Group 7

Question 1

Reducing ability of the Halides

Answer 1

Down the group reducing ability increases as outer electrons are lost more easily

Acid base- react with H2SO4 to form misty fumes

Redox- Br forms SO2 and Br2
I forms SO2, I2, S and H2S

Question 2

Chlorine and water reaction

Answer 2

Chlorine water
Cl2+ H2O <-> HCl + HClO
This is a disproportion reaction as Cl2 is both oxidised and reduced.
turns indicator red then white

In sun
2Cl2 + 2H2O -> 4HCl + O2
Can be used to sterilise water

Question 3

Identification using silver nitrate the ammonia

Answer 3

AgNO3+NaX-> AgX +NaNO3
then ammonia

AgF AgCl are soluble in dilute ammonia
Agbr is soluble in concentrated ammonia
AgI isn’t soluble at all

Question 4

Oxidising ability of the halogens

Answer 4

Ability to act as an oxidising agent decreases because
atomic radius increases
shielding increases
so gains electrons less easily

Question 5

Redox reaction of I- with H2SO4 and what the observations are

Answer 5

reduces H2SO4 (+6) to form SO2 (+4), S (0) and H2S (-2)
2I-,->I2+2e-
2H+,+H2SO4+2I-,->I2+SO2+2H2O

H2SO4+6e-+6H+->S+4H2O
6H+<+H2SO4+6I-,->S+4H2O+3I2
S shows as a yellow solid

H2SO4+8H+,+8e-,->H2S+H2O
H2SO4+8H+,+8I-,->4I2+H2S+4H2O
H2S smells like rotten eggs and I2 is a black solid and purple gas

Question 6

Br- redox reaction with H2SO4 and observation

Answer 6

Reduces H2SO4(+6) to SO2 (+4)
H2SO4+2e-+2H+->SO2+2H2O
2Br-,->Br2+2e-

2H+,+H2SO4+2Br-,->Br2+SO2+2H2O

SO2 is choking gas
Br2 is Brown gas

Question 7

acid base reaction with halides and H2SO4

Answer 7

2NaF+H2SO4->Na2SO4+2HF

misty fumes is HX (x is halide)

Question 8

halogen appearances at room temperature

Answer 8

F2=pale yellow gas
Cl2=pale green gas
Br2-orange liquid
I2= purple black solid