LAB TLC NOTEBOOk :(

Objective - (TLC) thin layer chromatography experiment is a technique to seperate chemical mixtures in order to analyze based on characteristics of polarity. The interpretation and visualization of this experiment will be done using both a UV light and iodine chamber. The results documented will then be used to identify unknown compounds with a pure known compound.

Compound List: + MO + Formula + density + MP + BP

Acetyl Salic Acid(aspirin) = 180.158 g/mol

DRAW APPaRATUS + SET UP

PROCEDURE

Prelab notes - boring caca butt stuff

Chromatography - Seperate chem mixtures between stationary and mobile -

Molecules are in contact with both phases(stationary and mobile)

Molecules with weak interactions with stationary will move quikcly

And molecules with strong interactions with stationary will move slowly -

Faster movement - weaker interaction

Thin layer chromatography thin layer of material

mobile is pulled up the stationary - solvent/analyte

Black ink is placed on tlc plate and then will move to reveal color lol

types of stationary

Normal phase is polar = silica gel or alumina

Reverse phase is non polar - silicagel capped

Polar compounds stick to polar faces and vise versa

MOBILE PHASE FOR TLC

must be readily dissolve analyte not too polar

not oo polar doesnt move too fast or too slow

WRITE IN

The more similar the analytes are to the stationary the smaller the distace they travel

PRODECURE -

Prepare

  1. get a plate and draw a line at the bottom about a 1cm at the bottom in pencil to avoid contamination. use pencil to draw on plate

  2. add perpendicular has marks depending on samples. one of them can be a reference used to compare.

  3. Spot a small amount of analyte on the hash mark. Small glass capilary and draw a small amount of solution onto the capilary . Not too large

  4. Wait till spots dried and solvents evaporated

  5. Can speed up using an air stream

  6. Devloping the plate is next - take a beaker and add .5cm eluent to beaker or jar

  7. Transfer the TLC plate using tweezers

  8. Ensure that the line of the plate is above the solvent to avoid analytes from disolving

  9. Add a filter paper prior to placing tlc plate in the beaker to evoporate some of the solvent

  10. Cover the beaker using alumiun foil.

  11. Wait till solvent has moved up and solvent from will develop whihch is the max distance the thing will travel

  12. Immediately mark the solvent fron with a pencil

  13. Circle any visible spots in pencil after it dries

  14. Place the tlc plate under UV lgith and circle any spots dark or colored in pencil

  15. Place tlc plate into a jar that has idondine I2 in a fume hood carelfuly lower plate into idonde with tweezers

  16. wait till spots turn dark and remove plate and circle spots in pencil quickly

Record a sketch of a TLC plate

and calculation of retention factor Rf

Dont touch the silica gels with bare hands

draw lines lightly

spot small spots of roughly equal size

dont let solvent fron reach the very front of the plate

dont let urself expose to UV

use I1 in fume hoods

Determine purity of a compound

Spot known pure compound

spot same compound of unknown purity

develop and visualize

compare your own sample with a pure one of the same compound;

One spot in ur unknown and one spot in ur pure in the same length will most likely be pure

Prelimary indeitifcation -

Over time we can take the reaction solution and spot it to our pure one. So if we start and uknown and pure one and wait the same time it will travel either same or different length.