Question

Protons are attached to a water molecule (making hydronium) in acidic solutions. If a container was split through the middle with a cation-permeable but anion impermeable membrane and, say, HCl was added to one side, what would happen?

I'd assume because of the concentration gradient, osmosis will cause hydronium ions to move to the less concentrated side until equilibrium is reached.

But that would also make charge very uneven on both sides, where one side is highly negatively charged and the other side is very positively charged. So, I am not sure osmosis alone could even lead to this state.

Considering the ions on either side are either electron deficient or have full shells, and have the same charge, I would not expect any gas to come out of solution.

If a negative electric current was applied to one side of the container, and a positive on the other, would that produce gas more efficiently than plain electrolysis? If it depends, then under what conditions?

Or am I wrong, and what will happen to the ions from the acid?

Answer 1

If HCl is added to one side of a container split by a cation-permeable but anion-impermeable membrane, osmosis will occur to equalize the concentration of hydronium ions on both sides. To efficiently produce gas, you can apply an electric current to the container using the process of electrolysis.

Step-by-step explanation:

In this scenario, if HCl is added to one side of a container split by a cation-permeable but anion-impermeable membrane, osmosis will occur to equalize the concentration of hydronium ions (H3O+) on both sides of the membrane. Osmosis is the movement of water from an area of higher concentration to an area of lower concentration.

However, osmosis alone will not result in an equal distribution of charge on both sides, as you observed. To efficiently produce gas, rather than relying on osmosis alone, you can apply a negative electric current to one side of the container and a positive electric current to the other side, which will result in the process of electrolysis.

Electrolysis is the process of using an electric current to drive a non-spontaneous chemical reaction.