Reef Chemistry Question of the Day #99 TDS

[Randy Holmes-Farley]

Reef Chemistry Question of the Day #99

Which of the following will not increase the TDS reading (as ppm TDS using a TDS meter) when put into freshwater at pH 7?


A. Sodium
B. Calcium
C. Ethanol (alcohol)
D. Nitrate
E. Acetic acid (vinegar)

Good luck!


























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[Reefer1978]

No clue but going to guess C.

 

[Maximo]

E vinegar!

 

[Cory]

This is hard one. Minerals all have charge, so electrical conductivity would be measured via calcium and sodium and nitrate I beleive. So those arnt it.

It's a tough choice but it's gotta be ethanol or vinegar... Goes to tds meter and poors vinegar in water... Yes vinegar raised the tds! So I'm guessing Ethanol!

 

[tonizzy22]

Answer is C ethanol is not charged and I believe a tds meter will not detect it same as sugar

 

[beaslbob]

wild guess
c

(see https://www.youtube.com/watch?v=4WillWjxRWw)

 

[Steven@]

C is the answer

I really enjoy and get great knowledge from the question and the answers other provide. thanks for doing this forum.

 

[Randy Holmes-Farley]

And the answer is...C. Ethanol (alcohol)

As most of you noted, ethanol carries no electric charge, so cannot be detected by a TDS meter. Ethanol is CH₃CH₂OH

Acetic acid isn't charged wither, but in water at pH 7 it will dissociate into acetate and H+, both of which conduct and would be detected:

CH₃CO₂H --> CH₃CO₂^- + H⁺

Sodium (Na⁺), calcium (Ca⁺⁺), and nitrate (NO₃^-) are all charged and detectable with a TDS meter.

Happy Reefing!