Halogens

Question 1

Colour of cl2 in water and in hexane

Answer 1

Colourless in h20

Colourless in hexan

Question 2

Colour of Br2 in water and in hexane

Answer 2

Yellow/orange in water

Orange/red in hexane

Question 3

Colour of I2 in water and in hexane

Answer 3

Brown in water

Pink/violet in hexane

Question 4

Why do melting and boiling points increase down the group for a halogen?

Answer 4

More electrons so London forces are stronger

Question 5

Halogen with cold alkali

Answer 5

Disproportionation reaction

X2 + 2NaOH —> NaOX + NaX +H2O

Question 6

Cl2 and NaOH make bleach

Answer 6

2NaOH + cl2 —> NaCl + NaOCl (bleach) +h20

Question 7

Halogens undergo disproportionation with hot alkalis

Answer 7

Forms NaClO3 instead of NaClO

Question 8

Cl2 is used to kill bacteria in water

Answer 8

Cl2 + H2O —> HCl + HClO

HClO + H2O —> ClO + H3O

ClO kills bacteria