Qualitative Analysis

Question 1

Name a benefit of using chlorine in water treatment

Answer 1

Kills bacteria

Question 2

What type of ions do halogens form?

Answer 2

1- halides

Question 3

What is the outer shell electron configuration of the halogens?

Answer 3

s2 p5

Question 4

What are the colours of Cl2, Br2 and I2 solutions in organic solvents?

Answer 4

Pale green, orange, violet

Question 5

How does the pH of a group 2 hydroxide solution change down the group?

Answer 5

Increases - more alkaline

Question 6

What is formed from barium reacting with nitric acid?

Answer 6

Barium nitrate - Na(NO3)2

Question 7

What is formed from magnesium reacting with oxygen?

Answer 7

Magnesium Oxide (MgO)

Question 8

What is formed from strontium reacting with water?

Answer 8

Strontium hydroxide - Sr(OH)2

Question 9

Define disproportionation

Answer 9

When an element is both reduced and oxidised at the same time

Question 10

What is the correct sequence of tests for halides, carbonates and sulphates?

Answer 10

Carbonate test with acid then sulfate test with barium ions then halide tests.

Question 11

Identify the test for halide ions and colours of precipitates

Answer 11

Add silver nitrate; Cl is white, Br is cream, I is yellow

Question 12

What is the trend in reactivity down group 2?

Answer 12

Increases down the group

Question 13

What is the outer shell electron configuration of Group 2 metals?

Answer 13

s2

Question 14

What are the products when chlorine reacts with water?

Answer 14

HClO and HCl

Question 15

When group 2 oxides react with water what type of compound forms?

Answer 15

The hydroxide eg calcium hydroxide

Question 16

What are the products when chlorine reacts with dilute, cold NaOH?

Answer 16

NaClO, NaCl and H2O

Question 17

Name the test and positive result for sulfate ions

Answer 17

Add aqueous barium chloride see white precipitate

Question 18

What is formed from calcium reacting with water?

Answer 18

Calcium hydroxide

Question 19

What is NaClO?

Answer 19

Sodium chlorate(I) is bleach

Question 20

Name a use of calcium hydroxide

Answer 20

Neutralising acidic soil

Question 21

Name the test and positive result for carbonate ions

Answer 21

React with dilute nitric acid; effervescence - could check with lime water turning cloudy

Question 22

Describe and explain the trend in BP from Cl to Br to I

Answer 22

Increases due to more electrons so stronger London forces

Question 23

Explain why halogens are oxidising agents

Answer 23

They gain electrons (are reduced) taking electrons from other species

Question 24

What is formed from barium reacting with oxygen?

Answer 24

Barium oxide

Question 25

Explain why group 2 metals are reducing agents

Answer 25

The elements lose electrons (are oxidised) giving these to another species

Question 26

Describe the effect of adding dilute and conc ammonia to silver halide precipitates

Answer 26

AgCl soluble in dilute NH3, AgBr soluble only in conc NH3, AgI not soluble even in conc NH3

Question 27

Name two risks of using chlorine in water treatment

Answer 27

Chlorine is toxic; can react with organic compounds in water to make carcinogenic chloroalkanes

Question 28

What ions do group 2 elements form?

Answer 28

2+

Question 29

Why are magnesium hydroxide and calcium carbonate used in antacids?

Answer 29

They neutralise stomach acid

Question 30

Which of the other halogens can bromine displace?

Answer 30

Just iodine

Question 31

What is the molecular form of all halogens?

Answer 31

Diatomic molecules

Question 32

What is formed form magnesium reacting with hydrochloric acid?

Answer 32

Magnesium chloride

Question 33

What are the colours of Cl2, Br2 and I2 solutions in water?

Answer 33

Pale green, orange, brown

Question 34

What is the trend in reactivity down the halogens?

Answer 34

Decreases

Question 35

Identify the test and positive results for ammonium ions

Answer 35

Add NaOH, warm and test gas/fumes with moist indicator paper. Will turn paper blue (alkaline)