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Chemistry 11 > C10 Chemical Analysis > Flashcards

C10 Chemical Analysis Flashcards

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1
Q

What is a pure substance

A

It is made up of just one substance

That can be either an element or a compound

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2
Q

How can you identify pure substances

A

Using boil8ng points and melting points
Pure substances have characteristic specific temperatures at which they melt and boil
Eg water melts at 0 and boils at 100c
The melting and boil8ng point of A mixture will vary depending on the composition of the mixture

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3
Q

How do impurities affect boiling point and melting point

A

Impurities tend to lower melting point and raise its boil8ng point
The more impurities the greater the difference from the fixed point of the pure substance
Eg purified caffeine melting range is 234-237c
Crude caffeine extracted fro tea is 180-220 showing it is impure

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4
Q

What is a formulation

A

A formulation is a mixture that has been designed to produce a useful product eg medicine or drugs
Potentially compromising 5-10% of the active drug that relieves the illness

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5
Q

Why are tablets containing sweeteners and smooth coatings

Why are there other fillers

A

To aid swallowing

To aid their dissolving at most effective place in digestive tract

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6
Q

What are paints and what do they contain

A

Formulations
Pigment to provide colour
Binder to help piano stick and form protective film when dry
Solvent to help pigment and binder spread well during painting by thinning them out

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7
Q

What are other typical formulation

A

Washing up liquid- includes surfactant (detergent), water to thin out, colour fragrance to improve appeal and rinse agentto help water drain off
Also fuels, alloys, pesticides, cosmetics, food products

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8
Q

What is an element

A

A pure substance that contains only one type of atom eg Argon, Au(gold), H2, F2, Cl2, S8

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9
Q

What is a compound

A

Two or more elements chemically bonded as a pure substance

Eg NaCl, H2O

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10
Q

What is an atom

A

Simplest pure chemical building block eg H

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11
Q

What is a mixture

A

Two or more elements or compounds not chemically bonded eg Air, sea water, orange juice
Not pure because not chemically bonded

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12
Q

What is a molecule

A

Two or more atoms joined by chemical bonds

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13
Q

What is an alloy

A

Mixture of two elements eg iron and carbon make steel

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14
Q

Is spring water pure?

A

No it is a mixture with several substances listed on the the label not just H2O

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15
Q

Why is salt placed on roads in winter months

A

It melts the ice because it creates a mixture with a lower range of freezing points much lower than ice/ water

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16
Q

Why is pure gold not suitable fi4 jewellery

A

It is very soft and bendy when pure

17
Q

Why is gold alloy suitable

A

The alloy is harder because it contains different sized atoms that make it harder for layers to slide over each other

18
Q

What is purity

A

The amount of a substance in a mixture

19
Q

What is chromatography

A

Separating mixtures according to their solubility

20
Q

What is the equation for retaining factor?

A

Distance substance travels ➗distance solvent front travels

21
Q

How does chromatography work?

A 
Different forms include
Paper chromatography 
Thin layer chromatography- TLC
column chromatography 
Gas chromatography
22
Q

What are the 2 stages of chromatography

A
  1. Stationary phase - the part that does not move - paper

2 mobile phase - the part that moves - water or solvent

23
Q

What is the process

A

Starting line drawn on paper in pencil so it doesn’t dissolve
Small spots of each sample placed on starting line
Paper left vertically in solvent but solvent is below level of spots
Solvent soaks up paper for few minutes until near top
Paper removed to dry
Substances separate because have different attractions to paper and solvent - ie if strong attraction to solvent = move a long way

24
Q

What is the test for hydrogen
Use of hydrogen
Why does it pop

A

Lighted splint gives off squeaky pop
Eg Zinc + sulfuric acid => zinc surface + hydrogen

Used for fuel for vehicles
Pops because the lighted splint cause small explosion of hydrogen burning with oxygen

25
Q

What is the test for oxygen

What is a use

A

Relighting a glowing splint
Hydrogen peroxide decomposing with manganese oxide catalyst makes water and oxygen
Helps with breathing

26
Q

What is a test for carbon dioxide

What use

A

Limewater goes cloudy - puts out a lit splint
React marble chips/ calcium carbonate with dilute hydrochloric acid
Safety - wear eye protection
Use putting out fires

27
Q

Test for chlorine

Use

A

Damp blue litmus paper bleached or turns white
Safety - toxic gas
Hydrochloric acid and potassium manganate crystals in boiling tube gives off chlorine gas
Killing bacteria

Chemistry 11 (11 decks)

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