Expt 5 Ksp of calcium iodate PDF

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lab report...

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Chemistry 110

NAME __________________________________

EXPERIMENT 5

SECTION ________________________________

THE DETERMINATION OF Ksp VALUES FOR CALCIUM IODATE

DATE ___________________________________ INSTRUCTOR _____________________________

OBJECTIVES: The extent to which a sparingly soluble salt dissolves in water is frequently indicated in terms of the salt’s solubility product equilibrium constant, Ksp. In this experiment, Ksp for the salt calcium iodate, Ca(IO3)2 , will be determined, the effect of temperature on the value of Ksp will be examined, and the common ion effect will be demonstrated.

DATA & OBSERVATIONS:

0.05M Concentration of Na2S2O3 solution ________________________________ ____ 21C Temperature of (Room Temperature) Ca(IO3) 2 solution ___________________

Table 5.1

Titration of 10.00 mL aliquots of “Room Temperature” Ca(IO3)2 solutions with Na2S2O3 solution

Burette readings Final (after the indicator goes colourless)

Trial 1

19.98ml 0.01ml

Initial

19.97ml

Total Used

Trial 2

Trial 3

Trial 4

17.89ml

16.90ml

16.91ml

0.02ml

0.00ml

0.00ml

17.87ml

16.90ml

16.91ml

17.91ml Average titre* (volume used) of Na2S2O3 _____________________________________ * use only the titre values that are within 0.10 mL of one another Colour changes observed during reaction and titration _____________________________________________

deep red brown solution will gradually change to yellow __________________________________________________________________________________________ __________________________________________________________________________________________ 5c Temperature of (~5°C) Ca(IO3) 2 solution ______________________________

Table 5.2

Titration of 10.00 mL aliquots of “5°C” Ca(IO3) 2 solutions with Na2S2O3 solution

Burette readings

Trial 1

Trial 2

Trial 3

Trial 4

Final (after the indicator goes colourless)

11.70ml

7.70ml

7.20ml

7.90ml

Initial

0.03ml

0.00ml

0.02ml

0.00ml

Total Used

11.67ml

7.70ml

7.28ml

7.90ml

8.63ml Average titre* (volume used) of Na2S2O3 _____________________________________ * use only the titre values that are within 0.10 mL of one another

Table 5.3

Titration of 10.00 mL aliquots of “Room Temperature” Ca(IO3) 2 in 0.10 M Ca(NO3) 2 solutions with Na2S2O3 solution

Burette readings

Trial 1

Trial 2

Trial 3

Trial 4

Final (after the indicator goes colourless)

11.99ml

11.23ml

11.56ml

12.05ml

Initial

0.03ml

0.01ml

0.00ml

0.02ml

Total Used

11.96ml

11.22ml

11.56ml

12.03ml

11.70ml Average titre* (volume used) of Na2S2O3 _____________________________________ * use only the titre values that are within 0.10 mL of one another

CALCULATIONS (A)

Room Temperature Sample (see lab manual for calculation steps)

^ Ca(IO3)2 in water is exothermic.

Revised Summer 2019

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Chem 110 Exp #5 Ksp for Calcium Iodate

(B)

5 oC Sample

Because Ca(IO3)2 in water is exothermic, temperature decrease the solubility will reduce

(C)

Room temperature, in 0.10 M Ca(NO3) 2 sample

Because Ca 2+ incon increase will toward the right side, so that will increase the speed of solubility of Ca(IO3) 2.

Revised Summer 2019

3

Chem 110 Exp #5 Ksp for Calcium Iodate

Table 5.4

Results table for Ca(IO3)2 solubility [ Ca2+]

[IO3- ]

Ksp

Room Temperature Sample 5 oC Sample Room temperature, in 0.10 M Ca(NO3) 2 sample

N/A

N/A

QUESTIONS: 1.

From the change in solubility with temperature, deduce whether the process of dissolving Ca(IO3)2 in water is exothermic or endothermic. Explain your reasoning, referring to your results.

Ca(IO3)2 in water is exothermic.

2.

Was the solubility of Ca(IO3)2 affected by the presence of Ca(NO3)2? In what way? Explain, using evidence from your results. Yes, because Ca 2+ ion increase will toward the right side, so that will increase the speed of solubility of Ca(IO3) 2.

Revised Summer 2019

4

Chem 110 Exp #5 Ksp for Calcium Iodate

SOURCES OF ERROR: Example: Incorrect reading of volumes Miss the change of color No reading at eye-level Not mix solution properly

CONCLUSIONS: Ca(IO3)2 in water is exothermic,no matter change the temperature or add different ions will change the Ksp of Ca(IO3)2 . Also, the Ksp is the equilibrium constant for the process by which a solid dissolves to form ions in solution.

Revised Summer 2019

5

Chem 110 Exp #5 Ksp for Calcium Iodate...