Today we tryed a new practicle with the year 10's from the new GCSE scheme of work.
Only its not working as it should, and the guide for the lesson is tbh... rubbish
The lesson is looking into saturated and unsaturated fats and oils using bromine water
The bromine water strength is 1cm3 bromine in 250cm3 de-ionised water and the fats/oils being tested are olive oil, sunflower oil, margerine, butter, dripping and lard
The practicle says to test 0.5cm3 to 1cm3 of the oil/fat (warmed in a water bath to 50oC to melt it) with equal amounts of the bromine water. If the fat/oil is unsaturated the bromine will bond across the double bond and the solution will turn clear. If the bromine water is added to a saturated fat/oil the bromine can not bond as there are no double bonds and the solution will remain brownish due to the bromine water.
Now it also states that the results should be as follows:
1. olive oil - clear - unsaturated
2. sunflower oil - clear - unsaturated
3. margrine - clear - unsaturated
4. butter - clear - unsaturated
5. dripping - brown - saturated
6. lard - brown - saturated
The results we got were fine for 1 and 2... 3 and 4 however are not clear to begin with... so how do you tell?
Also 5 and 6 went clear... meaning dripping and lard and unsaturated
Anyone got any ideas why this is happening?
Is the hotwater bath effecting the fat/oil chaning its properties
Is the warm fat/oil splitting the diatomic structure of the bromine thereby making it colourless?
Do we need to add more bromine and less fat/oil?
Cheers people
Only its not working as it should, and the guide for the lesson is tbh... rubbish
The lesson is looking into saturated and unsaturated fats and oils using bromine water
The bromine water strength is 1cm3 bromine in 250cm3 de-ionised water and the fats/oils being tested are olive oil, sunflower oil, margerine, butter, dripping and lard
The practicle says to test 0.5cm3 to 1cm3 of the oil/fat (warmed in a water bath to 50oC to melt it) with equal amounts of the bromine water. If the fat/oil is unsaturated the bromine will bond across the double bond and the solution will turn clear. If the bromine water is added to a saturated fat/oil the bromine can not bond as there are no double bonds and the solution will remain brownish due to the bromine water.
Now it also states that the results should be as follows:
1. olive oil - clear - unsaturated
2. sunflower oil - clear - unsaturated
3. margrine - clear - unsaturated
4. butter - clear - unsaturated
5. dripping - brown - saturated
6. lard - brown - saturated
The results we got were fine for 1 and 2... 3 and 4 however are not clear to begin with... so how do you tell?
Also 5 and 6 went clear... meaning dripping and lard and unsaturated
Anyone got any ideas why this is happening?
Is the hotwater bath effecting the fat/oil chaning its properties
Is the warm fat/oil splitting the diatomic structure of the bromine thereby making it colourless?
Do we need to add more bromine and less fat/oil?
Cheers people
I have no clever comical retort for that.