Why is electricty conducted through salt water?

In summary, when electricity is passed through salt water, the negative ions (such as chloride ions) are attracted to the positive terminal and move towards it, causing a current. This is because it takes less energy for them to move than to transfer electrons between oppositely charged ions. Additionally, the polar solvent of water provides an environment for the ions to remain ionized. In terms of the anode, the excess electrons of negatively charged ions are attracted to the positive terminal due to the electric field set up by the external battery, causing the ions to lose their electrons.
  • #1
sameeralord
662
3
Ok so when I pass electricty through salt water the negative ions move from highly negative area to positive area causing a current? My question is why do the move? Let's say there was Sodium and Chloride ions in water. Can't the chloride ion give an electron to sodium and make the whole solution deionized, why do they choose to move instead?

Thank you :smile:
 
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  • #2
sameeralord said:
Ok so when I pass electricty through salt water the negative ions move from highly negative area to positive area causing a current? My question is why do the move? Let's say there was Sodium and Chloride ions in water. Can't the chloride ion give an electron to sodium and make the whole solution deionized, why do they choose to move instead?

Thank you :smile:

The simplest reason is that it takes *way* less energy to move ions around than to transfer electrons between oppositely charged ions. This is because many simple ions (like Na+ and Cl-) are stabilized by interactions with water, so they are "happier" (i.e. existing in a lower energy state) as ions than as neutral atoms in water.
 
  • #3
Can't the chloride ion give an electron to sodium and make the whole solution deionized, why do they choose to move instead?
If that happens, it indicates a chemical reaction. For every chemical reaction to happen, it requires appropriate environment i.e. pressure, temperature and other parameters. Now water being a polar solvent doesn't provide chloride ions appropriate environment to transfer their excess electrons to sodium ions. Instead they remain ionized in a polar solvent like water as the water provides that kind of environment to stay them ionized. After being ionized the anion chloride ions are attracted to the anode connected to the +ve terminal of the battery and cation sodium ions are attracted to the cathode connected to the -ve terminal of the external battery. Then each of them take and leave electrons in the cathode and anode.
 
  • #4
Thanks for the great replies :smile: I have just one mini question left.

Then each of them take and leave electrons in the cathode and anode.

I can understand how reduction reaction can occur in the catode because they supply electrons at that end, but in the anode what make the ion lose its electrons thanks.
 
  • #5
but in the anode what make the ion lose its electrons thanks
The event of losing electrons in anode can be interpreted in terms of the electric field set up by the external battery. As the battery exerts an electric force on the negatively charged chloride ion, its excess electron located loosely in its out most shell is attracted by the electric force . The electric force F= qE accelerates the excess electron of chloride ion to the direction of +ve terminal. Hence, chloride ion leaves electrons in anode.
 

1. Why does salt water conduct electricity?

Salt water conducts electricity because it contains charged particles called ions. When salt, or sodium chloride, is dissolved in water, it breaks down into positively charged sodium ions and negatively charged chloride ions. These free ions are able to move within the water, allowing for the flow of electric current.

2. How does the concentration of salt affect the conductivity of water?

The higher the concentration of salt in water, the more ions there are present to conduct electricity. Therefore, increasing the concentration of salt will increase the conductivity of the water. However, there is a limit to this effect, as extremely high concentrations of salt can actually decrease the conductivity.

3. Can any type of salt be used to conduct electricity through water?

Yes, any type of salt can be used to conduct electricity through water. However, the most commonly used salt is sodium chloride, as it is readily available and highly soluble in water. Other salts, such as potassium chloride or magnesium chloride, can also be used but may have different effects on the conductivity due to their different ion sizes and charges.

4. How does temperature affect the conductivity of salt water?

Temperature does have an effect on the conductivity of salt water. As temperature increases, the molecules in water become more energetic and can break apart the ions more easily, increasing the conductivity. However, extremely high temperatures can also cause the water to evaporate, reducing the amount of ions available to conduct electricity.

5. Why is salt water a better conductor than plain water?

Salt water is a better conductor than plain water because it contains free ions that can move and carry electric charge. In plain water, there are fewer ions available to conduct electricity, making it a poorer conductor. Additionally, the presence of ions in salt water allows for the formation of an electrical circuit, which is necessary for the flow of electricity.

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