0
$\begingroup$

I'm in a General Chemistry course in college. We have laboratory, and then we are supposed to make a report on what we did, etc.

I'm not entirely sure what the last laboratory was about, but it was called Salt and Water Electrolysis

To sum up the procedures -two general procedures-, here's what we did:

1st Procedure:

  • We prepared 50 mL of a $\ce{NaCl(aq)}$ solution at 0.1 M (molarity) in a 100 mL beaker

  • We made a DC (direct current) circuit at 5V and 700 mA, with graphite electrodes

  • We turned the circuit on for roughly 20 minutes

  • We employed a magnetic stirrer to stir the solution

  • We added 3 drops of Phenolphthalein in the solution, and took notes of the phenomena. (I guess it kinda turned pink)

And that was that for the 1st procedure.

2nd procedure:

  • We measured the solution's pH with a pH meter

  • We measured roughly 15 mL of $\ce{HCl}$ (Hydrochloric Acid) at 0.5 M with a test tube

  • We poured the solution of $\ce{HCl}$ in a 25 mL burette.

  • We prepared the titration equipment

  • We were supposed to add the $\ce{HCl}$ (drop by drop) to the $\ce{NaCl}$ solution and at the same time be measuring the pH until it got to 7

And that was that for the second procedure.

Of course we kind of messed up, as we overshot the end point. The excess $\ce{HCl}$ brought it's pH to 3 point something.

The $\ce{NaCl}$ solution lost its pink color, and then turned yellowish.

So.. I guess I am asking for references to the equipment involved -I kind of have references for the pH and the properties involved, still, if you know of some references, let me know!-, I've looked for electrolysis processes in books but don't find any. Or they're too technical. Also, haven't found titration procedures in books.

Can you help me out, just so I can finish my report?

$\endgroup$
  • $\begingroup$ Welcome to Chemistry.SE! I wish to politely draw your attention to this post. Please make a note of it while creating future posts! $\endgroup$ – William R. Ebenezer Apr 8 at 3:39
  • $\begingroup$ It is always good to read about the experiment before going to the lab. As a result, then you don't need to use expletives. There are very good Youtube videos youtube.com/watch?v=1nAe_T5mO2o $\endgroup$ – M. Farooq Apr 8 at 3:53
  • $\begingroup$ No expletive needed alright. My apologies. And thank you :D $\endgroup$ – Paul S. Apr 8 at 4:12
  • $\begingroup$ I just want to add: the reports require bibliographical links, and I don't think they'll allow youtube videos as a reference.. $\endgroup$ – Paul S. Apr 8 at 4:14
  • $\begingroup$ I mean, I do kind of know what happens. The types of reaction taking place, but I have to back it up with bibliographical references. $\endgroup$ – Paul S. Apr 8 at 4:25
1
$\begingroup$

Any good general chemistry textbook has a chapter on electrolysis. If you wish to add more scholarly work check the Journal of Chemical Education. https://pubs.acs.org/action/doSearch?text1=Electrolysis&quickLinkYear=&quickLinkVolume=&field1=Title&type=within&publication=346464552

In the first part you electrolyze a solution of salt. Check the half cell reactions from the text: What happens at the cathode and what happens at the anode?

Water is reduced at the cathode and -OH ions are produced. This makes your salt solution basic. In the second part, your lab requires you to estimate how much base was produced.*

Essentially you do a titration of NaOH with standardized HCl. The end point is estimated by a pH meter. Look up any general chemistry textbook again for titration of a base with HCl using a pH meter. The technique is called pH titration. You did a very rough version of a pH titration.


  • Depending on the conc. of NaCl, either chlorine or oxygen is produced at the anode.
$\endgroup$
  • $\begingroup$ Thanks for the comment. Just 20 minutes ago, I found a nice resource. "Chemistry - The Central Science" 14th edition in SI units by Brown had all I needed, I think. There's almost all of what I needed on pH and acid-base stuff on chapter 16. Now, on electrolysis, I guess that's a little more advanced so it's until chapter 20, section 9 (20.9) that there's a whole section on electrolysis. And yes!, now I know I titrated the solution with the Phenolph, pretty cool.. $\endgroup$ – Paul S. Apr 8 at 5:28

Not the answer you're looking for? Browse other questions tagged or ask your own question.