Chemistry core practical 4

Question 1

Aim

Answer 1

To investigate the relative rates of hydrolysis comparing chloroalkanes, bromoalkanes and iodoalkanes

Question 2

Water bath

Answer 2

Set up a water bath to 50°c

Question 3

Preparing halogenoalkanes

Answer 3

Fill 3 test tubes with 5 drops of different halogenoalkanes in each
Place bung on top loosely

Question 4

Preparing silver nitrate solution

Answer 4

Pour 5cm3 silver nitrate solution into 3 separate test tubes

Question 5

Controlling for temperature

Answer 5

Place all 6 test tubes into 50°c water bath and wait until it reaches 50°c

Question 6

Measuring rate of hydrolysis

Answer 6

Add silver nitrate solution to one halogenoalkane and time how long it takes for a precipitate to be formed
Repeat for other halogenoalkanes

Question 7

What precipitate is formed when adding silver nitrate?

Answer 7

A silver halide eg silver chloride
Which halogen had been substituted with OH from water to form this silver halide

Question 8

What is acting as the nucleophile (electron pair donor) to hydrolyse the halogenoalkanes?

Answer 8

Water in the silver nitrate solution

Question 9

Why use ethanol?

Answer 9

To dissolve halogenoalkanes so they can react with water

Question 10

Why can water act as a nucleophile?

Answer 10

Contains a lone pair of electrons on oxygen a to be donated

Question 11

Why is water used as a nucleophile here and not hydroxide compound?

Answer 11

Because white precipitate formed instantly = not long enough to time to record

Question 12

What precipitate is formed fastest in terms of halogen atom?

Answer 12

Silver iodide because the carbon-iodine bond is the weakest due to longest bond length so faster rate of hydrolysis

Question 13

What precipitate is formed fastest in terms of primary, secondary, tertiary halogenoalkane?

Answer 13

Tertiary