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Introduction:
In this lab students will use a clean massed strip of zinc placed
in a saturated solution if lead (II) chloride to determine the solubility product constant of the lead (II) chloride. By finding
the change in mass of the zinc strip, and knowing the exact volume of saturated solution used, the concentration of the saturated
solution can be determined which will allow the students to calculate the Ksp of PbCl2.
Estimated time to complete lab:
This lab requires part of two
classes. The portion of the lab completed on day 1 will require about 15-20 minutes of class time. Day 2 will require 5-10
minutes of class time for experimentation and an addition 10-15 minutes to perform the calculations and complete the write-up.
Equipment Required:
- 1-2 L of saturated PbCl2 solution per class.
For each group:
- 250mL beaker
- 50.0mL or 100.0mL graduated cylinder
- Balance (shared)
- Strip of zinc metal (cleaned)
- Steel wool
Safety Concerns:
- Wear safety glasses at ALL times during the lab.
- Be aware of any cracked/chipped glassware.
- All lead compounds are poisonous. Handle appropriately.
- Wash hand after use.
Clean Up Concerns:
- The lead metal produced should be collected and disposed of according to your Board’s guidelines
for chemical disposal.
- Wash hands after use.
What Can Go Wrong:
- Some saturated lead (II) chloride solutions have acid added to
them to prevent the hydrolysis of the lead (II) ion. This acid will react with the zinc and cause the loss of mass in the
zinc to be too large, throwing the value of the solubility product constant off by magnitudes of 10. Prepare your own fresh
saturated solution for this activity.
Student Lab Sheet as a Word Document:
click here to download file
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Click here to return to the Lab Manual Contents page.
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