Experiment 6: Determination of Ksp of Cuc4H4O6.

Experiment 6: Determination of Ksp of CuC4H4O6.

Results:

This experiment used known amounts of five Cu2+ containing solutions to find absorbance levels. A calibration curve was created to look up amounts of five unknown solutions using a trend line on the graph. The x-axis is the volume while the y-axis is the absorbance levels. First, only test tube 1 and 2 were used to find values. The values calculated were The initial mole of Cu2+, initial mole of C4H4O62-, equilibrium of Cu, mole of Cu2+ ppt, mole of C4H4O62- ppt, the equilibrium mole of C4H4O62-, and Ksp. The initial mole values were found by taking the original mL of solution added, converting into liters, then multiplied by 0.2 mols. The absorbance levels of test tube 1 and two were used (0.12 & 0.30 respectively) to find the volume of the Cu2+ , which is used to find the equilibrium mole of the Cu2+. The 1:1 mole ratio allows Cu2+ and C4H4O62- be compared together as equaling each other. To Find the Ksp is easy because it is the [Cu2+] and [C4H4O62-] multiplied together. The two values end up being 5.6 x 10-7 and 8.96 x 10-7. The final part of the calculations is the molar solubility of CuC4H4O6 in three different solutions (aka. Test tube 3, 4, & 5). The same method using the calibration curve is used to find the moles of each. In water, the molar solubility is 0.0009, in 0.1 M Na2SO4 is 8 x 10-5, and in 0.1 M H2SO4 is 1.8 x 10-4.

Conclusions:

After research about Ksp values and the meaning behind how soluble or insoluble, and since a higher K value means the solution will convert most of the dissolved substance into ions, that the test tube 1 is more soluble. It seems that test tube 1 had less absorbance levels, which indicates it was more transparent than others. The solubility of the three test tubes 3, 4, and 5 were all slightly higher in molar solubility. This seems to correspond with absorbance once again because these trials had low absorbance rates as a whole compared to test...