Objectives:
- The learner will measure accurately both mass and volume to make correctly concentrated solutions.
- The learner will describe the correlation between concentration and conductivity in solutions.
- The learner will explain the difference between ionic and covalent compounds.
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Lesson Submitted by Troy Schuknecht
What You Need:
Each lab group will need:
- A graduated Cylinder
- Four different, cheap, non-toxic chemicals. I use Cacl2, MgSO4, Salt (NaCl) and Sucrose (C12H22O11)
- Water
- A Conductivity meter
- Any one of the following balances:
Preparation Instructions:
Provide students with introductory instruction on Molarity and conduct practice problems for how to create Molar solutions in the laboratory. Most chemistry books cover this topic.
What To Do:
Step 1: Ask students to create a data table with the following columns:
- Solvent (always water)
- Solute
- Desired concentration
- Desired volume
- Grams of solute needed
- Conductivity
Step 2: Provide students with the solvent, solute, desired concentration (1M, 2M, 3M, etc. you choose), and desired volume of the following different solutions.
- 0M solution
- 0.1 M solution of each
- 1.0 M solution of each
- 2.0 M solution of each
Step 3: Instruct them to calculate the grams of each solution using their balance.
Step 4: Accurately generate each of the solutions.
Step 5: Have them test the conductivity of each of these solutions using the conductivity meter.
Step 6: Discuss the difference between an ionic and covalent compound and the effect upon conductivity.
Step 7: Discuss the effect of concentration on conductivity.
Wrapping Up:
This is a great lab to show students in a hands-on way that various solutions have different conductivity.
Additional Resources:
Other Mass Measurement Lessons:
Measurement products that I use in my classroom lab:
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