Question

1. What would be the result of failing to mark the solvent front after developing a TLC plate? Would this affect your ability to calculate component Rf values? Why or why not?

2. What would happen if your origin line was oriented so low on the TLC plate that when it was lowered into the TLC chamber it was positioned below the level of the developing solvent (eluent)?

3. Assuming that the separation of a binary mixture in ideal circumstances (concentrated spotting) would be relatively small (less than 0.5 cm), what would be the result of applying too large a spot of this mixture to the TLC plate? How would it affect your ability to distinguish one component from the other on the plate? How would it affect your Rf values? Draw a sample TLC plate to help illustrate your answer.

4. Unknown compound Q is spotted on a TLC plate that is then developed in cyclohexane. The solvent front is measured at 5.2 cm and the distance traveled by compound Q is measured at 3.4 cm. A sample of acetaminophen is spotted on a TLC plate that is then developed in cyclohexane. The solvent front is measured at 4.15 cm and the distance traveled by acetaminophen is measured at 2.70 cm. What can be determined about the identity of compound Q in light of this data?

5. Describe how TLC could be used to monitor a reaction’s progress (product & byproduct formation) in a research/teaching laboratory.

Answer 1

1. Surely it will affect our ability to calculate Rf values. Without solvent front Calculating Rf will not be accurate. Hence marking the solvent front is authentic.

2. if origin line was oriented so low on the TLC plate it will immerse into the solvent medium resullting compound will dissolve into solvent instead of eluting.

3. Compound having minimum Rf difference and applying too large spot of this mixture will be look like a single spot and you can not recognize whether there is 2 spots

4. compound Q and acetaminophen having same Rf value

5. TLC will show different Rf value for starting material and product. As well we can come to know howmany product was formed including byproudct. When we have product standard exactly we can come to know which one is the expected product

Here E (starting material) showing diff Rf value from F (Reaction mixture). G is product standard showing Same Rf value with reaction mixture. another new in reaction mixture will be byproduct.