Ksp of Calcium Hydroxide

Vernier pH sensor, lab quest, ring stand, 100-mL beaker (2), 250-mL beaker (2), 50-mL graduated cylinder (2), 50-mL burette, indicator solution, burette clamp, filter paper, filter funnel, magnetic stirrer, magnetic bar.

Procedure

 Measure out 15-mL of filtered solution of saturated calcium hydroxide into a 250-mL beaker  Set up a beaker of Ca(OH) 2 solution on a magnetic stirrer  Obtain about 200-mL of 0 M HCl solution. * Handle with care*  Set up the burette, rinse and fill with 0 M HCl solution  Connect pH sensor to lab quest and calibrate  Conduct titration carefully  Before adding HCl, click the play button to begin data collection, once pH has stabilized, click keep

MA= 0 M

MB = 0 15 MB= 0 M For an equivalent point to be attained, the moles of acid are equal to the moles of base. This can help determine the concentration of an unknown solution. The volume of Ksp CaOH was 15mL this value was derived from the Ca(OH) 2 prepared by the professor before HCl was titrated against the solution.

  1. Calculate the [Ca2+]. Ca(OH) 2 <------> Ca2+ + 2OH- [Ca2+] = 0 2 = 0 M For every 1 mole of Ca2+ released, 2 moles of OH- is released as calcium hydroxide is dissociated in water. Therefore, the molarity of Ca2+ is half the molarity of OH-
  2. Calculate the Ksp for calcium hydroxide: KSP = [Ca2+][OH-] 2

=[0][0] 2

Ksp = 5 x 10- 4. Find the accepted value of the Ksp for calcium hydroxide and compare it with your value. Discuss the discrepancy and suggest possible sources of experimental error. Accepted value for Ksp for sodium hydroxide is 5 x 10-6. The accepted value of the Ksp is way off from the accepted value. This discrepancy might have been caused by misreading the calcium hydroxide added into the beaker for titration. Sources of error includes not stirring the solution properly when HCl was added to the solution. Another source of error is not waiting for the pH values to remain steady before clicking keep. This might have allowed the experimenter to get a wrong equivalence point. To avoid such errors in the future, the accurate reading of the calcium hydroxide before adding it into the beaker. Other industries that use Ksp of calcium include the manufacturing industry, Ca(OH) 2 is a colorless crystal, when mixed with CaO and water, it gives a white powder. Ca(OH) 2 can be produced in large quantities by the thermal decomposition of limestone and an exothermic reaction of CaO and H 2 O ((Libretexts, 2020)

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