Chromatography & Testing For Gases Flashcards
What is chromatography?
An analytical technique used to separate substances in a mixture to identify them
What is the mobile phase in paper chromatography?
The solvent (e.g., water or ethanol) that moves up the paper
What is the stationary phase in paper chromatography?
The paper, where molecules bind and cannot move
How do you calculate the Rf value?
Rf=
Distancetraveledbythesolvent
____________________________
Distancetraveledbythesubstance
What is a chromatogram?
The pattern of spots left on the paper after chromatography
Why do different dyes travel at different rates?
- differences in solubility
- attraction to the paper
What happens if a chemical isn’t soluble in the solvent?
- It stays on the baseline
- Does not move up the paper
Why might Rf values change for the same substance?
- A change in the solvent
- A change in paper
How can chromatograms help identify substances?
By comparing Rf values to those in a data book under the same conditions
What does one spot on a chromatogram indicate?
The sample is a pure substance
How do you test for chlorine gas?
Expose it to damp blue litmus paper
What happens when damp blue litmus paper is exposed to chlorine gas?
The damp litmus paper turns
- red,
- then bleaches white
What safety precautions are required for testing chlorine gas?
- Wear a gas mask
- Do the experiment in a fume cupboard
How do you test for oxygen gas?
- Bubble it though limewater
- Expose it to a glowing splint
What happens when a glowing splint is exposed to oxygen gas?
The glowing splint will relight
