Group 17

Question 1

Describe and explain the trend in m.p and b.p down group 17

Answer 1

Increases.
Electrons increase
Strength of vwfa increases

Question 2

Describe and explain reactivity down group 17

Answer 2

Decreases.
Size of atom increasing
Shielding effect increasing
Distance increasing
Overweighs increase in nuclear charge
Ability to gain electrons decreases

Question 3

Uses of Br2

Answer 3

Fire extinguisher

Question 4

Uses of I2

Answer 4

Source of gamma rays for cancer treatment

Question 5

Write the ionic equation for the displacement reaction between KBr and Cl2

Answer 5

Cl2+Br- > Cl- + Br2

Question 6

Cl2 + H2——>

Answer 6

HCl

Question 7

Describe reactivity when halogens react with hydrogen down group 17

Answer 7

Reaction vigour decreases 
F2---> explosive reaction even in dark
Cl2----> explosive in sunlight
Br2----> slowly when heated
I2----> equilibrium mixture on heating

Question 8

Explain and describe theermal stability of hydrogen halides down group 17

Answer 8

B.L increases
B.E decreases
Thermal stability decreases
Acid strength increases

Question 9

Why does reaction with H2 get less exothermic down group 17

Answer 9

Bond strength of X-X and H-H decreases

But decreases in H-X bond strength more significant

Question 10

Write the equation for reaction of Cl2 with cold dilute NaOH

Answer 10

Cl2 + NaOH —-> NaCl + NaClO + H2O

Question 11

Write equation for reaction of Cl2 with hot concentrated NaOH (aq)

Answer 11

3Cl2 + 6NaOH(aq)—> 5NaCl + 1NaClO3 + 3H2O

Question 12

Write equation for reaction of Cl2 with water

Answer 12

Cl2 + H2O—> HCl(g) + HClO(g)

Question 13

Describe test for Cl- (aq) in solution

Answer 13

Add AgNO3 (aq): white ppt
Add dilute NH3 (aq): dissolves
Add concentrated NH3 (aq): dissolves

Question 14

Describe the test for Br- in solution

Answer 14

Add AgNO3 (aq): cream ppt
Add dilute NH3 (aq): insoluble
Add concentrated NH3 (aq): dissolves

Question 15

Describee the test for I- in solution

Answer 15

Add AgNO3 (aq): pale yellow ppt
Add dilute NH3 (aq): insoluble
Add concentrated NH3 (aq): insoluble

Question 16

Write ionic equation for reaction of KCl with AgNO3 (aq)

Answer 16

Ag+ + Cl- —> AgCl

Question 17

Write reaction for when AgCl dissolves in NH3

Answer 17

AgCl + 2NH3 —-> [Ag(NH3)2]+1 (aq) + Cl-

Question 18

What halid ion is the strongest R.A in group 17

Answer 18

I-

Question 19

Write an equation for reaction of NaCl with H2SO4

Answer 19

NaCl(s) + H2SO4 (l) —-> Na2SO4/NaHSO4 + HCl(g)

Question 20

Write an equation for reaction of NaCl with H2SO4

Answer 20

NaCl(s) + H2SO4 (l) —-> Na2SO4/NaHSO4 + HCl(g)

Question 21

What are the observations of reaction of NaCl with H2SO4

Answer 21

White fumes of HCl gas

Question 22

Reaction of KBr with H2SO4?

Answer 22

2KBr + H2SO4(l)—-> Na2SO4(s) + 2HBr (g)

2HBr(g) + H2SO4(l) —> Br2(g) + SO2(g) + 2H2O (l)

Question 23

Observations of reaction of NH4Br with H2SO4?

Answer 23

White fumes of HBr
Brown liquid/fumes Br2
Pungent smell of SO2

Question 24

Reaction of NaI with H2SO4?

Answer 24

2NaI + H2SO4----> NaSO4 + 2HI
2HI + H2SO4----> I2 + SO2 + 2H2O 
Or
6HI + H2SO4---->3I2 + 1S + 2H2O 
Or
HI +H2SO4----> I2 + H2S + H2O

Question 25

Observations of reaction of KI with H2SO4?

Answer 25

Very less white fumes of HI gas
Black solid/ Purple fumes of I2 
Pungent smell of SO2 
Yellow solid S 
Smell of rotten eggs H2S