Group 7 And Redox

Question 1

Property of flourine, chlorine, bromine and iodine

Answer 1

1.Pale yellow gas
2. Pale green gas
3. Brown - orange liquid
4. Grey solid ( purple gas on heating)

Question 2

boiling points down group 7

Answer 2

• increases
• van der waal forces increases
• bc increased size and relative mass of atoms

Question 3

What are the changes in physical state down group 7

Answer 3

• gas at top
  -solid at bottom

Question 4

Trend in electronegativity

Answer 4

• decreases
• atoms get larger
  -Distance between positive and bonding electrons increases
• more shielding

Question 5

How to displacement in group 7 work

Answer 5

more reactive halogens will deisplace less reactive halide ions

Halogen Displaces halide is halide is lower in periodic table

Question 6

Trend in reactivity

Answer 6

• decreases
• atoms with smaller radius attract electrons better than larger ions

Question 7

What happens to oxidation down group

Answer 7

it is less oxidising

Question 8

Reaction between cl2 and br2

Answer 8

orange solution (Br2) made
Chlorine more reactive than bromide ion

Cl2 + 2Br- — 2cl- + Br2

Question 9

Reaction between Iodide and Cl2

Answer 9

Forms brown solution (I2) made

Cl2 + 2I- — 2Cl- + I2

Question 10

reaction between Br2 and iodide

Answer 10

Brown solution formed (I2) made

Br2 + 2I- —> 2Br- + I2

Question 11

How to form bleach

Answer 11

2NaOH +Cl2 —> NaClO + NaCl + H2O

Question 12

What happens to chlorine in disproportionation reaction

Answer 12

Chlorine has simultaneosuly been reduced and oxidised

Question 13

Reaction with water and chlorine

Answer 13

H2O + cl —> 2H+ + Cl- + ClO-

This is a siproportionation reaction

Question 14

Sunlight decomposing chlorine

Answer 14

2H2O + Cl2 —> 4H+ + 2Cl- + O2

Cant clean bacteria so cleaned regulary in pools

Question 15

Ionic radius trend in halides

Answer 15

• increases
• distance between nucleus and outer electrons is larger
• more shielding
• FOA is weaker

Question 16

Why is I- a more powerful reducing agent than F-

Answer 16

the outer electron is lost more readily

Question 17

Explain why halide ions loses electrons down the grouo

Answer 17

Because it becomes easier to lose an elxtron because ions are larger and more sheilding

Question 18

State the colour of the solution when adding silver nitrate to halides

Answer 18

F- = no ppt
Cl- = white
Br- = cream
I = pale yellow

Question 19

State reactions with ammonia with halides

Answer 19

Agcl dissolves in DILUTE
AgBr dissolved in CONC
AgI will NOT DISSOLVe

Question 20

Why do we had nitric acid firsy

Answer 20

to remove carbonates and get a false positive

Question 21

How to do flame test for ions

Answer 21

1. Dip nicrhome wire in conc HCl
2. Dip into sample
3. Place oop into blue bunsen flame

Dark REd = ca
Red = sr
Green = ba

Question 22

How to test for ammonium compounds

Answer 22

• add NaOH and gently heat
  . Ammonia has will be produced
• use damp red limus paper and ammonia will dissolve in water
• turn blue

Question 23

Testing for hydroxides

Answer 23

• alkaline so turn red litmus paper blue

Question 24

Testing for carbontates

Answer 24

• HCl reacts with carbonates to make carbon dioxide gas
• bubbled through lime waer it turns cloudy

Question 25

Test for sulfates

Answer 25

- add HCl removing carbinates - add Barium chloride - white ppt - insoluble

Question 26

order for testing ions

Answer 26

1. Carbonates 2. Test for sulfates if no carbonates 3. Test for halides if no sulfates