2B Acids, Bases and Salts

Question 1

Brønsted-Lowry acid

Answer 1

A proton (H+ ion) donator

Question 2

Strong acid

Answer 2

A strong acid dissociates fully so that all the ions have separated.
H3PO4(aq) —> 3H+(aq) + PO4 3- (aq)

Question 3

Weak acid

Answer 3

A weal acid partially dissociates in solution

CH3CH2COOH (aq) ⇌ H+(aq) + CH3CH2COO- (aq)

Question 4

Brønsted-Lowry base

Answer 4

A proton (H+ ion) acceptor

Question 5

Alkali

Answer 5

a soluble base. Dissolves in water and gives off OH-

Question 6

Metal hydroxide to form an Alkali

Answer 6

Mg(OH)2 (s) + aqua —> Mg2+ (aq) + 2OH- (aq)

Question 7

Metal oxide to form an Alkali

Answer 7

CaO (s) + H2O (l) —> Ca2+ (aq) + 2OH- (aq)

Question 8

Ammonia to form an Alkali

Answer 8

NH3 (g) + H2O (l) —> NH4+(aq) + OH- (aq)

Question 9

Salt

Answer 9

The ionic compound formed when the H+ ions in an acid is replaced by positive metal ions or ammonium ions.

Question 10

Charges of Gr 1, Gr 2 and Gr 3

Answer 10

Gr 1 = 1+
Gr 2 = 2+
Gr 3 = 3+

Question 11

Charges of Gr 6, Gr 7 and Gr 8

Answer 11

Gr 6 = 2-
Gr 7 = 1-
Gr 8 = 0

Question 12

Charges of Ag, Zn and NH4

Answer 12

Ag = 1+
Zn = 2+
NH4 = 1+

Question 13

Charges of CO3, SO4, NO3, PO4, HCO3, OH

Answer 13

CO3 = 2-
SO4 = 2-
NO3 = 1-
PO4 = 3-
HCO3 = 1-
OH = 1-

Question 14

Acid + Metal hydroxide

Answer 14

Acid + Metal hydroxide —> Salt + Water

Question 15

Acid + Metal carbonate

Answer 15

Acid + Metal carbonate —> Salt + Water + Carbon dioxide

Question 16

Acid + Metal oxide

Answer 16

Acid + Metal oxide —> Salt + Water

Question 17

Acid + Metal

Answer 17

Acid + Metal —> Salt + Hydrogen

Question 18

Acid + Ammonia

Answer 18

Acid + Ammonia —> Ammonium Salt

Question 19

Soluble ions

Answer 19

Gr. 1 ions
Ammonium ions
Nitrate ions
Hydrogen carbonate ions
Halides, except with Ag, Pb, and Hg
Sulfates, except with Ag, Pb, Ca, Sr and Br

Question 20

Insoluble ions

Answer 20

Oxide ions, except with Ca and Ba
Carbonate ions, except with Gr. 1, Ammonium ions
Phosphate ions, except with Gr. 1, Ammonium ions, Ca, Mg, Sr and Ba
Hydroxide ions, except with Gr. 1, Ammonium ions
Sulfide ions, except with Gr. 1, Ammonium ions
Dichromate, except with Gr. 1, Ammonium ions, Ca and Mg

Question 21

d.p in mean titre

Answer 21

2 d.p

Question 22

How close should result be in a mean

Answer 22

0.10 cm3

Question 23

Identifying Halides

Answer 23

1. Add silver nitrate solution and dilute nitric acid to the unknown solution and record observations
2. Add dilute NH3 to unknown Ag halide and record observations
3. Add concentrated NH3 to unknown Ag halide and record observations

Cl = white ppt, dissolves in dilute, dissolves in conc
Br = cream ppt, insoluble in dilute, dissolves in conc
I = yellow ppt, insoluble in dilute, insoluble in conc

Question 24

Identifying sulphates

Answer 24

1. Add barium nitrate

2. White precipitate should form

Question 25

Carbonate ions

Answer 25

1. Add dilute nitric acid to the unknown
2. If carbonate ions are present, there should be effervesce
3. Limewater should turn cloudy indicating CO2

Question 26

test for Ammonium ions

Answer 26

1. Add sodium hydroxide to the unknown
2. Warm/ heat gently
3. Test for ammonia gas (release of OH- ions) using damp red litmus paper which should turn blue

Question 27

Order of Anion tests

Answer 27

1. Carbonate test, sulfate + halide don’t give off gas
2. Sulfate test, chloride gives of white ppt
3. Halide test, the previous tests with rule. them out.