# Determining the theoretical mass of gas produced through the process of electrolysis

I have a question that has been stumping me for quite some time. I wish to calculate the mass of gas that is produced from varying concentrations of salt (NaCl) through the process of electrolysis. I know the calculation for finding the moles of gas produced.

n = Q/(Fz)

The problem is that I do not have the number of coulombs. Therefore using the equation:

Q = It

I am able to find the coulombs but now I do not know how many amps. I know that amps can be found by dividing volts by resistance:

I = V/R

Now I need to know my resistance. I have found on the Internet that the conductivity can be determined by multiplying the molar conductivity by the concentration but I'm not 100% sure.

My mass of salt used was table salt (NaCl) 20g 40g 60g 80g 100g

My volume of water was 255mL

The battery I used was 9v energizer(alkaline)

I placed the batteries directly into the solutions

• But I need to find the resistance – Andrew Jan 24 '18 at 3:19
• Without knowing conductivity – Andrew Jan 24 '18 at 3:20
• sciencing.com/… – Andrew Jan 24 '18 at 3:21
• This is the site where I found the calculation of conductivity from varying concentrations – Andrew Jan 24 '18 at 3:22

Finding the resistance or the conductivity of an electrolysis cell is not that easy when doing it with pure math.

Why don't you just apply a voltage to your cell and measure the current?

R = U / I (resistance = voltage / current)

The resistance of your cell depends on many factors:

a) Cell design

• bottlenacks
• distance of electrodes
• number of electrodes
• material of the electrodes
• surface area of the electrodes

b) Electrolyth

• What sort of salt you are using
• The ion concentration of the dissolved salt

c) Temperature

• the temperature changes the resistance of the electrolyth a lot.

You see, that things are not that easy and there is no simple formula, at least not that I know of, to calculate the resistance of an electrolysis cell.