AQA Topic 8 - Chemical Analysis

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  • Created by: Grace
  • Created on: 28-05-18 17:08
Define purity
In chemistry a pure substance is something that only contains one compound or element throughout i.e not mixed with anything else
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How does the boiling/melting point of a substance indicate if it is pure or not?
A chemically pure substance will melt or boil at a specific temperature, impurities in the substance will lower the melting point and increase the melting range of your substance but impurities will increase the boiling point = boil at range of temps
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Describe a test for purity of substances
Measure a substance's melting or boiling point and compare it with the melting or boiling point of the pure substance, the closer your measured value is to the actual = the purer the substance is
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Define formulations
Useful mixtures with exact amounts of components to contribute to the properties of the formulation so that it meets its precise purpose
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Describe the formulation of paint
Paint is made of:PIGMENT - gives paint its colour,SOLVENT - used to dissolve other components and alter the viscosity,BINDER(resin) - forms a film that holds the pigment in place after its been painted on,ADDITIVES - added to change chem/phys props
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Why are formulations important in the pharmaceutical industry?
Because it enables chemists to be able to give the right dosage of a drug, it is delivered to the right part of the body and it has a long enough shelf life
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How do you know everyday food items are formulations?
On the packaging there will be a ratio or percentage of each component
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Define chromatography
An analytical method used to operate the substances in a mixture which can then be used to identify the substances
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How many phases does chromatography have? What are they called?
Two phases: 1. A mobile phase 2. A stationary phase
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Describe the mobile phase
Where the molecules can move, this is always a liquid or a gas
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Describe the stationary phase
Where the molecules can't move, this can be a solid or a really thick liquid
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What happens during a chromatography experiment involving the phases?
The substances in the sample constantly move between the mobile and stationary phase, therefore an equilbirum is formed between the two phases
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Where does the mobile phase and what happens?
The mobile phase moves through the stationary phase, and anything dissolved in the mobile phase with it
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What does the speed of how a chemical moves depend on?
It depends on how it's distributed between the two phases - whether it spends more time in the mobile phase or the stationary phase
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Other cards in this set

Card 2

Front

How does the boiling/melting point of a substance indicate if it is pure or not?

Back

A chemically pure substance will melt or boil at a specific temperature, impurities in the substance will lower the melting point and increase the melting range of your substance but impurities will increase the boiling point = boil at range of temps

Card 3

Front

Describe a test for purity of substances

Back

Preview of the front of card 3

Card 4

Front

Define formulations

Back

Preview of the front of card 4

Card 5

Front

Describe the formulation of paint

Back

Preview of the front of card 5
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