Student Question

# Write a chemical equation that shows that hydrogen fluoride dissolving in water and write a sentence  to explain why the solution will conduct electricity?

Hydrogen fluoride reacts with water to form an acidic solution. The chemical equation of hydrogen fluoride reacting with water is:

`HF + H_2O harr H_3O^+ + F^-`

From the equation it can be seen that the addition of hydrogen fluoride in water leads to the formation of a positive ion `H_3O^+` and `F^-` . These charged ions help in the conduction of electricity with the positively charged ions moving towards the cathode and the negatively charged ions moving towards the anode. At the cathode, the ion would absorb an electron forming water and hydrogen and at the anode the ion would give up an electron forming fluorine gas. The water solution would continue to conduct electricity forming fluorine and water in the process till there is none of the electrolyte left.

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On its own, or pure water (H20) does not conduct electricity very well. That said however, when certain substances as in this case, Hydrogen Fluoride-are dissolved in water, the solution does conduct electricity.

HF + H2O → H3O+ F –   or   HF (aq) + H2O → H3O+ (aq) + F – (aq)

Hope this helps!

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Write a chemical eqution that shows that hydrogen sulphide dissolving in water and write a sentence to explain why the solution will conduct electricity?

Hydrogen sulfide (H2S) is slightly soluble in water and acts as a weak acid.  As a weak acid, it dissociates initially into the hydrosulfide ion, HS- (pKa=6.9), and then the sulfide ion, S2- (pKa=11.96).  The presence of the hydronium ion, H3O+ is also present.  The presence of all these intermediary ions is sufficient to conduct the flow of electrical current through the solution.

The formulas would be as follows:

H2S  + H2O  --->  HS-   +  H3O+

HS-  +  H2O  --->   S--   +   H3O+

The solution is initially clear, but clouds up over time due to the slow reaction of hydrogen sulfide with the oxygen in the water.  Over time, elemental sulfur is precipitated out of the solution.

Hydrogen sulfide is a gas at room temperature and has a very disagreeable odor, similar to that of sewer gas or rotten eggs.  When combined with elemental oxygen at high temperatures, it can produce elemental sulfur and water, known as the Clauss reaction.

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Write a chemical equation that shows hydrogen fluoride dissolving in water and write a sentence to explain why the solution will conduct electricity

The equation for the dissolution of hydrogen fluoride in water can be written as:

`HF + H_2O -> H_3O^+ + F-`

We can also write the equation omitting the water in the equation  to show that HF can be ionized in the solution. We can write is as:

`HF -> H^+ + F^-`

The reason why HF can conduct electricity is because it can produce ions in the solution. Ions that are dissociated in the solution are free to move thus can conduct electricity. However, HF is not a strong acid compared to other hydrogen halides such as HCl and HBr.