Calculating Concentrations in a Saturated Solution of CaCl(2) and Ca(OH)2

  • Thread starter Thread starter sergey_le
  • Start date Start date
  • Tags Tags
    Ion
Click For Summary

Discussion Overview

The discussion revolves around calculating the concentrations of calcium ions in a saturated solution of CaCl2 and Ca(OH)2, based on experimental data from a lab. Participants explore the implications of pH measurements and the solubility product constant (Ksp) of Ca(OH)2 in their calculations.

Discussion Character

  • Technical explanation, Debate/contested, Experimental/applied

Main Points Raised

  • One participant describes their lab experiment, noting the preparation of a saturated solution and the measured pH, leading to a calculated OH- concentration of 0.027 M.
  • The participant references a previous lab report that calculated calcium concentration using a 1:2 ratio of OH- to Ca2+ ions and the concentration derived from CaCl2.
  • Another participant questions the validity of the previous lab report's approach, suggesting that the Ksp of Ca(OH)2 should be considered in the calculations.
  • There is a challenge regarding whether the initial participant's understanding or the previous report's method is correct, with a suggestion that the report's approach may be flawed.
  • A later reply indicates that the report's approach appears incorrect but does not provide an alternative calculation method.

Areas of Agreement / Disagreement

Participants express disagreement regarding the method used in the previous lab report for calculating calcium concentration. There is no consensus on the correct approach to the calculations, and multiple viewpoints are presented.

Contextual Notes

Participants have not resolved the implications of the Ksp of Ca(OH)2 on the calculations, and there are uncertainties regarding the assumptions made in the previous lab report's methodology.

sergey_le
Messages
77
Reaction score
15
Summary:: finding concetrations

[Thread moved from the technical forums]

i did a lab experiment and I'm a little confused about what i should do.

i got a solution of CaCl(2) 1.5 gr and Ca(OH)2 5gr in 100ml that i prepared 2 weeks ahead
. after filttering the solution i got a saturated solution of CaCl(2) +Ca(OH)2.i tested the pH of it.(it is 12.43)

from the Ph value i got that OH concetration is 0.027M. the next quetion i need to answer is whet is the concentration of Ca. so i was seeing a lab report from a year ago, and to calculate the Ca consentration they first used the OH saturation (1:2) ratio. so 0.027/2=0.0135M. after that they calculated the amount of Ca from the CaCl(2) salt (1.5gr/110.98(gr/mol)=0.0137m/0.1l) which is 0.137M. they concluded that the ca consentration is 0.137+0.0135M.

i don't understand why. we calculate the consentration for a saturated solution, so there are no Ca ions from the CaCl(2) just floating and reacting...they already reacted and the axcess already sunk and turned to a solid, no?
 
Last edited by a moderator:
Physics news on Phys.org
Nope, doesn't look like a correct approach to me.

Hint: what is the Ksp of Ca(OH)2?
 
Borek said:
Nope, doesn't look like a correct approach to me.

Hint: what is the Ksp of Ca(OH)2?
my approach is wrong or the one in the lasts year lab report?
 
Sorry, report approach looks wrong.

Technically you just expressed your concerns but never stated what would be your approach to calculations :smile:
 

Similar threads

Chemistry What precipitates form by mixing 2 saturated solutions?
  • · Replies 2 ·
Replies
2
Views
2K
Understanding HCl + Ca(OH)2 Reaction: pH?
  • · Replies 3 ·
Replies
3
Views
10K
Chemistry How to take into account autoprotolysis in weak base solution?
  • · Replies 8 ·
Replies
8
Views
2K
Where Did I Go Wrong in Calculating Hydroxide Ion Concentration?
  • · Replies 4 ·
Replies
4
Views
2K
How to Calculate Li+ Ion Concentration in Saturated Li3PO4 Solution?
  • · Replies 2 ·
Replies
2
Views
2K
Chemistry: Finding Ksp for Ca(OH)2
  • · Replies 3 ·
Replies
3
Views
6K
Water Hardness. Calculating Calcium.
  • · Replies 1 ·
Replies
1
Views
3K
Acid-Base Reactions: Did the Solutions Neutralize Each Other? | Homework Help
  • · Replies 2 ·
Replies
2
Views
3K
Chemistry: Ksp calculation confusion
  • · Replies 2 ·
Replies
2
Views
10K
What Is the Final Concentration of Hydroxide Ions After Reaction?
  • · Replies 15 ·
Replies
15
Views
2K