CCEA A-Level Chemistry 1110
Formulae, Equations and Amounts of Substance
Atomic Structure
Bonding
Intermolecular Forces and Structure
Shapes of Molecules and Ions
Redox
The Halogens
Acid-Base Titrations
Qualitative Tests
Formulae and Amounts of a Substance
Nomenclature and Isomerism in Organic Chemistry
Alkanes
Alkenes
Halogenoalkanes
Alcohols
Infrared Spectroscopy
Energetics
Kinetics
Equilibrium
Group II Elements and Their Compounds
Lattice Enthalpy, Entropy and Free Energy
Rates of Reaction
Equilibrium and Acid-Base Equilibria
Isomerism
Aldehydes and Ketones
Carboxylic Acids
Derivatives of Carboxylic Acids
Aromatic Chemistry
Spectroscopy and Chromatography
Volumetric Analysis
Transition Metals
Electrode Potentials
Amines
Amides and Polymers
Amino Acids and Proteins
Spectroscopy and Chromatography
Paper and thin-layer chromatography
- 3 things to know
- Unit A2 2
Overview
Two phases in paper chromatography, two phases in thin-layer chromatography and two-way chromatography.
What you need to know
Answer each one before you reveal it.
What are the two phases in paper chromatography?
What are the two phases in thin-layer chromatography?
Questions from this subtopic
Each one with the model answer underneath.
- 1
On what principle does all chromatography separate a mixture?
Model answer
The components distribute themselves differently between a stationary phase and a mobile phase, so each travels at its own rate.
- 2
What are the two phases in paper chromatography?
Model answer
The water held in the fibres of the paper is the stationary phase, and the solvent moving through it is the mobile phase.
- 3
What are the two phases in thin-layer chromatography?
Model answer
A thin layer of silica or alumina on a plate is the stationary phase, and the solvent rising through it is the mobile phase.
- 4
Why is the base line drawn in pencil?
Model answer
Ink would dissolve in the solvent and travel up the plate with the sample.
- 5
Why must the base line start above the level of the solvent?
Model answer
If the spots were below the surface they would dissolve into the solvent in the tank rather than move up the plate.
- 6
Why is the tank covered during a run?
Model answer
To keep the atmosphere inside saturated with solvent vapour, so the solvent does not evaporate from the plate and distort the separation.
Other ways to work this
The same content, four other ways.
What is inside Levo
Six ways to work the same material.
Every question in Spectroscopy and Chromatography, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
Or £46 a year, about £3.83 a month. Cancel anytime.