Group 7 - The Halogens

Question 1

What colour is F2 at room temperature?

Answer 1

Pale yellow

Question 2

What is the physical state of F2 at room temperature?

Answer 2

Gas

Question 3

What colour is Cl2 at room temperature?

Answer 3

Green

Question 4

What is the physical state of chlorine at room temperature?

Answer 4

Gas

Question 5

What colour is Br2 at room temperature?

Answer 5

Red-brown

Question 6

What is the physical state of Br2 at room temperature?

Answer 6

Liquid

Question 7

What colour is I2 at room temperature?

Answer 7

Grey

Question 8

What is the physical state of I2 at room temperature?

Answer 8

Solid

Question 9

What is the trend in boiling points of halogens down a group?

Answer 9

Increases

Question 10

Why does the boiling point increase down a group?

Answer 10

Due to the increased strength of the Van der Waals as the relative mass of molecules increases

Question 11

What is the trend in electronegativity down a group of halogens?

Answer 11

Decreases

Question 12

Why does electronegativity increase down the group?

Answer 12

The halogens are highly electronegative
Larger atoms attract less than smaller ones
Their outer electrons are further from the nucleus and more shielded

Question 13

Are halogens oxidising or reducing agents? Why?

Answer 13

Oxidising agents

They gain an electron

Question 14

What happens to the oxidising power of the halogens as you move down the group?

Answer 14

They become less oxidising

Question 15

What does “halide” describe?

Answer 15

The negative X- ion

Question 16

What does the term “Halogen” refer to?

Answer 16

The atom X or the molecule X2

Question 17

What colour is potassium chloride solution? (KCl)

Answer 17

Colourless

Question 18

What is the reaction between potassium chloride solution and chlorine water?

Answer 18

No reaction

Question 19

What colour is chlorine water (Cl2)?

Answer 19

Colourless

Question 20

What colour is potassium bromide solution (KBr)?

Answer 20

Colourless

Question 21

What is the reaction between potassium bromide solution and chlorine water?

Answer 21

Orange solution (Br2) formed

Question 22

What colour is potassium iodide solution (KI)?

Answer 22

Colourless

Question 23

What is the reaction between potassium iodide solution and chlorine water?

Answer 23

Brown solution (I2) formed

Question 24

What is the colour of bromine water (Br2)?

Answer 24

Orange

Question 25

What is the reaction between potassium chloride solution and bromine water?

Answer 25

No reaction

Question 26

What is the reaction between potassium bromide solution and bromine water?

Answer 26

No reaction

Question 27

What is the reaction of potassium iodide solution and bromine water?

Answer 27

Brown solution (I2) formed

Question 28

What colour is iodide solution (I2)?

Answer 28

Brown

Question 29

What is the reaction between the potassium chloride solution and iodine solution?

Answer 29

No reaction

Question 30

What is the reaction between potassium bromide solution and iodide solution?

Answer 30

No reaction

Question 31

What is the reaction between potassium iodide solution and iodine solution?

Answer 31

No reaction

Question 32

What is the equation for the displacement reaction of chlorine and potassium iodide ions?

Answer 32

Cl2 + 2KI -> 2KCl +I2

Question 33

What is the ionic equation for the displacement reaction of chlorine and potassium iodide ions?

Answer 33

Cl2 + 2I- -> 2Cl- + I2

Question 34

What is the equation for the displacement reaction between chlorine and potassium bromide?

Answer 34

Cl2 + 2KBr -> 2KCl + Br2

Question 35

What is the ionic equation for the displacement reaction between chlorine and potassium bromide?

Answer 35

Cl2 + 2Br- -> 2Cl- + Br2

Question 36

What is the equation for the displacement reaction between bromine and potassium iodide?

Answer 36

Br2 + 2KI -> 2KBr + I2

Question 37

What is the ionic equation for the displacement reaction between bromine and potassium iodide?

Answer 37

Br2 + 2I- -> 2Br- + I2

Question 38

Why won't iodine displace either Cl- or Br- halide?

Answer 38

It is below chlorine and bromine in group 7 so it is less reactive

Question 39

What is formed when you mix chlorine gas with cold, dilute sodium hydroxide solution at room temperature?

Answer 39

``` Sodium chlorate (I) solution NaClO ```

Question 40

What is a use of NaClO?

Answer 40

Household bleach

Question 41

What is disproportionation?

Answer 41

In the reaction, chlorine being both oxidised and reduced

Question 42

What is the equation for the formation of bleach?

Answer 42

2NaOH +Cl2 -> NaClO + NaCl + H2O

Question 43

What is chlorine's oxidation state in Cl2?

Answer 43

O

Question 44

What is chlorine's oxidation state in NaClO?

Answer 44

+1

Question 45

What is chlorine's oxidation state in NaCl?

Answer 45

-1

Question 46

What happens when chlorine reacts with water?

Answer 46

Disproportionation

Question 47

What is formed when chlorine reacts with water?

Answer 47

A mixture of chloride ions and chlorate (I) ions

Question 48

What is the equation when chlorine reacts with water?

Answer 48

Cl2 + H2O 2H+ + Cl- + ClO-

Question 49

What is chlorine's oxidation state in Cl-?

Answer 49

-1

Question 50

What is chlorine's oxidation state in ClO-?

Answer 50

+1

Question 51

Why is chlorine used in water treatment?

Answer 51

Chlorate ions kill bacteria

Question 52

Why is chlorine an important part of water treatment?

Answer 52

It kills disease-causing microorganisms Prevents reinfection further down the supply Prevents the growth of algae, eliminating bad tastes and smells and removing discolouration caused by organic compounds

Question 53

What are the risks of using chlorine in water treatment?

Answer 53

Chlorine is toxic Harmful if chlorine gas is breathed in - irritates the respiratory system Liquid chlorine causes chemical burns on the skin and eyes