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5D30.10 - Conduction of Salt Water

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​5D30.10 - Conduction of Salt Water

Preview
SelectSelected
Title5D30.10 - Conduction of Salt Water
Objective

Demonstrate that pure water is not a conductor, but an ionic solution is.​

StatusAvailable
Assembly Instructions

​Pull out the glass vessel with two long electrodes separated by a piece of plexiglas mounted inside of the vessel.  Connect banana cables to the electrodes and connect those in series with the 110-VAC power switch (4-way on/off switch with breakouts).  Plug in a 25-W bulb into one of the plugs of the 110-VAC power switch.  Provide 300 mL of de-ionized/distilled water and salt.  Make sure the insulated banana cable is available for shorting out the electrodes and a long plastic rod is used to stir the salt into the water.  Must have a danger sign.

Check that when you short out the electrodes, the 25-W bulb lights up.  Make sure the vessel is clean.

Setup Time12
Operation Time5
Preview Time5
Operation Instructions

First, turn on the 110-VAC power switch and observe nothing happens.  Use the insulated banana cable to short out the long electrodes to show that the 25-W bulb will light when the circuit is completed.  Then fill the glass vessel with the provided de-ionized/distilled water. The two long electrodes are submerged in the water. The bulb will not light (make sure the vessel is clean). When some salt is added, the bulb will begin to light, indicating that salt dissolved in water can act as a conductor.  (Optional in Weiser Hall- thoroughly rinse out the glass chamber after disconnecting it from the power switch to remove all of the salt water.  Then fill vessel with classroom water, re-insert into circuit and show how that will work too, tap water is not just water.)

ExportableNo
Demo on DimeNo
PIRA 200No
Export Instructions (if different)
HazardsExposed High Voltage - AC Current
Analysis/Information

​Pure Water - water that has been purified through mechanical filtration or processed to remove imuprities (distillation, deionization, demineralization, etc).  Impurities that are removed include inorganic ions, organic compounds, bacteria, endotoxins/nucleases, particulates, gases.

Pure water does not contain any ions, therefore it is not electrically conductive. 

If an electrolyte, a substance that produces an electriclaly conducting solution when dissolved in a polar solvant, is added to water then ions are formed and electrical conduction can occur.  In this case, we have added table salt NaCl to the pure water, which dissolves into Na+ and Cl- evenly throughout the solution.  The water is electrically neutral, but if an electrical potential is applied to such a solution, a current is formed.

Category5 Electricity and Magnetism
Subcategory5D - Resistance
Keywordsmiscellaneous, ionic solution, conductor
Construction Information
Properly insulated banana cables are necessary in order to short out the live electrodes as it is live 120-VAC to keep hands safe. 
 
Equipment TitleUse SHIFT+ENTER to open the menu (new window).
  
QuantityUse SHIFT+ENTER to open the menu (new window).
  
water - de-ionized
salt
AC power switch - four outlets, with volts/amps breakout
1
glass vessel with two (2) long electrodes and plastic stir rod
1
banana cable
2
light bulb - 25W
1
insulated banana cable
1
danger sign
1