A. Molar solubility and Solubility Product of Calcium Hydroxide 1. Volume of sat
ID: 909021 • Letter: A
Question
A. Molar solubility and Solubility Product of Calcium Hydroxide 1. Volume of saturated Ca(OH)2 solution (mL) 2. concentration of standardized HCI solution (mol/L) 3. Buret reading, initial (mL) 4. Buret reading, final (mL) 5. Volume of HCI added (mL) 6. Moles of HCI added (mol) 7. Moles of OH^- in saturated solution (mol 8. [OH^-] equilibrium (mol/L) 9. [Ca^2+], equilibrium (mol/L) 10. Molar solubility of Ca(OH)2 (mol/L) 11. Average molar solubility of Ca(OH)2 (mol/L) 12. Ksp of Ca(OH)2 13. Average Ksp 14. Standard deviation of Ksp 15. Relative standard deviation of Ksp(%RSD) Calculations for Trial 1.Explanation / Answer
Solution:
The volume of saturated Ca(OH)2 solution (mL) is 25.00
Step 1) The chemical equation:
Ca(OH)2 <===> Ca2+ + 2OH¯
Step 2) The Ksp expression:
Ksp = [Ca2+] [OH¯]2
Step 3) Use titration data to determine moles of OH¯ in the 25.0 mL sample (Remember, every one H+ neutralizes one OH¯.):
molarity = moles ÷ volume (in liters)
0.0250 mol/L = x ÷ 0.02250 L
x = 0.0005625 mol
Step 4) Use moles of OH¯ and sample volume to determine [OH¯]:
0.0005625 mol / 0.02500 L = 0.0225 mol/L
Step 5) Determine [Ca2+]:
it is exactly half the [OH¯]. This is because of the 1:2 molar ratio from the balanced equation.
Step 6) Calculate the Ksp for Ca(OH)2
Ksp = (0.01125) (0.0225)2 = 5.70 x 10¯6 mol-3 dm
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