C8 - Chemical Analysis Flashcards
How is purity defined differently in chemistry compared to everyday language?
In everyday language, purity means a substance is in its natural state without anything added. In chemistry, a pure substance contains only one compound or element throughout
Examples include pure milk or beeswax in everyday context.
What does a chemically pure substance’s melting or boiling point indicate?
A chemically pure substance will melt or boil at a specific temperature
This can be tested by measuring the melting or boiling point and comparing it with known values.
What happens to the melting point and boiling point in the presence of impurities?
Impurities lower the melting point and increase the melting range. They also increase the boiling point and may cause boiling at a range of temperatures.
What are formulations in chemistry?
Formulations are mixtures with exact amounts of components designed for a specific purpose
They are made by following a ‘formula’ or recipe.
What components typically make up paint formulations?
Paint formulations usually include:
* Pigment
* Solvent
* Binder (resin)
* Additives
How do formulations play a role in the pharmaceutical industry?
Formulations ensure drugs are delivered to the correct part of the body at the right concentration and have a suitable shelf life.
Where can formulations be found in everyday life?
Formulations can be found in:
* Cleaning products
* Fuels
* Cosmetics
* Fertilizers
* Metal alloys
* Food and drink
True or False: A formulation’s packaging can provide information about the composition of its components.
True
Fill in the blank: A pure substance in chemistry contains only _______.
[one compound or element]
What is chromatography?
An analytical method used to separate substances in a mixture.
What are the two phases in chromatography?
- Mobile phase
- Stationary phase
What is the mobile phase in chromatography?
The phase where the molecules can move, always a liquid or gas.
What is the stationary phase in chromatography?
The phase where the molecules can’t move, can be a solid or thick liquid.
What forms during a chromatography experiment?
An equilibrium between the mobile and stationary phases.
How does the mobile phase move in chromatography?
It moves through the stationary phase, carrying dissolved substances with it.
What determines how quickly a chemical moves in chromatography?
How it’s distributed between the two phases.
What happens to chemicals that spend more time in the mobile phase?
They will move further up the stationary phase.
What is a key characteristic of a pure substance in chromatography?
It will only ever form one spot in any solvent.
What is the stationary phase during paper chromatography?
The chromatography paper (often filter paper).
What is the mobile phase in paper chromatography?
The solvent (e.g., ethanol or water).
What two factors influence how long molecules spend in each phase?
- Solubility in the solvent
- Attraction to the paper
Fill in the blank: Molecules with a higher _______ in the solvent will spend more time in the mobile phase.
[solubility]
True or False: A component that is less attracted to the paper will move less distance in chromatography.
False
