Iodine-starch Clock Rxn

Lab : Iodine-starch Clock Reaction
Pre-lab:
Before the lab was conducted, the concentration of the Iodate ions to be in the mixture made by dissolving specific volumes of solution A with a constant concentration and water was calculated using the dissolution formula: C1V1 = C2V2
Sample Calculation 1: Concentration of the Iodate ions:
For mixture 1: C2 = C1V1/ V2 = (0.020mol/L) x (0.003L)/(0.01L) = 0.006mol/L
The same calculations were used in the calculating of the concentrations of the iodate ions in the mixture which is included in the table below.

Observations
Table 1: Data table of the elapsed time during the colour change in the reaction recorded by the 5 groups that conducted the experiment
Mixture
Volume of sol A
(mL)
Volume
Of H2O (mL)
[IO3-] conc.(M)
Volume of sol B (mL)
Elapsed
Time(s)
Group 2 (s)
Group 3 (s)
Group 4 (s)
Group 5 (s)
1
3
7
0.006
10
3.91
4.10
4.44
3.47
3.94
2
4
6
0.008
10
2.47
2.91
2.09
3.12
3.13
3
5
5
0.010
10
2.09
1.69
2.00
2.59
3.09
4
6
4
0.012
10
2.01
1.53
2.08
1.91
1.85
5
7
3
0.014
10
2.40
1.37
1.75
2.78
2.69
6
8
2
0.016
10
1.19
1.41
1.41
1.75
1.50
7
9
1
0.018
10
1.05
1.63
1.21
2.22
1.30
8
10
0
0.020
10
0.31
2.41
1.06
1.41
1.24

Table 2: Qualitative observations of the solutions:
Solution A (KIO3)
Clear, colourless, odourless solution
Solution B (NaHSO3)
Translucent white cloudy solution, some flakes settle at bottom of beaker
Solution formed
Dark bluish-black coloured solution with flaky dark precipitate.

Analysis
Table 3: Data analysis
Sample calculation 2: Determining the average reaction time:
For mixture 1: Average = sum of reaction times/number of trials = [3.91 + 4.10 + 4.44 + 3.47 + 3.94]/5 = 3.97s
Similar calculations were done to produce the average reaction time values on the chart to the left.

Figure 1: