LAB 1 - NaCl
How does the amount of electrical current passing through a solution depend on the concentration of salt?
| distilled water (dH2O)
||triple beam balance
| metal scoop
| P1000 micropipet/tips
Lab Instructions (Procedure):
- Make up your salt "stock" solution. Weigh out exactly 5.8 grams (gm) of NaCl and transfer them quantitatively to 100 mL distilled water (dH2O). Dissolve the salt and make sure the solution is thoroughly stirred.
- Add 300 mL dH2O to the electrophoresis chamber. Connect the power supply to the chamber and set
the power supply to 100 volts (V), then check the current on the amp meter - it should
read 0 milliAmps (mA). Record this value in your data table. Turn off the power
- Add 1.0 mL of salt stock
solution (5.8gm/100ml) to the electrophoresis chamber. Rock the chamber to mix the
salt thoroughly. Read the current (mA) with the power supply set at 100V. (Try to get the earliest
reading because the meter will slowly drift upward with time.) Record in data table.
- Continue adding 1.0 mL portions of stock solution to the chamber, each time recording the current with the power supply set at 100 volts until you have collected
5 to 6 readings.
- Dispose of salt solutions in the sink and rinse the chamber and stock solution
- Graph the data from your table.
| volume of
stock solution added
to the chamber
| relative concentration
of stock solution added
to the chamber
- Draw a graph showing how the electric current that goes through the solution depends
on the concentration of the salt solution.
Electric Current vs. Salt Concentration
- Restate your hypothesis.
- State whether your hypothesis was right or wrong.
- Describe evidence from your data section that supports your conclusion.
- Using numbers, describe how the current changes as salt concentration is changed.