Part 2 Analysis of the silver colloid 3, 4
Collect five clean dry glass vials. Add 5 mL of the silver solution to each of the five vials. Add 10 drops of 1M NaCl, 1 M HCl, 1 M NaOH, and 1 M glucose to each vial respectively with stirring. Clearly label the vials. Compare the appearance of the silver colloid in each of the vials. Record any changes in the colloid between the vials.
Measure the pH of all five vials. How does the addition of an ionic substance change the pH of the colloid solution? How does the appearance of the colloid change as you add different types of solutions (acids, bases, salts, sugar)? Of the solutions that induced a change in the appearance of the colloid solution, what do they have in common?
Dilute 2 mL of the original silver colloid solution with 10 mL of DI water. Using the HP spectrophotometer record a UV-Vis spectrum from (300 to 800 nm) of the colloid solution (remember to first take a blank spectrum with DI water.) Then add 0.100 mL (~4 drops) of electrolyte solution, you can choose either the acid, base or salt. Be sure to mix the solution in the cuvette after the addition of the electrolyte. Record a spectrum after the addition of the electrolyte at a time interval of 5 minutes. Compare the maximum wavelength of both spectra, and propose a theory for what is happening to the colloid in the solution. Remember to record the absorbance value for each lmax as well as any other changes you observe in both the solution and spectra.