The electro negativity of atoms Essay Example

The electro negativity of atoms Essay Example The electro negativity of atoms Essay The electro negativity of atoms Essay ApparatusThe apparatus I will use to conduct the experiment are:* 1-clorobutane (1 mol)* 1-bromobutane (1 mol)* 1-idobutane (1mol)* Silver Nitrate (0.01 mol)* Ethanol* Water Bath (Heated to 50à ¯Ã‚ ¿Ã‚ ½C* Test tubes x3* Test tube rack* Teat pipettes x3* Burettes (1mmà ¯Ã‚ ¿Ã‚ ½) x2* Pipette fillerMethod* Set up test tubes and test tube rack* Put 1 cmà ¯Ã‚ ¿Ã‚ ½ of silver nitrate into the three test tubes using a burettes* Add ethanol(1cmà ¯Ã‚ ¿Ã‚ ½) with the other burette* Put test tubes in water bath (pre heated to 50à ¯Ã‚ ¿Ã‚ ½C) and leave for 10 minutes test tubes will be placed in water bath at the exact same timeSafetyTo make my experiment a safe one I will wear safety goggles (I also have done research into the chemicals I have using, this means I know what to do if I spill some upon my hand or on the floor) for example 1-iodobutane is a slight irritantFair TestTo make this as fair a test as possible I will use a water bath to control the temperature the bath will be heat ed to 50à ¯Ã‚ ¿Ã‚ ½C I will place all the test tubes with the mixtures in the water bath at the same time, I will ensure that they have been in the water bath for ten minutes this should ensure that they are all at the same temperature as the temperature influences the rate of reaction it is essential I do this. I will use a burette to mesure the silver nitrate and ethanol this should ensure accuracy in the volume. Human errors can affect the results; I could use a micropipette array and a data logger to take away the chance of human error, using a micropipette array would mean the halogenoalkanes are added at the time plus the drop size would be the same. The data logger will give more accurate representation of which reaction occurs fastest as you are not relying on eyesight and highly sensitive electronic equipment.ExplanationDue to halogen atom i.e. chlorine, iodine and bromine being more electronegative than the carbon the carbon halogen bond is polarised thecarbon atom is ele ctron deficient and is liable to attack fromnuceophiles with their lone-pair of electrons (e.g. OHà ¯Ã‚ ¿Ã‚ ½ ions).The carbon atom can not form more than four bonds thereforethe halogen atoms are substituted by the nuclephille and the halogen atom leaves as a halide ion. (A covalent bond forms between the carbon and the nuceophille)Mechanism nucleophilic substitutionThe OH group attacks the delta positive carbon (nucleophilic) these strength the bond between C-X bond becomes weaker. As the alcohol group approaches the carbon, the negative bonds (in hydrogen bonds) start to move away from the OHà ¯Ã‚ ¿Ã‚ ½ as they are being repelled, the final structure is opposite to the originalPredictionBondBond Enthalpy (kJ molà ¯Ã‚ ¿Ã‚ ½Ãƒ ¯Ã‚ ¿Ã‚ ½)C-Cl340C-Br280C-I240If I were to base the experiment on the electro negativity of atoms I would expect the 1-chlorobutane to react the fastest due to its high polarity (having more ability to attract electrons) the order I would expect is C-Cl fi rst then C-Br and finally C-I but as the experiment is actually based on bond enthalpies 1-chlorobutane should take the longest to react as it has the highest bond enthalpy.Based on this table of bond enthalpies (right) I would expect 1-iodobutane would react fastest as it has a lower bond enthalpy thus easier for bonds to be broken the order I would expect them to react in is C-Cl, C-Br, C-I