Re: How can you measure electrolytes in sport drinks or other drinks?

Hello, Dave.  Welcome to the Mad Scientist Organization!

Your battery tester measures electrical current. The wires act as 
conductors, and your solutions contain electrolytes.  These are substances 
that conduct electricity.  The most important electrolytes are made up of 
salts, acids and bases. You've noted that the water contained more 
electrolytes than your pineapple juice did.  To see how battery testers 
work, go to www.howstuffworks.com and search 'battery testers'. 

A classic method to test solutions is one in which a conducting apparatus 
is used.  A conducting apparatus can be constructed by using a 9 volt 
battery, a small appliance light bulb, 3 pieces of insulated copper wire, 
and 2 electrodes, say metal plates.  The connections are as follows:  one 
electrode connects directly to a battery through a wire, the other 
electrode connects by a wire to a light bulb, which in turn connects by 
wire to the other side of the battery.  For an electrical current to flow 
from the battery, there must be a complete circuit which allows the 
current to flow from the positive pole of the battery, through the 
circuit, to the negative pole of the battery.  Your solutions must also be 
able to conduct electricity. 
 
When the electrodes are placed in a strong electrolyte solution, the bulb 
glows brightly, likewise, a weak solution makes the bulb glow dimly.  It 
won't glow at all in a solution of nonelectrolytes.  This experiment 
allows you to visualize the conductivity of various substances.  

The explanation for this is, that when the current passes into the 
solution, the electrolytes dissociate, (breaks up), into ions.  The more 
free ions available, the stronger the current and the better it conducts 
electricity.  It turns out that salts are strong electrolytes, while sugar 
solutions are nonelectrolytes.  Pineapple juice is very high in sugar, and 
is consequently a weaker electrolytic solution. Tap water naturally 
contains some minerals, with no sugar, and therefore produces a stronger 
electrical flow.


Many other fun and interesting experiments such as this, or others 
concerning electrochemistry can be found at:  www.funsci.com
Click on 'Experiments in Electrochemistry'.  Here you will learn more 
about the conductivity apparatus, and its applications.  

Finally, it's important to clarify that it isn't electrolytes that 
provides us with energy, or any extra energy for that matter.  Mineral 
water is no better than distilled water in terms of providing energy.  

Energy is found in many forms, and what you're witnessing is electrical 
energy.  The unit of energy that fuels our body comes from glucose,  
derived from the breakdown of food.  Therefore, pineapple juice will 
supply us with energy, water will not! 
 
Sports drinks can either be 'energy drinks', which are high in sugars, 
+/or drinks containing minerals.  The latter are designed to replenish 
salts lost during strenuous excercise.  Red Bull is popular because it 
contains caffeine, (80 mg. per drink), but you often can get more caffeine 
from a cup of coffee.

Unless you're an athlete, or involved in heavy excercise, or endurance 
activities, save your money, eat a proper diet and drink plenty of water.  
You'll get all the energy you need.

Hope that helps,

Peter Bosani

References: Chemistry Made Simple - Fred C. Hess - Doubleday  1984.
            The Sciences - M. Beazley Encyclopedia - 1980