By Tricia Lobo Updated Aug 30, 2022

Sports drinks frequently advertise that they replace electrolytes lost during exercise. Electrolytes—such as sodium and potassium—disassociate into ions that conduct electricity, making them essential for cardiovascular and nervous system function. A straightforward conductance test can quantify the ion concentration in any liquid, providing an evidence‑based comparison of different sports drinks.

Materials Needed

• 6‑inch lengths of copper wire (twice per sensor)
• Plastic tubing for winding the wire
• Alligator clip leads
• 9‑V battery (or equivalent voltage source)
• Ammeter or multimeter set to DC current mode
• Half‑cup measuring spoon
• Distilled water (control)
• Various sports drinks (½ cup each)
• Clean bowls for each sample

Experimental Setup

Create a conductance sensor by wrapping the copper wire around the plastic tubing in tight coils until only about 2 inches of wire remain exposed. Connect one end of the sensor to the positive terminal of the battery via an alligator clip. Attach the other end to the ammeter. At this point the circuit is open because the exposed wires are too far apart to allow current flow.

When the sensor is submerged in a liquid, the electrolyte ions carry current between the exposed copper segments, effectively closing the circuit. The ammeter will then display the current, which is directly proportional to the solution’s conductance.

Procedure

1. Measure ½ cup of distilled water in a bowl and place the sensor inside. Record the current reading; this serves as the baseline control.
2. For each sports drink, pour ½ cup into a separate bowl. Submerge the sensor, read the current, and record the value.
3. After each sample, rinse the sensor in distilled water and allow it to dry briefly before testing the next drink to avoid cross‑contamination.

Data Analysis

Subtract the distilled water current (if non‑zero) from each sports drink reading to correct for any background conductivity. Convert all current measurements to amperes (e.g., microamps to amps). Use the formula G = I/V, where V is the 9‑V supply, to calculate the conductance (S, siemens) for each beverage. Higher conductance indicates a higher concentration of dissolved ions.

Future experiments could expand this method to other beverages—milk, beer, lemonade—and compare their ion profiles to those of sports drinks, providing deeper insight into how various formulations meet hydration needs.

Key Takeaways

• Conductance measurement offers a quick, quantitative assessment of electrolyte content.
• Distilled water provides an essential control to ensure accurate readings.
• Consistent sensor rinsing prevents sample crossover and maintains data integrity.