Electrolyte Challenge: Orange Juice Vs. Sports Drink

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Abstract

Objective

To investigate whether or not a sports drink provides more electrolytes than orange juice.

Credits

David Whyte, PhD, Science Buddies

This project is based on the following 2008 California State Science fair project, a winner of the Science Buddies Clever Scientist Award:
Yaeger, T.O. Jr. (2008). Electrolyte Madness.

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Introduction

"Just do it!" You have probably heard that slogan, and there is no doubt that exercise is a key part of staying healthy. But exercising depletes the body's stores of fluids and minerals, which must be replaced. Most experts agree that if you are engaged in light to moderate exercise, drinking a glass or two of water should do the trick. But if you are exercising strenuously, you also need to replenish some of the salts that your body loses through sweat. These salts, or electrolytes, are found in most sports drinks.

What advantages does a sports drink have over water? Water provides the liquid you need to avoid dehydration, but it does not have electrolytes. An electrolyte is a substance that will dissociate into ions in a solution. The ions in the solution give it the capacity to conduct electricity. Electrolytes, such as sodium and potassium, are present in sweat. Chloride, calcium, and phosphate ions are also electrolytes.

The proper concentration of electrolytes in your blood is essential to your health. Your cardiovascular and nervous systems, to name just two, require electrolytes to function well. Differences in the concentration of sodium and potassium inside and outside of cells allow your nerve and muscle fibers to send electrical impulses (which is how these cells communicate and get your body to react and move).

Your body keeps the concentration of the various electrolytes in its fluids within a narrow range, and this process depends on consuming enough water and electrolytes. The maintenance of electrolytes within this narrow range is due to the body's homeostatic mechanisms, which control the absorption, distribution, and excretion of water and its dissolved electrolytes.

But can you get your electrolytes from natural juices, such as orange juice? Yes and no. One problem with juices is that many have relatively high concentrations of carbohydrates, which is fine for your morning drink, but not ideal for rehydrating during exercise. High levels of carbohydrates add useless calories and require water for digestion.

To measure the electrolytes in this science project, you will use a multimeter. A multimeter is an electronic device that measures voltage, current, and resistance. For this project, you will use just the ammeter part of the multimeter. An ammeter measures current.

How can you use an ammeter to measure the concentration of electrolytes? You will use it to measure conductance, which is proportional to the electrolyte concentration. Because electrolytes are charged particles that carry current in solution, the conductance of the solution depends on the concentration of the electrolytes. If you increase the concentration of electrolytes in a solution, the conductance of the solution also increases. In order to measure a current in the solutions, you have to apply a voltage. You will use a 9-volt (V) battery to supply the voltage.

Conductance is measured in units, called siemens, and has the symbol G. The symbol for current is I, and it is measured in amperes (amp). Voltage, V, is measured in volts. Calculating the conductance is easy—it is the current divided by the voltage, as shown below in Equation 1 below.

Equation 1.

• G is conductance, measured in siemens.
• I is current, measured in amperes.
• V is the voltage, measured in volts.

Terms and Concepts

• Electrolyte
• Dissociate
• Ion
• Solution
• Conduct electricity
• Electricity
• Homeostatic mechanism
• Multimeter
• Voltage
• Volts (V)
• Current
• Amps, microamps, milliamps
• Resistance
• Ohms
• Ammeter
• Conductance
• Proportional
• Siemens
• Direct current
• Alternating current
• Open circuit
• Electrolysis
• Dilute

Questions

• What are the amounts of sodium, potassium, and carbohydrates in one serving (8 ounces [oz.]) of orange juice? How does this compare with sports drinks?
• What do electrolytes do in your body?

Bibliography

• Medline Plus Medical Encyclopedia Staff. (2012). Electrolytes. Retrieved October 16, 2012 from http://www.nlm.nih.gov/medlineplus/ency/article/002350.htm
• How Stuff Works. (2008). What are electrolytes? Retrieved August 20, 2008, from http://www.howstuffworks.com/question565.htm

Materials and Equipment

Supplies for this project are available in one convenient kit from the Science Buddies Store

• Copper wire, bare, 24-gauge (around 1.5 meters [5 feet]); available at most hardware stores
• Wire cutter
• Ruler
• Pen cap from a disposable ballpoint pen; make sure the cap does not have a metal clip.
  • Any plastic tube, plastic cylinder, or rubber cylinder approximately 2.5 centimeters (1 inch) long and up to 1 cm wide may be substituted.
• 9 V battery
• 9 V battery clip
• Wires with alligator clips for making connections, should have clips on both ends, and be about 15 cm (6 inches) long (2)
• Binder clip
• Small plastic, glass, or ceramic bowls, not metal (8)
• Masking tape
• Permanent marker
• Sports drink(s) of your choice, room temperature
  • Science Buddies Kit: The kit includes distilled water and sports drink powder. To make the sports drink, mix 1/4 of the drink mix with 1/2 cup (120 mL) of distilled water.
• Orange juice of your choice, room temperature
• Distilled water (dH₂O), room temperature; available at most grocery stores
• Tap water, room temperature
• Measuring cup or beaker, 1/2-cup capacity
• A digital multimeter, for example, this one from Amazon.com
  • Note: The multimeter has various sensitivity settings. Some multimeters automatically change sensitivity, but most inexpensive ones have a dial that sets the sensitivity. Typical multimeters have a range of settings from 200 microamps up to 200 milliamps. This is a thousand-fold range. The 200-microamp setting is good for measuring from 0–200 microamps, but it will not work for higher currents. The 200-milliamp setting is good for 20–200 milliamp currents, but is inaccurate for low currents (microamps). For this project, you will most likely use the 200 microamp setting for distilled water and the 200 milliamp setting for the tap water, sports drink, and orange juice.
• Paper towels
• Lab notebook

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Experimental Procedure

Making a Simple Conductance Sensor

1. Using the wire cutter, cut two pieces of copper wire, each about 15 centimeters (cm) (roughly 6 inches) long.
2. Make a conductance sensor like the one shown in Figure 1 below:
   1. Wrap one piece of wire around the pen cap near one end a few times, leaving a 5 cm (2 inch) tail of wire.
      1. Wrap the wire very tightly around the plastic pen cap. If the wires on the conductance sensor move while you are taking measurements, your measurements may be inaccurate. To keep the wires from moving, try attaching the short end of the wire to the longer end by twisting the two together or use a very small drop of super glue to hold the wires in place.
   2. Wrap the second piece of wire around the other end of the pen cap a few times, leaving a 5 cm (2 inch) tail of wire. There should be no contact between the wires, and they should be wrapped tightly enough that they will not slide off the tube.
      1. Caution: Make sure the two wires do not touch. The conductance sensor will not work if the wires touch, and touching wires will blow the fuse in your multimeter.

Figure 1. The conductance sensor consists of a non-conducting core (in this case the core is a plastic pen cap but other plastic or rubber cylinders would work) with copper wire wrapped around the ends. The ions in the solution complete the circuit, enabling current to flow between the copper wires.

Making a Conductance Measuring Circuit

1. Start assembling the conductance measuring circuit by attaching the battery clip to the 9 V battery.
   1. A schematic diagram of the main components of the circuit can be seen in Figure 2 below. Figure 3 below also provides a detailed picture of the entire circuit. Refer to Figures 2 and 3 as you assemble your circuit.

Figure 2. This diagram schematically shows how the conductance measuring circuit should be built. Use alligator clips to connect the multimeter, battery, and conductance sensor. Make sure to connect the positive (+) terminal of the battery with the positive (+) terminal of the multimeter.

Figure 3. This photo shows an example of the completed conductance measuring circuit. Alligator clips are best for connecting the wires, but in a pinch (as shown above with the binder clip) other clips will do.

2. Plug the multimeter test leads into the multimeter.
   1. Science Buddies Kit: For the multimeter in the kit, the black (negative) multimeter probe goes in the lowest of the three holes (the hole labeled "COM") on the bottom right of the multimeter. The red (positive) multimeter probe goes in the middle of the three holes (the hole labeled VOmA). See Figure 3 above.
   2. If you are not using the Science Buddies Kit, consult the manual that came with your multimeter to see which jack should have the positive versus negative probe.
   3. Tip: Make sure the multimeter probes are plugged into the correct jacks, or your experiment will not work.
3. Use one of the pairs of alligator clips to connect the positive (red) wire of the 9 V battery clip to the positive (red) multimeter probe. To do this, clip one of the alligator clips to the positive (red) wire of the 9 V battery clip, and clip the other end of the pair of alligator clips to the metal part of the positive (red) multimeter probe.
   1. In Figure 3 above, the red pair of alligator clips makes these connections. Neither the color nor the actual use of alligator clips is crucial, as long as you make the same connections.
   2. Make sure to clip the alligator clips to the metal part of both the multimeter probe and 9 V battery clip. The circuit will not work if the alligator clips are not connected to the metal parts of the probe and clips leads because the circuit will not be complete.
4. Using the second pair of alligator clips, attach one of the copper wire tails of the conductance sensor to the negative (black) probe of the multimeter. You can use either tail of the sensor. To do this, clip one of the alligator clips to one of the wire tails of the conductance sensor, and clip the other end of the pair of alligator clips to the metal part of the negative (black) multimeter probe.
   1. In Figure 3 above, the black pair of alligator clips makes these connections. You do not have to use a black pair of alligator clips, but you should make the same connections.
5. Use the binder clip to clip the metal end of the black lead from the 9 V battery clip to the other wire tail of the conductance sensor.
6. Double-check your connections to make sure they match those in Figure 3 above. The colors of the alligator clips are not important, but the order of the connections is: the red probe of the multimeter should be connected to the red lead from the battery clip, the black lead of the battery clip should connect to one of the wire tails of the conductance sensor, and the other wire tail of the conductance sensor should connect to the black multimeter probe.
   1. Note that this is an open circuit because of the gap between the wires wrapped around the non-conducting tube. You will use the electrolytes in the solutions to close the circuit. The amount of current that flows is proportional to the electrolyte concentration.

Setting Up Your Test Solutions

1. Clean the eight small bowls with warm soapy water, rinse thoroughly, and dry them right away with a clean dry cloth or paper towel. This will remove ions in the tap water. If you want to be extra careful, rinse the bowls with distilled water before drying.
2. Put masking tape on all eight bowls.
   1. Label four bowls with the following labels: Distilled Water, Tap Water, Sports Drink, and Orange Juice.
      1. Science Buddies Kit: it includes sports drink powder. To make the sports drink, mix 1/4 of the drink mix with 1/2 cup (120 mL) of distilled water.
   2. Label one bowl Tap Water Rinse.
   3. Label the final three bowls as follows: dH₂O Rinse 1, dH₂O Rinse 2, and dH₂O Rinse 3. Use these bowls to rinse the conductance sensor between uses.
3. Pour 1/2 cup (120 mL) of each liquid into the appropriately labeled bowl. All of the solutions should be at room temperature.

Measuring the Conductance

1. Turn the multimeter to read DCA (direct current). Make sure it is reading direct current (DCA) and not alternating current (see the instructions for your multimeter).
   1. For measuring distilled water, the meter should be set to DCA 200 microamps (200µ). For measuring the tap water, orange juice, and sports drink samples, the meter should be set to a higher setting, like DCA 200 milliamps (200m).
      1. This page explains how to use a multimeter: Electronics Primer: Using a Multimeter
      2. The FAQ for this Project Idea has more details and troubleshooting advice about using the multimeter for this particular project.
2. Place the conductance sensor in the distilled water. Make sure the sensor tube is completely immersed. See Figure 4 below for an example of what the completed setup should look like, with the conductance sensor immersed in the liquid.

Figure 4. The completed circuit, with the conductance sensor immersed in a bowl of tap water, is shown here. The current (I) is the readout on the multimeter. In this case, the current is 0.4 mA and the voltage, from the battery, is constant at 9 V. The conductance can be calculated using these measurements and Equation 1.

3. Read the current on the multimeter. If you are not using an auto- ranging multimeter, move the dial to its highest sensitivity (e.g., 200µ).
   1. Always make your readings quickly and remove the conductance sensor from the solutions immediately. Over time, the copper wires will start to dissolve in the solutions, skewing your results. In addition, electrolysis may take place, forming tiny bubbles on your conductance sensor that can interfere with your data.
4. Record the current (the readings from your multimeter) in your lab notebook in a data table. Make sure to record the units you are using (either microamps or milliamps) so that you can plug it in to the equation correctly later.
5. No need to rinse this time because you used distilled water.
6. Now place the conductance sensor in the tap water.
7. Record the current. Again, make sure you are using the proper sensitivity scale. You will need to use a lower sensitivity for tap water (e.g., 200m) than you used for distilled water.
8. Tap the sensor on a paper towel to remove drops of tap water. Then rinse the sensor in distilled water, dipping it briefly in each of the three distilled water rinse bowls.
9. Place the sensor in the sports drink and measure the current. Record the current in your lab notebook.
10. Tap the sensor dry, and then dip the sensor in tap water, then in the three bowls of distilled water.
11. Place the sensor in the orange juice and measure the current. Record the current in your lab notebook.
12. Rinse the sensor in the tap water and then in all three distilled water bowls.
13. Repeat steps 1-12 in the "Measuring the Conductance" section two more times to obtain a total of three measurements for each liquid. Record all data and measurements in the data table in your lab notebook.
14. Average your results across the three measurements for each liquid.
15. Convert microamps to amps by dividing by 1,000,000. Convert milliamps to amps by dividing by 1,000.
16. Calculate the conductance for each liquid by using Equation 1, shown in the Introduction.
    1. The current (I) for each liquid is the average amps that you calculated.
    2. Since the voltage was always from your 9 V battery, you can use 9 V as the voltage (V) in your calculations. In reality, the voltage is likely to be slightly less than 9 V due to internal resistance of the battery. But this change is quite small and nearly constant across the experiment. Because it is so small, you do not need to take it into account. If you have a second multimeter though you can adapt the circuit to monitor both current and voltage across the battery.
17. Which liquid has the highest conductance, meaning the most electrolytes?

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Variations

• Try other sports drinks and juices.
  1. What is the conductance of fresh-squeezed orange juice?
  2. What about the conductance of lemonade?
• Try making your own sports drink, starting with orange juice. If the carbohydrates in the orange juice are higher than they are in the sports drink, dilute the juice with distilled water so that the carbohydrates are about the same as they are in the sports drink. How does the conductance of the diluted juice compare to that of the sports drink?
• Make a conductance sensor using a microphone jack.
• Standardize your readings, using tap water as a reference. Divide all of the current measurements for each trial by the current you measured for the tap water. Tap water will have a conductance of 1.0. The fruit juice and sports drinks will then have conductances that are multiples of the tap water's conductance.

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Volga said:
2013-03-24 19:20:57

What was the most important thing you learned?
The most important thing I learned would probably be, Gatorade has the highest ampage, and try to include something other than orange juice and a sports drink. ( Fruit Punch? )

What problems did you encounter?
Some problems encountered would be, the displayed pictures of setting up the wires up to the digital multimeter did not work. It was the opposite.

Can you suggest any improvements or ideas?
Any improvements? Well, I would just say, if your digital multimeter is not functioning correctly, try switching the cables.

Overall, how would you rate the quality of this project?
Excellent

What is your enthusiasm for science after doing your project?
Very high

Compared to a typical science class, please tell us how much you learned doing this project.
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JeffreyMilen said:
2013-01-30 18:17:46

What was the most important thing you learned?
none

What problems did you encounter?
multi meter was malfunctioning, and fuse had to be bypassed (covered with aluminum foil)

Can you suggest any improvements or ideas?
more drinks tested

Overall, how would you rate the quality of this project?
Very Good

What is your enthusiasm for science after doing your project?
Moderate

Compared to a typical science class, please tell us how much you learned doing this project.
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angelride101 said:
2012-12-17 18:44:29

What was the most important thing you learned?
Which drinks contained the most electrolytes

What problems did you encounter?
none

Can you suggest any improvements or ideas?
none

Overall, how would you rate the quality of this project?
Very Good

What is your enthusiasm for science after doing your project?
High

Compared to a typical science class, please tell us how much you learned doing this project.
More

Do you agree?

1

0

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bunnny126 said:
2012-11-09 17:32:44

What was the most important thing you learned?
That electrolytes are essential to our health

What problems did you encounter?
None

Can you suggest any improvements or ideas?
I added another drink to project. I added coconut water, beacause it saud that it had more electrolytes than the avereage sports drink. Maybe you could add another drink.

Overall, how would you rate the quality of this project?
Very Good

What is your enthusiasm for science after doing your project?
High

Compared to a typical science class, please tell us how much you learned doing this project.
More

Do you agree?

1

0

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Frequently Asked Questions (FAQ)

A: For this project, the black multimeter probe should be inserted into the hole on the bottom of the multimeter labeled "COM" or "-" and the red multimeter probe should be inserted into the hole directly above it labeled "'V Ω mA" or "'V Ω LOGIC" or something similar. To measure the current of your samples, make sure the multimeter dial is set to the DCA area (which stands for DC Amps), not DCV (which stands for DC Volts). Set it to the 200 milliamps setting to measure your samples (except for measuring the distilled water, when it should be set to the 200 microamps setting). You may also want to refer to the multimeter's instructions for more information on how to take readings. If you purchased a Science Buddies kit, then you can look at Figure 1 below to see how to set up your multimeter.

Figure 1. Proper setup for the multimeter included in the Science Buddies kit. Other multimeters may be similar. The black multimeter probe goes in the lowest of the three holes (the hole labeled "COM") on the bottom right of the multimeter. The red multimeter probe goes in the middle of the three holes (the hole labeled VΩmA). For measuring your tap water, orange juice, and sports drink samples the meter should be set to DCA 200m, which means the meter is measuring current in the 200 milliamp range. For measuring distilled water, the meter should be set to DCA 200μ, which means the meter is measuring current the 200 microamp range.

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