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?

$\endgroup$

closed as unclear what you're asking by Mithoron, Tyberius, Zhe, Todd Minehardt, A.K. Apr 9 at 1:02

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ 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.