chemistry 2

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  • Created by: Oyinda14
  • Created on: 19-06-18 21:40
What is a pure substance?
A substance that contains 1 element or compound
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How to test a pure substance?
Measure melting or boiling point and compare it to melting or boiling point the closer your value is to the actual melting or boiling point the purer your substance is
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What are formulations?
Formulations are useful mixyures for a precise purpose
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What can impurities do to melting/boiling point
They can lower melting points and increase melting range and increase boiling points and lead to a range of temperatures
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Formulation e.g
paint
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What are the formulations of paint?
pigment- gives paint colour, solvent- used to dissolve other components and alter the viscosity, binder- forms a film that holds pigment in place after painted on, Additives- Add to further change (physical and chemical properties)
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Why are formulations important?
For the pharmaceutical industry, by altering formulation of pill, chemists makes sure that it is delivered to the right part of the body, with right concentration and it is consumable and has enough shell life
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Where are formulations found?
Fuels,cosmetics,fertilisers
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Testing for chlorine
chlorine bleaches damp litmus paper white- if it turns red first it is acidic
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Testing for Oxygen
Glowing splint in test tube of oxygen, oxygen will relight glowing splint
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Testing for Carbon Dioxide
Bubbling Carbon dioxide through aqueous solution of calcium hydroxide cause solution to turn cloudy
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Testing for Hydrogen
Burning splint int test tube of hydrogen will make squeaky pop sound
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What is chromatography?
Method used to separate substances in a mixture and identify substances in it
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Mobile phase
Where molecules can move - liquid or gas
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stationary phase
where molecules can't move- can be solid
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What is Rf value?
Rtaio between distance travelled by dissolved substance and distance travelled by solvent
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Rf fromula
distance travelled by substance / distance travelled by solvent
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Rf value is affected by solvent
Rf value is dependant on solvent you use, if you change solvent Rf value for substance will change
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Time spent on molecules depends on what 2 things?
How soluble they're in solvent and how they attracted they are to the paper
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Why must start line be drawn in pencil?
Pencil doesn't smudge or run into solvent
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Why does there need to be a lid?
prevents solvent from evaporating
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Other cards in this set

Card 2

Front

How to test a pure substance?

Back

Measure melting or boiling point and compare it to melting or boiling point the closer your value is to the actual melting or boiling point the purer your substance is

Card 3

Front

What are formulations?

Back

Preview of the front of card 3

Card 4

Front

What can impurities do to melting/boiling point

Back

Preview of the front of card 4

Card 5

Front

Formulation e.g

Back

Preview of the front of card 5
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