Group 7

Question 1

Group 2 atomic radii down the group?

Answer 1

Increases
Additional electron shells

Question 2

Reactivity down group 7?

Answer 2

Decreases
Need to gain an electron
Atomic radius increases down the group due to additional electron shells
Harder to attract an electron

Question 3

IE down group 7?

Answer 3

Decreases
Greater atomic radius
Increased amounts of shielding
Less energy to remove an electron

Question 4

Boiling point down group 7?

Answer 4

Increases
Simple covalent molecules held with VDWS
VDW forces increase down group
More energy required to overcome forces

Question 5

Oxidising power down group 7?

Answer 5

Decreases
Ability to attract electrons decreases
Shielding increases
Atomic radius increases

Question 6

Cl2 will displace ?

Answer 6

Br- and I- ions due to highest oxidising strength

Question 7

Br2 will displace ?

Answer 7

I- ions due to oxidising strength

Question 8

I2 will displace ??

Answer 8

No halide ions due to lowest oxidising strength

Question 9

Halogens are good ______ agents

Answer 9

oxidising

Question 10

Halides are good _______ agents

Answer 10

reducing

Question 11

Halide ion reducing power down the group?

Answer 11

Increases
Electrons easier to lose from larger ions
Due to increased shielding and ionic radii

Question 12

Sodium fluoride and sulfuric acid reaction

Answer 12

NaF + H2SO4 -> NaHSO4 + HF

Question 13

Sodium chloride and sulphuric acid reaction

Answer 13

NaCl + H2SO4 -> NaHSO4 + HCl

Question 14

Sodium bromide and sulphuric acid reaction

Answer 14

NaBr + H2SO4 -> NaHSO4 + HBr
2HBr + H2SO4 -> Br2 + SO2 + 2H2O

Question 15

Sodium iodide and sulphuric acid reaction

Answer 15

NaI + H2SO4 -> NaHSO4 + HI
2HI + H2SO4 -> I2 + SO2 + 2H2O
6HI + SO2 -> H2S + 3I2 + 2H2O

Question 16

The greater the reducing power, the _______ the reaction and the reason why

Answer 16

Longer

The halide is powerful enough to reduce more species

Question 17

The 3 halide ions reacting with silver nitrate

Answer 17

Cl- has a white AgCl ppt
Br- has a cream AgBr ppt
I- has a yellow AgI ppt

Question 18

The 3 halide ions compounded with Ag reacting with dilute NH3

Answer 18

AgCl ppt’s Cl- ions dissolve, no change in Br- or I- ppts

Question 19

The 3 halide ions compounded with Ag reacting with conc NH3 after dilute NH3

Answer 19

AgBr ppt’s Br- ions dissolve, no change in Cl- (already dissolved) or I- ppts

Question 20

Why use ammonia to distinguish simple test for halide results?

Answer 20

Ppts may be hard to distinguish

Question 21

Chlorine and water to chlorate ions and chloride ions reaction

Answer 21

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

Question 22

Disproportionation reaction

Answer 22

a named element is oxidised and reduced

Question 23

Chlorine and water to oxygen and Hydrochloric acid reaction and conditions

Answer 23

conditions: UV light
It’s needed over the arrow

2Cl2 + 2H2O -> 4HCl + O2

Question 24

What is chlorine used for in water treatment and why do we use it even if it’s toxic?

Answer 24

Killing bacteria
Toxic but benefits of clean, treated water outweigh the risks

Question 25

Bleach production equation and conditions

Answer 25

Conditions: cold, aq NaOH 2NaOH + Cl2 -> NaClO + NaCl + H2O

Question 26

Why acidify AgNO3 before test for halides?

Answer 26

remove other impurities that can form a precipitate

Question 27

Test for sulfates

Answer 27

BaCl2 added, which forms a white ppt of BaSO4

Question 28

Test for hydroxide ions

Answer 28

Alkaline Test with red litmus paper which turns blue Or universal indicator which turns blue/purple

Question 29

Test for carbonates

Answer 29

add HCl fizzing as CO2 is produced gas can be collected and bubbled through limewater limewater turns cloudy

Question 30

What is limewater

Answer 30

calcium hydroxide

Question 31

Test for group 2 ions Ca2+, Sr2+ and Ba2+

Answer 31

Flame tests brick red red pale green in that order

Question 32

Test for ammonium ions and how to speed it up

Answer 32

Basic ammonia gas is given off Hold red litmus over a petri dish of the substance being tested Turns blue if NH4OH is present NaOH can be added to produce the gas faster