Investigating the Hydrolysis of Halogenoalkanes

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Investigating the Hydrolysis of Halogenoalkanes

Aim: To investigate the hydrolysis of halogenoalkanes

Equipment and Materials

1-Chlorobutane

1-Bromobutane

1-Iodobutane

Silver Nitrate

250cm3 Beaker

Pipette

Ethanol (2cm3 per tube)

Bunsen Burner

Tripod

Test Tubes

Stop Watch

Water Bath

Control and Variables

· Use a pipette and measuring cylinder to measure exactly 2cm3 of

ethanol into each of the three test tubes. (Make sure when using the

measuring cylinder that all the readings are taken below the meniscus)

· Heat the tubes together to ensure the same temperature

· If I allow the temperature to get too high, then the mixtures will

evaporate.

· When timing how long it takes for a precipitate to appear in each

test tube, the temperatures may fall so it is therefore advisable to

re-heat the water in the beaker at repeated intervals.

· Repeating the experiment again will help me avoid any anomalous

results. Ideally, I intend to repeat the time measurements 3 times.

Halogenoalkanes react with an aqueous solution of hydroxide ions

according to the equation:

RX + OH- Ù ROH + X- (X = Cl, Br or I)

The following experiments examine the effect on the rate of hydrolysis

when (a) the halogen is changed and (b) primary, secondary and

tertiary halogenoalkanes and a halogenoarene are used. Ethanol is used

as a common solvent for the halogenoalkane and for the silver nitrate

solution. Water (from the silver nitrate solution) is used as

hydrolysis agent in place of hydroxide ions, which tend to react too

quickly for comparisons to be made.

Environmental care:

The aqueous residues will contain the heavy metal ions of Ag and the

organic residues will contain halogenated hydrocarbons so it is

important not to dispose of any waste down the sink. Place all

residues in the marked beaker in the fume cupboard. At the end of the

practical, the two immiscible layers in the combined waste can be

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