C10 Flashcards

(31 cards)

1
Q

Purity

A

A pure substance is one that is made up of just one substance. That substance can be either an element or compound

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2
Q

What is purity not?

A

-Its not referring to chemical purity

-e.g. orange juice advertised as pure

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3
Q

What are the fixed points of an element or compound?

A

The melting and boiling points

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4
Q

Use of melting and boiling points:

A

-to identify pure substances

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5
Q

Test for purity of water:

A

-is that its melting point is 0 degrees and its boiling point is exactly 100 degrees

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6
Q

Melting and boiling points of an impure substance:

A

Impurities tend to lower the melting points of a substance and raise the boiling points

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7
Q

Melting point of purified sample of caffeine:

A

234-237 degrees

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8
Q

Melting point of impure sample of caffeine:

A

180-220 degrees

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9
Q

What is a formulation?

A

A mixture that has been made of definite proportions, designed to give a product the best properties to carry out a function

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10
Q

Examples of formulations:

A

Fuels, alloys, fertilisers, cosmetics, food products

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11
Q

Formulations in tablet form:

A

Aid their dissolving at the most effective place in the digestive tract

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12
Q

What do paints contain:

A

-pigment, to provide colour
-a binder, to help paint attach
-a solvent, help pigment spread

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13
Q

What do washing up liquids contain?

A

-a surfactant, to remove the grease

-water, to thin out the mixture so it squirts easily

-colouring and fragrance addictives

-rinse agent, to help water drain off

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14
Q

What might chromotography be used for?

A

To seperate and identify mixtures of amino acids

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15
Q

Amino acids

A

They are colourless but appear as purple spots on paper when sprayed with a locating agent and dried

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16
Q

Rquired practical for paper chromotography?

A

Seperate dyes in inks or food colourings

17
Q

What does chromotography always involve?

A

Mobile phase and stationary phase

18
Q

Process of chromotography:

A

-The mobile phase moves through the stationary phase
-each component in the mixture will have a different attraction for the mobile phase and stationary phase
-substance with stronger attraction to mobile phase will travel a greater distance in a given time
-substance with stronger attraction to stationary phase will travel less

19
Q

What is the mobile phase in paper chromotography?

20
Q

What is the stationary phase in paper chromotography?

21
Q

What will the results be if the unknown sample is a mixture of compounds?

A

There will be more than one spot formed

22
Q

What does a single spot suggest?

A

Its a pure substance

23
Q

Rf (retention factor) equation

A

Distance moved by substance/distance moved by solvent

24
Q

Rf values:

A

Can be measured and matched against databases to identify substances

25
Test for hydrogen
A lighted splint pops
26
Example of equation to make hydrogen gas to test:
Zince + sulfuric acid ➡️ zince sulfate + hydrogen
27
Test for oxygen
A glowing splint relights
28
How to test for oxygen?
-collect 15cm^3 hydrogen peroxide solution in a conical flask -add manganese oxide from the end of spatula -inset glowing splint in the mouth of flask
29
Test for carbon dioxide?
Limewater turns milky (cloudy white)
30
How to test for carbon dioxide?
Bubble carbon dioxide gas through limewater using approapriate apparatus
31
Test for chlorine?
Damp blue litmas paper turns white (as it gets bleached)