The Periodic Table Reactions

Question 1

How does NaCl react in water + and pH (for all of these flashcards)

Answer 1

Dissolves readily in water to form hydrated ions in a neutral solution

Question 2

NaCl reaction

Answer 2

NaCl(s) -> Na+(aq) + Cl-(aq)

Question 3

MgCl2 in water reaction and pH

Answer 3

Dissolves in water with partial hydrolysis (due to the high polarising power of Mg2+ ions) to give a slightly acidic solution.
pH 6.5

Question 4

Equation for MgCl2 in water, including that for partial hydrolysis

Answer 4

MgCl2 + 6H2O -> [Mg(H2O)6]2+ + 2Cl-

[Mg(H2O)6]2+ + H2O (REVERSIBLE REACTION) [Mg(H2O)5(OH)]+ + H3O+ (hydronium ions to give it its slight acidity)

Question 5

AlCl3

Answer 5

Dissolves in water with partial hydrolysis to give an acidic solution, pH 3

Question 6

AlCl3 reaction, including partial hydrolysis, and its reaction in limited water

Answer 6

AlCl3 + 6H2O -> [Al(H2O)6]3+ + 3Cl-

[Al(H2O)6]3+ + H2O (REVERSIBLE REACTION) [Al(H2O)5(OH)]2+ + H3O+

Limited cold water:
AlCl3 + 3H2O -> Al(OH)3 + 3HCl(g) (white fumes of HCl gas)

Question 7

SiCl4, PCl5

Answer 7

Dissolves in water due to complete hydrolysis to form strongly acidic solutions, pH 2

Question 8

SiCl4 reaction equation

Answer 8

SiCl4 + 2H2O -> SiO2 + 4HCl(aq)

Question 9

PCl5 reactions (excess water, limited cold water then excess water)

Answer 9

Excess water: PCl5 + 4H2O -> H3PO4 + 5HCl

Limited water (1:1 ratio with H2O): PCl5 + H2O -> POCl3(l) + 2HCl(g)
Then Excess water: POCl3 + 3H2O -> H3PO4(aq) + 3HCl(aq)

Question 10

Why is Al3+ acidic?

Answer 10

Al3+ in [Al(H2O)6]3+ has high charge density and can thus polarises the electron clouds of its surrounding water molecules, thereby weakening the O-H bonds in the water molecules which results in the release of protons

Question 11

Na2O

Answer 11

Reacts vigorously to form strongly basic solution NaOH, pH 13

Question 12

MgO (give equation) and reason

Answer 12

Reacts less vigorously to form a weakly alkaline solution due to more exothermic lattice energy. It is sparingly soluble, pH 9.

MgO(s) + H2O(l) (REVERSIBLE REACTION) Mg(OH)2 (aq)

Question 13

Al2O3 reaction with water

Answer 13

Does not react with water due to very high exothermic lattice energy, making it very difficult to break the ionic lattice structure.

Question 14

SiO2 reaction with water

Answer 14

SiO2 does not react with water due to strong and extensive covalent bonds between Si and O atoms in the lattice structure, making SiO2 insoluble in water.

Question 15

P4O10 reaction with water

Answer 15

Covalent non-metal oxides react readily with water to form acidic solution (H3PO4), pH 2

Question 16

SO3 reaction with water

Answer 16

Covalent non-metal oxides react readily with water to form acidic solution (H2SO4), pH 2

Question 17

P4O10 with water equation

Answer 17

P4O10 + 6H2O -> H3PO4

Question 18

SO3 with water equation

Answer 18

SO3 + H2O -> H2SO4

Question 19

How does the nature of oxides change across a period?

Answer 19

Basic to amphoteric to acidic.

Question 20

Reaction of Al2O3 with acids and bases (Amphoteric oxide: Ionic oxide with covalent character)

Answer 20

Al2O3(s) + 6HCl -> 2AlCl3(aq) + 3H2O
Al2O3(s) + 2NaOH + 3H2O -> 2NaAl(OH)4

Question 21

Reaction of SiO2 with base

Answer 21

SiO2 + 2NaOH (MUST BE CONC.) -> Na2SiO3 + H2O

Question 22

Reaction of P4O10 with base

Answer 22

P4O10(s) + 12NaOH(aq) -> 4Na3PO4(aq) + 6H2O(l)

Question 23

Reaction of SO3 with base

Answer 23

SO3(g) + 2NaOH(aq) -> Na2SO4(aq) + H2O

Question 24

Reaction of Al(OH)3 with acids and bases

Answer 24

1) Al(OH)3(s) + 3HCl -> AlCl3 + 3H2O
2) Al(OH)3(s) + NaOH -> NaAl(OH)4 (aq)