# Resistivity of pure water vs salt water for electrolysis

OK so I have a group project. Were "building" an ammonia plant. Part of the plan is to gather the $\ce{H2}$ we need from the splitting of pure water. We've been told $1000\ \mathrm{kg}$ of $\ce{NH3}$ must be produced an hour. One of the problems asks for the voltage and current needed to split pure water to make enough $\ce{H2}$. I can do the half reaction, that's easy $1.22\ \mathrm V$. But I've done this loads of times with kids and a $9\ \mathrm V$. I know that adding a little salt speeds up hydrogen gas production. Does the $1.22\ \mathrm V$. assume that its pure water and I don't have to worry about the resistivity?

• for 1000kg/hr I suggest you do not use electricity. The amount of wire need to sustain the needed current will be outrageous. – A.K. Mar 6 '16 at 4:41
• The salt just allows for the current to flow. The only reason it worked with "pure" water is because of the small amount of salts that were actually present in the water, or dissolved from the sides of the glassware, etc. – airhuff Feb 7 '17 at 5:27
• I hope you are just designing something and not trying to build it: that is quite a large task for this volume of ammonia! – matt_black Feb 7 '17 at 11:04