Chemical Analysis Flashcards
Pure substance in chemistry
Something that contains only 1 compound/element throughout, not mixed with anything else
Pure substance in everyday language
Substance that hasn’t had anything added to it so is in natural unadulterated state, like pure milk
How to test purity of sample
- measure melting/boiling point
- compare with that of pure substance - data book
- closer your sample is to pure value, purer it is
Effect of impurities on melting point + range
- lower melting point
- increase melting range
Effect of impurities on boiling point + range
- increases boiling point
- sample may boil at range of temps
Formulations
Mixtures with exact amounts of components for a precise purpose
How to make formulations
- follow a formula
- add each component in precisely measured formula
Why do formulations have precise measurements
Quantity of each component contributes to properties so formulation meets required function
Example of formulations in pharmaceutical industry
- formulation of pills can be altered so that:
-drug delivered to correct part of body
-delivered at right concentration
-its consumable
-has long enough shelf life
Examples of formulations in everyday life
- fuels
- cleaning agents
- paints
- medicines
- alloys
- fertilisers
- foods
Purpose of chromotography
- separate substances in mixture
- can then identify substances
Phases of chromotography
- mobile
- stationary
Mobile phase
- molecules can move
- always liquid or gas
Stationary phase
- molecules can’t move
- can be solid or really thick liquid
What is the mobile phase in paper chromotography
The solvent
What is the stationary phase in paper chromotography
Paper
What happens when chemicals are in mobile phase in paper chromotography
- dissolve in solvent
- move a little bit
What happens when chemicals are in stationary phase in paper chromotography
- bind to paper
- don’t move
When do chemicals switch phases in paper chromotography
Continuously
What determines how much chemicals move up paper in chromotography
How much time they spend in each phase
How can you tell solubility of chemicals in paper chromotography
- the more soluble a chemical is, the more time it spend in the mobile phase
- the more time it spends in the mobile phase, the further up the paper it will go
Why do more soluble chemicals move further up page in chromotography
Molecules are less attracted to paper so spend more time in mobile phase
How to know a substance in pure from chromotography
It will only form 1 spot in any solvent
How to know substance is impure from chromotography
It will form multiple spots
