Why is my salt solution not lighting the bulb?

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Discussion Overview

The discussion revolves around the failure of a saltwater solution to light a bulb connected to a 9-volt battery, exploring the conductivity of various solutions and the factors affecting the circuit's performance. The scope includes experimental observations, potential explanations, and troubleshooting steps related to electrical conductivity in solutions.

Discussion Character

  • Exploratory, Experimental/applied, Debate/contested

Main Points Raised

  • One participant describes their setup with a 9-volt battery and Christmas lights, noting that the bulb lights outside the solution but not in it.
  • Multiple solutions with varying concentrations, including calcium chloride and NaCl, were tested without success, although conductivity was observed with a tester.
  • Another participant suggests measuring the current flowing through the circuit, proposing that it may be too low for the bulb to light.
  • A participant recalls that the bulb lit briefly in a 3 molar HCl solution, indicating that the current may be present but insufficient in other solutions.
  • One participant emphasizes that ion identity matters, suggesting that H+ ions are particularly effective for conductivity.
  • Another participant recommends increasing the electrode surface area and reducing the distance between electrodes to improve conductivity.
  • Concerns are raised about the salt-to-water ratio potentially being incorrect.
  • One participant expresses uncertainty, stating they are just guessing.

Areas of Agreement / Disagreement

Participants express various hypotheses regarding the conductivity of the solutions and the factors affecting the circuit, but there is no consensus on the exact cause of the bulb not lighting. Multiple competing views and suggestions remain unresolved.

Contextual Notes

Participants mention the importance of ion identity and concentration, as well as the physical setup of the electrodes, but do not resolve the implications of these factors on the experiment's outcome.

Who May Find This Useful

Individuals interested in experimental physics, electrical conductivity, and troubleshooting electrical circuits may find this discussion relevant.

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So I have a typical 9volt battery attached to a Christmas light and am attempting to demonstrate the typical "saltwater can conduct electricity" gimmick by showing that the bulb lights when completing the circuit in the solution. I'm racking my brain though and can't figure out why the bulb won't light!

Some details:
-The bulb does of course light when the wires are connected outside of solution.
-I've tried multiple solutions with multiple concentrations (calcium chloride, acids, NaCl, etc) with no luck.
-However, a conductivity tester also attached to a 9volt battery does show some conductivity in the water.
-The test battery with the Christmas light does hydrolyze the water (produce bubbles).
-After attempting the test setup in the solution, I stuck the wires together for a bit outside of the solution. When I did this, one of the wires began to blacken just a tiny little bit. I then stuck the wires back in the solution and a slight yellow precipitate formed. This makes me think there is some coating on the wire (though I don't see why there would be) or that there is some electroplating going on (though this is never really noted in other setups of this experiment I found on the internet). The yellow precipitate I noticed in the NaCl solution.
-The Christmas lights was just the typical LED green chains you normally see. One of the lights was taken off just by cutting the wires on both ends of a light. Simple simple.

Any ideas as to what's going on?
 
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Have you measured what is the current flowing through the circuit? My bet is that it is just too low for the light.
 
That may well be it. The light is NOT an LED like I originally posted on second thought (or at least that's not a safe presumption; I don't know how to truly tell the difference visually). But no I didn't measure the current numerically.

Another detail I forgot, the bulb did light up BRIEFLY in an HCL solution. That does make me think the current's somewhat there just not enough for the bulb.
 
I just remember that the HCl solution that did work briefly was 3 molar. To get that same concentration in table salt, we would have had to add much more than we did. It seems like there just no being enough juice to get through is a reasonable resolution to this unless anyone seems something missing.
 
It is not only about concetration, also about ion identity - H+ are are the best.

Try to increase electrode surface, and try to keep electrodes as close to each other as possible. Conductivity 101.
 
also if your doing salt to water your raitio may be off
 
just guessing
 

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