Question 1

Describe the physical appearance of bromine at room temperature

Accepted Answer

red brown liquid

Answer

pale yellow gas

Answer

black solid

Answer

pale green gas

Question 2

Describe the physical appearance of iodine at room temperature

Accepted Answer

black solid

Answer

red brown liquid

Answer

pale yellow gas

Answer

green gas

Question 3

Describe the physical appearance of chlorine at room temperature

Accepted Answer

green gas

Answer

pale yellow gas

Answer

black solid

Answer

red brown liquid

Question 4

Describe the physical appearance of bromine at room temperature

Accepted Answer

red brown liquid

Answer

pale yellow gas

Answer

pale green gas

Answer

black solid

Question 5

Describe and explain the trend in boiling point of the halogens

Accepted Answer

The boiling point increases down the group because halogens have a: larger Mr , larger surface area. Therefore there are stronger van der Waals interactions between molecules which requires more energy to overcome

Answer

The boiling point increases down the group because halogens have a: larger Mr , larger surface area. Therefore there are weaker van der Waals interactions between molecules which requires more energy to overcome

Question 6

Describe and explain the trend in reducing ability of the halides

Accepted Answer

Reducing ability increases down the group, more shielding, larger atomic radius, weaker attraction between the nucleus and outer electrons, easier to lose electrons

Answer

Reducing ability increases down the group, more shielding, larger atomic radius, stronger attraction between the nucleus and outer electrons, easier to lose electrons

Answer

Oxidising ability decreases down the group, more shielding, larger atomic radius, weaker attraction between the nucleus and an incoming electron

Answer

Oxidising ability decreases down the group, more shielding, larger atomic radius, stronger attraction between the nucleus and an incoming electron

Question 7

Describe and explain the trend in oxidising ability of the halogens

Accepted Answer

Oxidising ability decreases down the group, more shielding, larger atomic radius, weaker attraction between the nucleus and an incoming electron

Answer

Reducing ability increases down the group, more shielding, larger atomic radius, weaker attraction between the nucleus and outer electrons, easier to lose electrons

Answer

Reducing ability increases down the group, more shielding, larger atomic radius, stronger attraction between the nucleus and outer electrons, easier to lose electrons

Answer

Oxidising ability decreases down the group, more shielding, larger atomic radius, stronger attraction between the nucleus and an incoming electron

Question 8

Describe and explain the trend in electronegativity of the halogens

Accepted Answer

General decrease down the group due to: increased shielding, larger atomic radius, therefore weaker attraction between nucleus and 2 electrons in covalent bond, these factors outweigh the increased nuclear charge

Answer

General decrease down the group due to: increased shielding, larger atomic radius, therefore weaker attraction between nucleus and 2 electrons in covalent bond, these factors add to the increased nuclear charge

Question 9

Which halogen species is the best oxidising agent?

Accepted Answer

F2

Answer

I2

Answer

Br2

Answer

Cl2

Question 10

Define: displacement reaction

Accepted Answer

A reaction in which an element is displaced out of a compound by a more reactive element

Answer

A reaction in which an element is displaced out of a compound by a less reactive element

Question 11

Explain why chlorine displaces iodine ions from solution

Accepted Answer

Chlorine is a stronger oxidising agent than iodine, therefore iodide ions lose their electrons to chlorine, producing iodine.

Answer

Chlorine is a weaker oxidising agent than iodine, therefore iodide ions gain their electrons to chlorine, producing iodine.

Question 12

Aqueous chlorine liberates bromine from a solution of potassium bromide. Explain why this is a redox reaction.

Accepted Answer

Chlorine’s oxidation state decreases from 0 --> -1 and bromide’s oxidation state increases from -1 --> 0.

Answer

Chlorine’s oxidation state increases from -1 --> 0 and bromide’s oxidation state decreases from 0 --> -1.

Question 13

Write the ionic equation and observation for the reaction between chlorine and potassium bromide

Accepted Answer

Ionic equation: Cl₂ + 2Br^–→ Br₂ + 2Cl^–

Observation: yellow/ orange solution

Answer

Ionic equation: Cl₂ + 2Br^–→ Br₂ + 2Cl^–

Observation: brown solution

Question 14

Write the ionic equation and observation for the reaction between chlorine and potassium iodide

Accepted Answer

Ionic equation: Cl₂ + 2I^–→ I₂ + 2Cl^–

Observation: brown solution

Answer

Ionic equation: Cl₂ + 2I^–→ I₂ + 2Cl^–

Observation: orange solution

Question 15

Write the ionic equation and observation for the reaction between bromine and potassium iodide

Accepted Answer

Ionic equation: Br₂ + 2I^–→ I₂ + 2Br^–

Observation: brown solution

Answer

Ionic equation: Br₂ + 2I^–→ I₂ + 2Br^–

Observation: orange solution

Question 16

What reagent is used to test for aqueous halide ions?

Accepted Answer

Acidified silver nitrate

Answer

Acidified barium chloride

Question 17

Describe the test for halide ions in aqueous solution

Accepted Answer

Add dilute nitric acid, Add silver nitrate solution, Add dilute ammonia, Add concentrated ammonia

Answer

Add dilute nitric acid, Add silver nitrate solution, Add concentrated ammonia, Add dilute ammonia

Question 18

Why do you add dilute nitric acid before the silver nitrate?

Accepted Answer

To remove any other anions such as OH^- or CO₃^2-

Answer

To remove any other cations such as OH^- or CO₃^2-

Question 19

Which colour precipitate does AgI form?

Accepted Answer

yellow ppt

Answer

cream ppt

Answer

white ppt

Question 20

Which colour precipitate does AgCl form?

Accepted Answer

white ppt

Answer

yellow ppt

Answer

cream ppt

Question 21

Which colour precipitate does AgBr form?

Accepted Answer

cream ppt

Answer

white ppt

Answer

yellow ppt

Question 22

How do you confirm whether you have AgCl, AgBr or AgI?

Accepted Answer

Add dilute ammonia, if it dissolves to form a colourless solution it was AgCl, if it doesn't, add concentrated ammonia, if it dissolves to form a colourless solution you had AgBr, if it doesn't you had AgI

Answer

Add concentrated ammonia, if it dissolves to form a colourless solution it was AgCl, if it doesn't, add dilute ammonia, if it dissolves to form a colourless solution you had AgBr, if it doesn't you had AgI

Question 23

On addition of dilute nitric acid, what are possible ionic equations if other anions are present?

Accepted Answer

H⁺_(aq)+ OH^-₍_aq)→ H₂O_(l)

2H⁺_(aq)+ CO₃^2-₍_aq)→ H₂O_(l)+ CO_2(g)

Answer

H⁺_(aq)+ OH^-₍_aq)→ H₂O_(l)

H⁺_(aq)+ CO₃^2-₍_aq)→ H₂O_(l)+ CO_2(g)

Question 24

metal + water -->

Accepted Answer

metal hydroxide + hydrogen

Answer

salt + water + carbon dioxide

Question 25

metal carbonate + acid -->

Accepted Answer

salt + water + carbon dioxide

Answer

salt + water

Question 26

metal oxide + acid -->

Accepted Answer

salt + water

Answer

salt + water + carbon dioxide

Question 27

metal hydroxide + acid -->

Accepted Answer

salt + water

Answer

salt + water + carbon dioxide

Question 28

metal oxide + water -->

Accepted Answer

metal hydroxide

Answer

salt + water + carbon dioxide

Question 29

Which silver halide does not react with ammonia?

Accepted Answer

AgI

Answer

AgF

Answer

AgCl

Question 30

Ionic equation for addition of concentrated ammonia with AgBr:

Accepted Answer

AgBr_(s)+ 2NH_3(aq) -->[Ag(NH₃)₂]⁺_(aq)+ Br^-_(aq)

Answer

AgBr_(s)+ 2NH_3(aq)--> [Ag(NH₃)₃]⁺_(aq)+ Br^-_(aq)

Question 31

Ionic equation for addition of dilute ammonia with AgCl:

Accepted Answer

AgCl_(s)+ 2NH_{3(aq) -->}[Ag(NH₃)₂]⁺_(aq)+ Cl^-_(aq)

Answer

AgCl_(s)+ 2NH_{3(aq) -->}[Ag(NH₃)₃]⁺_(aq)+ Cl^-_(aq)

Question 32

Which halogen species is the strongest reducing agent?

Accepted Answer

I-

Answer

F-

Question 33

What reagent is used to test for solid halide salts?

Accepted Answer

Concentrated H₂SO₄

Answer

Concentrated HNO₃

Question 34

Write the general balanced equation for the reaction that takes place between all sodium halide salts and conc H₂SO_4.State your observation

Accepted Answer

NaX_(s) + H₂SO_4(aq) → NaHSO_4(s) + HX_(g)

Observation: misty white fumes (HX_(g))

Answer

NaX_(s) + H₂SO_4(aq) → NaHSO_4(l) + HX_(g)

Observation: misty white fumes (HX_(g))

Question 35

NaX_(s) + H₂SO_4(aq) → NaHSO_4(s) + HX_(g)what type of reaction is it?

Accepted Answer

acid-base halide ion = base

Answer

redox halide ion = reduced

Question 36

Which halide ions are strong enough reducing agents to reduce H₂SO₄?

Accepted Answer

Br- and I-

Answer

F- and Cl-

Question 37

What is the oxidation state of sulfur in SO₂?

Accepted Answer

+4

Answer

+6

Question 38

What is the oxidation state of sulfur in H₂SO₄?

Accepted Answer

+6

Answer

+4

Question 39

What species can bromide ions reduce H₂SO₄to?

Accepted Answer

SO2

Answer

S

Question 40

What species can iodide ions reduce H₂SO₄to?

Accepted Answer

SO₂, S, H₂S

Answer

SO₂, SO, H₂S

Question 41

oxidation state of S in H₂S

Accepted Answer

-2

Answer

0

Question 42

oxidation state of S in S

Accepted Answer

0

Answer

-2

Question 43

Write a general oxidation half equation for a halide ion

Accepted Answer

2 X^–→ X₂ + 2 e^–

Answer

2 X^–+2e^-→ X₂

Question 44

Which is not the ionic equation for the redox reaction that occurs when sodium iodide reacts with concentrated H₂SO_4.

Accepted Answer

2H⁺_(aq)+ 2Br^-_(aq)+H₂SO_{4 (aq)} → SO_2(g) + 2H₂O_(l) + Br_{2 (l)}

Observations: brown/ orange gas produced (Br₂)

Answer

2H⁺_(aq) + 2I^-_(aq)+H₂SO_{4 (aq)} → SO_2(g) + 2H₂O_(l) + I_{2 (s)}

Observations: black solid/ purple gas (I₂)

Answer

H₂SO_4(aq) + 8H⁺_(aq) + 8I^–_(aq)→ H₂S_(g) + 4 H₂O_(l) + 4I_{2 (s)}

Observations: bad egg smell (H₂S), black solid/ purple gas (I₂)

Answer

H₂SO_4(aq)+ 6H⁺_(aq)+ 6I^–_(aq)→ S_(s) + 4 H₂O_(l) + 3I_{2 (s)}

Observations: yellow solid (S), black solid/ purple gas (I₂)

Question 45

Write the ionic equation for the redox reaction that occurs when sodium bromide reacts with concentrated H₂SO_4.State your observations

Accepted Answer

2H⁺_(aq)+ 2Br^-_(aq)+H₂SO_{4 (aq)} → SO_2(g) + 2H₂O_(l) + Br_{2 (l)}

Observations: brown/ orange gas produced (Br₂)

Answer

H₂SO_4(aq)+ 6H⁺_(aq)+ 6I^–_(aq)→ S_(s) + 4 H₂O_(l) + 3I_{2 (s)}

Observations: yellow solid (S), black solid/ purple gas (I₂)

Answer

2H⁺_(aq)+ 2Br^-_(aq)+H₂SO_{4 (aq)} → SO_2(g) + 2H₂O_(l) + Br_{2 (l)}

Observations: black gas produced (Br₂)

Answer

2H⁺_(aq) + 2I^-_(aq)+H₂SO_{4 (aq)} → SO_2(g) + 2H₂O_(l) + I_{2 (s)}

Observations: black solid/ purple gas (I₂)

Question 46

steps in writing half equations

Accepted Answer

identify oxidation state, ensure element changing oxidation state is balanced, add electrons (OILRIG, O=right side, R=left side) balance O with addition of water, balance H with addition of H+

Answer

identify oxidation state, ensure element changing oxidation state is balanced, add electrons (OILRIG, O=left side, R=right side) balance O with addition of water, balance H with addition of H+

Question 47

Describe the tests for halide ions in solid salts

Accepted Answer

1) Place a small spatula of solid potassium halide in a test tube

2) Add 5 drops of concentrated sulfuric acid

Observation for all halides: effervescence, misty white fumes (HX_(g))

General overall equation: NaX_(s) + H₂SO_4(l) → NaHSO_4(s) + HX_(g)

Answer

1) Place a small spatula of solid potassium halide in a test tube

2) Add 5 drops of concentrated sulfuric acid

Observation for all halides: effervescence, misty white fumes (HX_(g))

General overall equation: NaX_(s) + H₂SO_4(l) → NaHSO_4(l) + HX_(g)

Question 48

If halide = Cl-

Accepted Answer

Test the gas evolved with damp blue litmus paper

Observation: Turns red

Answer

Observations: effervescence, misty white fumes, orange/brown gas produced (Br₂) Test the gas evolved using a strip of filter paper that has been dipped in acidified potassium dichromate solution

Observation: turns from orange --> green (Cr+6 -->+3 by oxidising SO₂)

Answer

Observations: effervescence, misty white fumes, purple gas produced, black solid (I₂), bad egg smell (H₂S), yellow solid (S)

Test the gas evolved using a strip of filter paper that has been dipped in lead nitrate solution Observation: Turns black (PbS)

Question 49

State 2 uses of chlorine

Accepted Answer

To treat swimming pools and drinking water

Answer

To treat swimming pools and waste water

Question 50

Define: disproportionation reaction

Accepted Answer

A reaction in which the same element is both oxidised and reduced

Answer

A reaction in which a different element is oxidised and another is reduced

Question 51

Write the equation for the reaction that takes place when chlorine is added to water in the presence of sunlight

Accepted Answer

2Cl_2(g) + 2H₂O_(l)--> 4HCl_(aq) + O_{2 (g)}

Answer

Cl₂ + H₂O ⇌ HCl + HClO

Question 52

Write the equation for the reaction that takes place when chlorine is added to cold water

Accepted Answer

Cl₂ + H₂O ⇌ HCl + HClO

Answer

2Cl_2(g) + 2H₂O_(l)--> 4HCl_(aq) + O_{2 (g)}

Question 53

How does chlorine sterilise water?

Accepted Answer

HClO kills bacteria as the HClO is used up, the equilibrium shifts to the right, producing more HClO

Answer

HClO kills bacteria as the HClO is used up, the equilibrium shifts to the left, producing more HClO

Question 54

Explain why chlorine is added to water even though it is toxic

Accepted Answer

Reason: it sterilises the water by killing bacteria

Explanation: health benefit outweighs risk as it is only used in small quantities

Answer

Reason: it cleans the water by killing bacteria

Explanation: health benefit outweighs risk as it is only used in small quantities

Question 55

Explain why the pH of pools sterilised with chlorine needs to be slightly alkaline

Accepted Answer

The hydroxide ions react with the acids, this shifts the equilibrium to the right, producing HClO

An acidic solution would favour the backwards reaction, producing more chlorine, which is toxic.

Answer

The hydroxide ions react with the acids, this shifts the equilibrium to the left, producing HClO

An acidic solution would favour the backwards reaction, producing more chlorine, which is toxic.

Question 56

State the disadvantage of the direct chlorination of swimming pools

Accepted Answer

In shallow swimming pools (higher light intensity) chlorine needs to be continuously replaced as the reaction above goes to completion

Answer

In shallow swimming pools (lower light intensity) chlorine needs to be continuously replaced as the reaction above goes to completion

Question 57

What can be used as an alternative to chlorine?

Accepted Answer

NaClO: Sodium chlorate (I)

Answer

NaClO: Sodium chlorate (II)

Question 58

Write an equation to show what happens when sodium chlorate (I) dissolves in water

Accepted Answer

NaClO_(s)+ H₂O_(l)⇌ NaOH_(aq) + HClO_(aq)

Answer

NaClO_(s)+ H₂O_(l)⇌ NaOH_(aq) + HClO_(g)

Question 59

Explain why the pH of pools sterilised with NaClO need to be slightly acidic

NaClO_(s)+ H₂O_(l)⇌ NaOH_(aq) + HClO_(aq)

Accepted Answer

To ensure the equilibrium lies to the right: NaOH will be used up and the equilibrium will shift to the right, producing HClO

Answer

To ensure the equilibrium lies to the left: NaOH will be used up and the equilibrium will shift to the right, producing HClO

Question 60

Give a major use for NaClO and give its IUPAC name

Accepted Answer

The active ingredient in household bleach

sodium chlorate(I)

Answer

The active ingredient in household bleach

sodium chlorate(II)

Question 61

Write an equation for the reaction between chlorine and cold, dilute, aqueous sodium hydroxide. What type of reaction is it?

Accepted Answer

Cl₂ + 2NaOH ⇌ NaClO + NaCl + H₂O

Disproportionation reaction

Answer

Cl₂ + 2NaOH ⇌ NaClO₂ + NaCl + H₂O

Disproportionation reaction

Question 62

Why is it dangerous to acidify an aqueous mixture of sodium chlorate(I) and sodium chloride

Cl₂ + 2NaOH ⇌ NaClO + NaCl + H₂O

Accepted Answer

Protons will react with the hydroxide ions

Shifting the equilibrium to the left

Producing chlorine, which is toxic

Answer

Protons will react with the hydroxide ions

Shifting the equilibrium to the right

Producing chlorine, which is toxic

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