Calorimetry other ü Random arrangement Movement of particles

Calorimetry is the process of determining
the amount of heat is released or absorbed during a chemical reaction. Also
knowing the change in heat can be determined whether or not the reaction will
be exothermic (releases heat) or endothermic (absorbing heat).  (https://chem.libretexts.org/Core/Physical_and_Theoretical_Chemistry/Thermodynamics/Calorimetry)

 

Aim: to
measure the cooling rates of stearic acid and paraffin wax.

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Equipment:

 

ü  Mercury Thermometer

ü  Digital Thermometer

ü  Stopwatch

ü  Beakers x2

ü  Test tubes

ü  Test tube rack

ü  Water bath

ü  Spatula

 

Calibration of equipment:

 

Thermometer,

 

The thermometers were calibrated by using
two types of thermometers, which were a digital thermometer and mercury, so
that it had given a more accurate reading towards the final answer. The
thermometers were examined inside icy water and boiling water. The most exact
thermometer was the mercury thermometer because it had given more accurate and
precise readings compared to the digital thermometer. The thermometer was held
from the top and not from the bottom so that the readings were taken
accurately.

(http://www.bbc.co.uk/bitesize/ks3/science/chemical_material_behaviour/particle_model/revision/6/
) (below for the diagram)

 

 

Solid

Liquid

Gas

Arrangement of particles

ü  Dense
 
ü  Consistent pattern

ü  Dense
 
ü  Random arrangement

ü  Far apart from each other
 
ü  Random arrangement

Movement of particles  

ü  Vibrate on the spot

ü  Move around each other

ü  Move rapidly in all directions

Diagram
 
 
 
 
 
 

 

 
 
 

 

Method:

 

Begin by placing the test tubes into a
beaker containing hot boiling water. Then place a thermometer inside the test
tubes, and record the start temperature. Next remove the thermometer from the boiling
tubes and allow the hot boiling water to cool. Then immediately and with care
take out the test tubes out of the water bath and start the stopwatch for
approximately 15-20 minutes. Then record the temperatures after every 30
seconds at set intervals, for about 15-20 minutes. This procedure should be
done the same for Stearic acid.

 

Calculations:

 

The table below is showing that the
thermometers were calibrated in two different places, Icy water and Boiling
water,

 

 

 

 

Icy water

Boiling water

Digital thermometer

-0.3

                    95.0

Mercury thermometer

              -3

                    96.5

 

The reason why both thermometers were
calibrated was to ensure which thermometer had given the most accurate and
precise readings when finding the cooling rates of paraffin wax and stearic
acid. The thermometer which had given the most accurate readings was the
mercury thermometer, this was due to

 

Add graph

 

 

Add table for absorbance

 

Results and analysis:

 

Paraffin Wax table,

 

Temperature

Time (Every 30 secs)

87

Start temperature

75

30 sec

70

1 min

66

1 :30 sec

63

2 min

60

2:30 sec

57.5

3 min

55.2

3:30 sec

53.1

4 min

53

4:30 sec

51

5 min

50.7

5:30 sec

50.4

6 min

50.1

6:30 sec

50

7 min

49.7

7:30 sec

49.5

8 min

49

8:30 sec

48.7

9 min

48.5

9:30 sec

47.5

10 min

47

10:30 sec

47

11 min

47

11:30 sec

46.8

12 min

46.7

12:30 sec

46.6

13 min

46.5

13:30 sec

46.4

14 min

46.2

14:30 min

46

15 mins

 

 

Paraffin wax

Temperature

Start point

87

End point

46

 

Stearic acid table,

 

Temperature

Time

80

Start temperature

79

30 sec

66

1 min

65

1:30 sec

61

2 min

59

2:30 sec

57

3 min

56

3:30 sec

55

4 min

55

4:30 sec

54.9

5 min

54.8

5:30 sec

54.8

6 min

54.8

6:30 sec

54.8

7 min

54.8

7:30 sec

54.8

8 min

54.8

8:30 sec

54.8

9 min

54.7

9:30 sec

54.7

10 min

54.7

10:30 sec

54.6

11 min

54.6

11:30 sec

54.1

12 min

54.1

12:30 sec

54.1

13 min

54.1

13:30 sec

54.1

14 min

54

14:30 sec

54

15 min

 

Stearic acid

Temperature

Start point

80

End point

54

 

 

Conclusion:

 

State the cooling rate of stearic acid

State the cooling rate of paraffin wax

 

 

Accuracy and Evaluation:

 

During the practical accuracy was measured
in several different ways,

 

The first way I stayed accurate was by
holding the test tubes which had contained (paraffin wax or stearic acid) from
the top. The reason why I never held the test tubes from the bottom was because
if the test tubes were held from the bottom then this would affect the
temperature of the paraffin wax and stearic acid.

 

Another way I began by staying accurate was
by not letting any unwanted heat lost, from the surrounding nearby. This was
managed by have the windows closed, covering the windows with blinds.   

 

 

 

 

 

 

 

 

 

 

 

 

References:

 

Own notes

 

 

http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway_pre_2011/carbon_chem/8_energy3.shtml