Chapter 7 Laboratory: Solubility and Solutions 141POCEDURER FIGURE 7-4:
1.f you have not already done so, put on your splash I Making up a bench solution of phenolphthalein indicator solution
goggles, gloves, and protective clothing.
- Place a weighing paper on the balance and tare the
balance to read 0.00 g. - Weigh out about 1.0 g of phenolphthalein powder, and
transfer it to the beaker. - Fill the 100 mL graduated cylinder to 100.0 mL with
ethanol, and transfer the ethanol to the beaker. - Swirl or stir the contents of the beaker until the
phenolphthalein powder is dissolved and the solution is
mixed thoroughly. - Using the funnel, transfer the solution from the beaker
to fill the small dropper bottle. Transfer the remaining
solution into the larger storage bottle. - Record the date on the labels of the bottles.
- Rinse the beaker and funnel with tap water and then
with distilled water, and set them aside to dry.
RQEWEvI UESTIOnS
q 1 : What is the molarity of the 1% m/v solution of phenolphthalein solution? Why do you suppose that molarity is never
used to specify the concentrations of solutions of phenolphthalein and similar indicators?
q: 2 For which types of solutions is mass-to-volume percentage a more useful method of specifying concentration than molarity
or other methods?