• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Chemistry Plan Halogenoalkanes

Extracts from this document...


Rates of reaction of halogenoalkanes Aim: To compare the rate of displacement of the halide ion varies with respect to the C - X bond. C is the carbon atom and X being the halogen. This is a nucleophilic substitution reaction. Background Knowledge: Halogenoalkanes are alkanes that have one of the H atom replaced with a halogen atom. They are classified according to the number of carbon atoms bonded to the carbon atom which has the halogen atom bonded to. They are primary, secondary and tertiary. A nucleophile is an electron donor; it has one or more lone pairs of electrons which it donates to the carbon atom which has a slightly positive charge due to the difference in electronegativity between the carbon and the halogen atom resulting in the C atom susceptible to attack by an electron rich species (a nucleophile). ...read more.


Bond Bond Enthalpy (KJ/mol) C - Cl + 346 C - Br + 290 C - I + 228 Prediction: As you go down from Cl to I the bond enthalpy decreases. The bond enthalpy of the C- Cl bond is the strongest and C - I the weakest. This means that less energy is needed to break the C - I bond than needed for C - Cl. Bromine is more reactive than C - Cl, but less reactive than C - I. Therefore C - I will react faster than C - Br which will react faster than C - Cl. Order of reactivity: (C - Cl) < (C - Br) < (C - I) Equation: R - X + OH- R - OH + X- (R - CnH2n-1, X - Halogen) R - OH + :X- Apparatus: - 1-chlorobutane - 1-bromobutane - 1-iodobutane - Aqueous silver nitrate - 0.02moldm-3 - Ethanol - Water bath (50oC) ...read more.


Note the results in the table: Halogenoalkane Precipitate colour Time taken (s) Average Time (s) First Second Third 1-chlorbutane Faint White 1-bromobutane White 1-iodobutane Yellow Why my method works: All the variables have been carefully controlled. At low temperatures the rate was slow, so the procedure was carried out in a higher temperature. The temperature was kept constant by using the water bath. Also the chemicals were left in the bath to reach the baths temperature. The volumes were carefully controlled by using precise apparatus. The nucleophile was reliable and less hazardous. Ethanol was used as a solvent. The OH- ions for the reaction are obtained from the aqueous silver nitrate. Hazards and precautions: Halogenoalkanes: - Highly Flammable - Irritant - Harmful Silver Nitrate - Harmful - Dangerous to the environment - Oxidising - Corrosive The chemicals are kept away from any source of fire. All handled in a safe manner. Skin and eye protection has to be worn i.e. lab coats, gloves and goggles. All the glassware should be handled safely and any breakages should be notified. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Organic Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Organic Chemistry essays

  1. Find the enthalpy change of combustion of a number of alcohol's' so that you ...

    would transfer to the water meaning that my results would be more accurate and the enthalpy change of combustion value will be more accurate. An alternate thing you could do is use a non-burning wick that can only deliver the alcohol but does not burn itself.

  2. The aim of this experiment is to investigate the enthalpy change of combustion for ...

    O H H O H H From this I can see that only one C-C bond is broken however now four C=O bonds are formed. As the carbon chain length increases by one there is an increase in one C-C bond, two C-H bonds and 1.5 O=O bonds.

  1. Comprehensive and Detailed Chemistry notes

    - Thus a high temperature causes a decrease in the yield of ammonia - Le Chatelier's principle states a low temperature favours a higher yield of ammonia. * explain why the Haber process is based on a delicate balancing act involving reaction energy, reaction rate and equilibrium * explain that

  2. Rates of Halogenoalkanes

    I predict that as the halogen is changed down the group, i.e. from chlorine to bromine to iodine, the rate of hydrolysis will increase. This is because the bond enthalpy of a carbon-iodine bond is lower than that of a carbon-bromine bond, which is subsequently lower than that of a carbon-chlorine bond.

  1. Compare the enthalpy changes of combustion of different alcohols

    Check that heat proof mats are in place to act as a draught excluder and also place on top of work surface so not to damage it. Place the spirit burner on heat proof mat and surround with 3 other heat proof mats as shown in the diagram. 7)

  2. The Preparation of 1-bromobutane

    Small funnel with cotton wool plug 7. Distillation head 21. Glass rod 8. Clamp and stand 22. Small beaker 9. 250cm3 beaker (for water bath) 23. 0-110°C thermometer and holder 10. Conc. Sulphuric acid (10cm3) 24. Specimen tube 11. Anti-bumping granules 12. Reflux condenser 13. Guard tube containing soda lime 14.

  1. Planning Coursework - Investigation of rate of hydrolysis of halogenoalkanes

    To sum up, the measurements going to be taken in this experiment will be the time taken for precipitate to form which blocks out the colour of the black background paper. Note that the unit of the measurements will be in seconds.

  2. Rates of reactions of halogenoalkanes

    The bond enthalpy decreases down the group. Bond Bond enthalpy (kj mol -1) C-F 467 C-Cl 340 C-Br 280 C-I 240 The decreasing bond enthalpies going down group 7 of the periodic table show that the carbon-halogen bonds are easier to break at the bottom of the group because they are much weaker.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work