Question

# Titrations of 25.00 mL aliquots of CaOH2(aq) solution (saturated at ~100 °C) with standardized 0.1020 moles∙L-1...

Titrations of 25.00 mL aliquots of CaOH2(aq) solution (saturated at ~100 °C) with standardized 0.1020 moles∙L-1 HCl(aq)

 Final Burette Reading (mL) 10.29 19.56 31.92 Initial burette Reading (mL) 0.29 10.29 21.34 Volume of HCl(aq) added 10 9.27 9.33

volume of HCL 9.3mL

 Trial 1 Trial 2 Trial 3 Final Burette Reading (mL) 15.23 23.19 31.30 Initial burette Reading (mL) 8.41 16.61 23.91 Volume of HCl(aq) added 6.82 7.30 7.39

Volume of HCL 7.35mL

[OH] = __0.1789______________ mol L-1

OH] = ___________0.0584_____ mol L-1

1. Calculate the [Ca2+] in the saturated solution and report the molar solubility of Ca(OH)2 (s) at both room and elevated temperatures.

Room temperature:

[Ca2+] = ________________ mol L-1

s = ________________ mol L-1

Elevated temperature:

[Ca2+] = ________________ mol L-1

s = ________________ mol L-1

The concentration of OH- and Ca + 2 in each trial is calculated, that of Ca + 2 is equal to the solubility:

[OH-] = Ca * Va / Vb = 0.1020 M * 10 mL / 25 mL = 0.0408 M

Trial 2: 0.0378 M

Trial 3: 0.0380 M

High temperature:

Trial 1: 0.0278 M

Trial 2: 0.0298 M

Trial 3: 0.0302 M

The concentration of Ca + 2 is calculated:

[Ca + 2] = [OH-] / 2 = 0.0408 M / 2 = 0.0204 M

Trial 2: 0.0189 M

Trial 3: 0.0190 M

High temperature:

Trial 1: 0.0139 M

Trial 2: 0.0149 M

Trial 3: 0.0151 M

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