Lab 11

1
Lab 11 Electrolytes and Conductivity
Date
Purpose
To determine if a solution is an electrolyte.
Chemical Background
Aqueous (aq) solution with water as the
solvent. Electrolyte solution that conducts
electric current. When an ionic solid dissolves
in water, the solid dissociates (splits) into
cations anions. NaCl(s) ? Na(aq)
Cl-(aq)
2
Experiment
1. Set up a conductivity circuit as
shown. 2. Test each of the following
solutions. 3. Dissolve a small scoop of each
solid in distilled water. 4. Wipe dish and test
leads clean for each new solution. 5. Discard
all solutions in the drain except the last 2.
3
Solution Formula Conductivity (Strong, Week, Non)
Pure Water
Tap Water
Sodium Chloride (aq) NaCl
Potassium Chloride (aq) KCl
Sugar (aq) C12H22O11
Baking Soda (aq) NaHCO3
Epsom Salt (aq) MgSO4
Ethanol (aq) C2H5OH
Vinegar (aq) CH3COOH
4
Analysis

1. Which substances are most likely to possess
   ionic bonds?
2. If a certain amount of NaCl was dissolved in
   water, how would the number of Na ions compare
   to the number of Cl- ions?

Results This space is for YOUR statement that
should summarize what an electrolyte is AND which
of the solutions you used were electrolytes.
5
Questions

1. Does this experiment give qualitative or
   quantitative conductivity results?
2. Explain why some of the solids conduct current
   when they are dissolved in water.
3. Why was it important to dissolve the solids in
   distilled water rather than tap water?
4. Pure water is not an electrical conductor. So
   why should we be careful with electricity around
   water?
5. Gatorade (and other sports drinks) advertise that
   they have electrolytes that will replace those
   lost during exercise. In terms of the nervous
   system, why is it important to replace the
   electrolytes?