Q.

• Arrange a simple set up as shown in the diagram above.
• The lamp will glow when circuit is complete.
• Prepare 5 % (mass/volume) solutions of cane sugar, acetic acid, sodium chloride and urea in distilled water.
• Check the electrical conductivity of these solutions using the above assembly. Compare these with that observed with distilled water.

Step 1. Build the test circuit: battery, switch, lamp, and two electrodes dipped into the test solution -- the lamp lights only when the solution completes the circuit by conducting.

Step 2. Distilled water alone barely lights the lamp, since pure water has very few ions.

Step 3. The sugar and urea solutions behave almost identically to plain water -- both are nonelectrolytes, since sucrose and urea molecules do NOT dissociate into ions in water, so they add essentially no current-carrying species.

Step 4. The NaCl solution lights the lamp brightly -- NaCl is a strong electrolyte, almost completely dissociated into mobile Na+ and Cl- ions at this 5% concentration. …

Predict the relative brightness of the test lamp for each solution based on whether the solute is a nonelectr …

• Expecting sugar or urea solutions to conduct at all, since they LOOK like they dissolve just as readily as NaCl -- dissolv …