Group 7

Question 1

What are the 6 reactions that halogens undergo called?

Answer 1

1) displacement reactions
2) disproportionation reaction of chlorine
3) test for halide ions
4) hydrogen halides with water and ammonia (formation of acids)
5) solid halide slats with concentrated sulfuric acid
6) Reaction with hydrogen

Question 2

What do the halogens do in the displacement reaction

Answer 2

-the halogen displaces the less reactive halide ions from solution

Question 3

What is the general equation for displacement of halogens

Answer 3

• General Equation:
  X2 + YZ —> XZ + Y

Question 4

What observation can you make from a displacement reaction with chlorine and bromine

Answer 4

-orange/brown solution (Br2)

Question 5

What would be the equation for a displacement reaction with Cl and Br

Answer 5

• Cl2 (aq) + NaBr (aq) —> 2NaCl (aq) + Br2 (aq)

Question 6

What reagents are used in the displacement reaction of halogens

Answer 6

-solution of a halide ion
-an aqueous solution of a more reactive halogen

Question 7

What observation can you make from a displacement reaction with chlorine and iodine

Answer 7

-brown solution (I2) forms

Question 8

What would be the equation for a displacement reaction with Cl and I

Answer 8

-brown solution (I2) forms

Question 10

What halogen in is commonly talked about when it comes to disproportionation

Answer 10

• chlorine

Question 11

Write the equation for the disproportionation of Cl with H2O

Answer 11

Cl2 + H2O —> HCl +HClO

Question 12

What is the equation for Cl being reduced and oxidised in disproportionation reactions

Answer 12

reduced: Cl2 —> HCl (0 -> -1)
oxidised: Cl2 —> HClO (0 -> +1)

Question 13

What are the reagents, conditions and observations made when chlorine is disproportionated with water

Answer 13

Reagents: chlorine gas and water
Conditions: rooms temp
Observations: pale green chlorine solution forms

Question 14

What is the use of the product made from the disproportionation of Cl with H2O

Answer 14

• HClO (caloric acid) acts as a disinfectant in water treatment

Question 15

Write the equation for the disproportionation of Cl with NaOH (formation of bleach)

Answer 15

Cl2 + 2NaOH —> NaCl + NaClO + H2O

Question 16

What are the reagents and conditions used in disproportionation of chlorine with aqueous sodium hydroxide

Answer 16

Reagents: chlorine gas and cold dilute NaOH
Conditions: room temp

Question 17

What is the use of NaClO from the disproportionation of chlorine with aqueous sodium hydroxide

Answer 17

-bleach

Question 18

Write the equation for the disproportionation of Cl with hot, excess NaOH

Answer 18

3CL2 + 6NaOH —> 5NaCl + NaClO3 + 3H2O

Question 19

What are the reagents and conditions used in disproportionation of chlorine with hot, excess sodium hydroxide

Answer 19

Reagents: chlorine and hot concentrated NaOH
Conditions: Heated

Question 20

What is the use of NaClO (V) from the disproportionation of chlorine with hot, excess sodium hydroxide

Answer 20

• produces sodium chlorate (V), which is sued in weedkillers

Question 21

What is the general formula the test for halide ions

Answer 21

Ag+ (aq) + X- (aq) —> AgX (s)

Question 22

What are the reagents used for the test for halide ions

Answer 22

-nitric acid
-silver nitrate

Question 23

Why is nitric added in the test for ions reaction

Answer 23

-to remove any impurities

Question 24

Why do we test the silver halides with ammonia after testing them with silver nitrate

Answer 24

• to confirm the identity of the halide ion because the colours of the precipitate may look similar

Question 25

What is the observation when testing for halide ions when a chloride ion is present

Answer 25

-white precipitate

Question 26

What is the observation when testing for halide ions when a bromide ion is present

Answer 26

-cream precipitate

Question 27

What is the observation when testing for halide ions when a iodine ion is present

Answer 27

-yellow precipitate

Question 28

What happens to AgCl when dissolved in dilute NH3

Answer 28

-It dissolves

Question 29

What happens to AgBr when dissolved in dilute NH3

Answer 29

-insoluble (doesn’t dissolve)

Question 30

What happens to AgI when dissolved in dilute NH3

Answer 30

-Insoluble (doesn’t dissolve)

Question 31

What happens to AgCl when dissolved in concentrated NH3

Answer 31

-it dissolves

Question 32

What happens to AgBr when dissolved in concentrated NH3

Answer 32

-dissolves

Question 33

What happens to AgI when dissolved in concentrated NH3

Answer 33

-insoluble (it doesn’t dissolve)

Question 34

Why does AgCl dissolve in both dilute and concentrated NH3

Answer 34

-because it forms this complex easily

Question 35

Why does AgBr dissolve in only concentrated NH3

Answer 35

-because it is less soluble and so doesn’t form the complex easily

Question 36

Why does AgI not dissolve in either dilute or concentrated NH3

Answer 36

-because it is too insoluble and doesn’t form complex ions

Question 37

What is the general formula for the reaction of hydrogen halides with water (formation of acids)

Answer 37

X- (aq) + H2O (l) ⇌ HX (aq) + OH- (aq)

Question 38

What is the general formula for the reaction of hydrogen halides with ammonia

Answer 38

X- (aq) + NH3 (aq) ⇌ NH4X (aq)

Question 39

What are the observations when reacting hydrogen halides with water

Answer 39

-forms strong acids (except HF which is weak) - pH <1 in solution

Question 40

What are the observations when reacting hydrogen halides with ammonia

Answer 40

-white fumes of ammonium halide form

Question 41

Write the general equation for the reaction of solid halide salts with concentrated sulfuric acid

Answer 41

NaX + H2SO4 —> HX + NaHSO4

Question 42

What observation can you make when reacting NaCl with concentrated H2SO4

Answer 42

-misty white fumes (HCl)

Question 43

What observation can you make when reacting NaBr with concentrated H2SO4

Answer 43

-misty white fumes (HBr)

Question 44

What observation can you make when reacting NaI with concentrated H2SO4

Answer 44

-misty white fumes (HI)

Question 45

What type of reaction is the reaction of NaCl and H2SO4

Answer 45

-acid- base only reaction

Question 46

What type of reaction is the reaction of NaBr and H2SO4

Answer 46

-redox reaction

Question 47

What type of reaction is the reaction of NaI and H2SO4

Answer 47

-strong redox reaction

Question 48

What is the general formula for the reaction of halogens with hydrogen

Answer 48

X2 + H2 —> 2HX