Name: ____________________________________________________ Date: __________________________
Chemistry Lab: Ionic Mixtures
Introduction:
Gatorade has built its business around “electrolytes”. At a chemical level, electrolytes are substances that
form ions when dissolved in water. Since ions can conduct electricity, electrolytes play a vital role in
maintaining muscle function, hydration levels, and acidity in the body. Table salt (NaCl) is an example of an
electrolyte- when added to water it will form sodium and chloride ions.
Pre-Lab (10 pts.):
1) What is the charge on each ion after NaCl separates in water?
a) Write the cation and its charge:
b) Write the anion and its charge:
2) Take a clear picture of the 2 nails on your tray and save it for later.
Scenario:
You are a marketing executive for a new sports drink company and are trying to create its first product, which
is formulated to quickly replace electrolytes lost by athletes while exercising. Your research and development
team has presented you with 3 proprietary substances to include in the drink, but they did not label them
properly. You must now determine which substance is the strongest electrolyte.
Hypothesis (5 pts.):
Predict a relationship between the amount of electrolyte added to a solution and its electrical conductivity:
Materials:
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250 mL beaker
3 unknown substances- triangle, square, circle
glass stir rod
metal scoopula
filter/weigh paper
triple beam balance (scale)
ammeter
battery
3 wires with clamps
electrodes (nails)
Procedure (50 pts.):
1) Add 200 mL of water to the 250 mL beaker
2) Set up a circuit (see front desk for model)
3) Measure the electric current by placing both electrodes into the water (make sure they are not touching).
Record the value on the ammeter in Table 1 below, and then remove the electrodes from the water.
4) Choose an unknown substance and draw the shape on the beaker in the box above Table 1.
5) Using a metal scoopula and a coffee filter as weigh paper, measure out 1 gram of the substance on the
scale, and then add it to the water beaker. Stir the solution using a glass stir rod until the substance has
dissolved.
6) Place the electrodes into the solution again, connect the battery, and record the electric current (measured
in milliamps) in Table 1. Record your observations in the ‘Experimental observations’ section below.
7) Repeat steps 5 and 6 until you reach 10 total grams of material added. Continue to record your data in
Table 1*.
*IMPORTANT: If you reach 5 total grams of solid added but still register no current on the ammeter, stop and
rinse out the beaker, then move on to the next substance.
Experimental observations (hint: look at the submerged electrodes when electricity is applied):
a)
b)
c)
Table 1
Unknown
Mass of solid added (grams)
0
1
2
3
4
5
6
7
8
9
10
Current (milliamps)
8) Once you have added 10 total grams of solid (or if at 5 grams you recorded no current), pour the solution
down the drain and rinse the beaker thoroughly.
9) Refill 200 mL of fresh water to the beaker and measure the electric current using the electrodes. Record the
current in Table 2 below.
10) Repeat steps 4-9 with the other two unknown substances. Record your data in Tables 2 and 3 below.
Table 2
Unknown
Mass of solid added (grams)
0
1
2
3
4
5
6
7
8
9
10
Current (milliamps)
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Table 3
Unknown
Mass of solid added (grams)
0
1
2
3
4
5
6
7
8
9
10
Current (milliamps)
Analysis (35 pts.)
1) On a sheet of graph paper, create a combined line graph of the mass of solid added vs. milliamps for all 3
unknown substances. Label each line with its shape.
a) Based on your graphs, rank the shapes from lowest electrical conductivity to highest electrical
conductivity:
b) Which substance is the strongest electrolyte?
c) Which substance is not an electrolyte?
2) Based on your experimental observations, what did you notice around the electrodes when they were
submerged in the solution? Did you observe a change in the color of your electrodes (reference your picture)?
3) Research: What is electroplating? How does electroplating apply to this experiment?
4) “Once is luck, twice is a coincidence, three times is a pattern.”
How does this quote apply to taking experimental measurements?
5) Gatorade uses Unknown Substance O as its main ingredient. Which substance (∆, ꓳ, □) would you use as
the main ingredient for your sports drink?