Apparatus
.retort stand and clamp
.burette
.pipette
.small beaker containing HCl
.small beaker containing NaOH
.funnel
.polystyrene cup
thermometer
Method
1)collect apparatus
2)pipette 25cm3 of acid
3)put the acid in to the polystyrene cup
4)fill burette with NaOH
5)put thermometer in polystyrene cup and note temperature
6)add 5cm3 of NaOH, stir the solution and note temperature
7)keep adding NaOH at 5cm3 intervals, stir and note temperature between each addition of NaOH
Displaying the Results
Results should be displayed in a graph and a table like the one shown below:
Safety
The following safety precautions should be observed when carrying out this experiment:
.assemble apparatusin the centre of an uncluttered bench
.take care as acid is being used
.wear goggles
Conclusion
As expected, the temperature of the solution increased with the volume of NaOH until a point, when the temperature is 28.4 oC and the volume of NaOH is about 28cm3. At this point, the acid has been neutralised, the reaction is over, so no more heat is given out. More NaOH is added which lowers the temperature of the solution. We know the molarity of the acid (1.0m), the volume of the acid (25cm3) and we have worked out the volume of the NaOH (28cm3). Using m1 x v1=m2 x v2 we can work out the molarity of the alkali.
molarity of acid molarity of alkali
multiplied by = multiplied by
volume of acid volume of alkali
25 = m2 x 28
m2 =25/28
m2 =0.9m
I have know got an approximate value of the molarity of the alkali at 0.9m.
Evaluation
I think that the experiment has worked well, because the end result is the one that I expected to happen and I was able to work out the molarity of the alkali. If I was to do it again I would add the NaOH in intervals of 3cm3 instead of 5cm3 to increase accuracy.
RESULTS
