what makes the difference in voltage output of a voltaic cell, if the chemical in the salt bridge is changed (KCl, KNO3, NaCl, NaNO3)?

Question

The chemical is changed with KCl, KNO3, NaCl, NaNO3. So it has been found that the KCl has the most voltage output than the other chemicals. So why is that?

Answer 1

It shouldn't matter what you put in the salt bridge so long as it doesn't react with any of the chemicals used in the voltaic cell.  For example, you wouldn't want to use a chloride salt (NaCl or KCl) if you are using Ag as an electrode with AgNO3 in solution, because you would precipitate AgCl.  Other than that, all of the ingredients listed for the salt bridge should work equally well.