Connie C.

asked • 09/29/17

Rf values TLC - Organic Chemistry LAB

For my developing solvent, I used 6:4 hexane:ethyl acetate. For my reference spot, I mixed some salicylic acid and ethyl acetate. And for my test spot, I used some impure aspirin and ethyl acetate.

After letting my TLC plate develop in the developing solvent, marking the solvent line, and letting it dry, I put the TLC plate under a UV to marked the spots.

I got 3 spots total, 1 spot for my reference and 2 spots from my impure sample of aspirin.
Reference spot traveled 2.47 cm
Spot 1 from impure aspirin samples traveled 1.51 cm
Spot 2 from impure aspirin sample traveled 2.45 cm

And for my Rf values I got…
Rf (reference - salicylic acid and ethyl acetate) = 2.47 ÷ 5.30 = 0.466
Rf (1.51 spot) = 1.51 ÷ 5.30 = 0.2849056604 = 0.285
Rf (2.45 spot) = 2.45 ÷ 5.30 = 0.4622641509 = 0.462

Reading the lab handout again, I’m suppose to get a Rf value of 0.20 to 0.35…

So, did I do the lab wrong? Was the 6:4 hexane:ethyl acetate too polar? I’m so confused! Can someone explain to me what my values mean???

1 Expert Answer


J.R. S. answered • 09/30/17

Ph.D. University Professor with 10+ years Tutoring Experience

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