 2H+ —> Mg2+ + H2O

Question 9

Reaction of MgO with alkali

Answer 9

No reaction

Question 10

Nature of MgO

Answer 10

Basic

Question 11

Reaction of Al2O3 with water

Answer 11

Insoluble due to very high lattice enthalpy

Question 12

Reaction of Al2O3 with acids

Answer 12

Al2O3 + 6H+ —> 2Al3+ + 3H2O

Question 13

Reaction of Al2O3 with alkali

Answer 13

Al2O3 + 2OH- + 3H2O —> 2Al(OH)4-

Question 14

Nature of Al2O3

Answer 14

Amphoteric

Question 15

Reaction of SiO2 with water

Answer 15

Insoluble due to lattice of atoms linked by strong covalent bonds that would have to be broken

Question 16

Reaction of SiO2 with acid

Answer 16

No reaction

Question 17

Reaction of SiO2 with alkali

Answer 17

SiO2 + 2OH- —> SiO32- + H2O
(must be hot, concentrated NaOH)

Question 18

Nature of SiO2

Answer 18

Acidic

Question 19

Reaction of P4O10 with water

Answer 19

Reacts violently: H2O molecules attach the delta+ P atoms, leading to the release of H+ ions from the water molecules.

Question 20

Equation for reaction of P4O10 with water and pH?

Answer 20

P4O10 + 6H2O —> 4H3PO4. pH 0

Question 21

Reaction of P4O10 with acid

Answer 21

No reaction

Question 22

Reaction of P4O10 with alkali?

Answer 22

P4O10 + 12OH- —> 4PO4^3- + 6H2O

Question 23

Nature of P4O10

Answer 23

Acidic

Question 24

Reaction of SO2 with water

Answer 24

Dissolves- H2O molecules attach the delta+ S atoms, leading to the release of H+ ions from the water molecules.

Question 25

Equation for reaction of SO2 with water and pH?

Answer 25

SO2 + H2O —> H2SO3. pH 3

Question 26

Reaction of SO2 with acid

Answer 26

No reaction

Question 27

Reaction of SO2 with alkali

Answer 27

SO2 + 2OH- —> SO3^2- +H2O

Question 28

Nature of SO2

Answer 28

Acidic

Question 29

Reaction of SO3 with water

Answer 29

Reacts violently- H2O molecules attach the delta + S atoms, leading to the release of H+ ions from the water molecules.

Question 30

Equation for reaction of SO3 with water and pH?

Answer 30

SO3 + H2O —> H2SO4. pH 0

Question 31

Reaction of SO3 with acid

Answer 31

No reaction

Question 32

Nature of SO3

Answer 32

Acidic

Question 33

Reaction of SO3 with alkali

Answer 33

SO3 + 2OH- —> SO4^2- + H2O

Question 34

Reactions of ionic oxides with water?

Answer 34

Form alkaline solutions pH 10-14

Question 35

Reaction of simple covalent oxides with water?

Answer 35

Form acidic solutions with pH around 0-2

Question 36

What are the ionic oxides?

Answer 36

Na2O
MgO
AL2O3

Question 37

What are the macromolecular oxides?

Answer 37

SiO2

Question 38

What are the simple covalent oxides?

Answer 38

P4O10
SO2

Question 39

Why are metal oxides basic and non metals acidic?

Answer 39

metal oxides are ionic and release O2– ions into water
O2– ions react with water to form OH– ions making solution alkaline
non-metal oxides are usually molecular
H2O attacks the δ+ non-oxygen atom and this reaction releases H+ ions making solution acidic