Testing For Halide Ions With Silver Nitrate

Question 1

Ionic equation for adding silver nitrate to a halogenoalkane

Answer 1

Ag + + X- —> AgX

Question 2

Conditions for silver nitrate and a halogenoalkane and reason

Answer 2

Must be mixed with ethanol to dissolve the Halogenoalkane as its not soluble in water (hydrophobic).
This allows the two to mix.

Question 3

Order of reactivity of halogenoalkanes

Answer 3

• Iodo
• Bromo
• Chloro

Question 4

Why is the order of reactivity of halogenoalkanes like this?

Answer 4

• down group 7 the bond gets longer due to increased atomic radii.
• The bond therefore becomes weaker as the electrons and protons of opposing atoms are further away making the electrostatic forces of attraction weaker.
• There is increased shielding due to more electrons between the outermost or reacting electrons causing a like-like repulsion.
• This outweighs the increase in the number of protons down the table.

Question 5

What colour do chloroalkanes and silver nitrate form?

Answer 5

No precipitate is formed so a colourless solution is present.

Question 6

What colour do Bromoalkanes and silver nitrate form?

Answer 6

A faint cream-coloured precipitate.

Question 7

What colour do iodoalkanes and silver nitrate form?

Answer 7

A thicker pale yellow precipitate

Question 8

Which type of structure reacts fastest and way

Answer 8

Tertiary, then secondary then primary.

This is due to tertiary alcohols doing SN1 and primary doing SN2 which requires a higher activation energy for the transition state