Topic 9 Seperate Chemistry 2 Flashcards

1
Q

What colour do these ions turn when under a blue flame

Lithium ions-
Sodium ions-
Potassium ions-
Calcium ions-
Copper ions-

A

Li+ red flame
Na+ yellow flame
K+ lilac flame
Ca+ orange-red flame
Cu+ blue-green flame

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2
Q

What colour precipitate is formed when you add sodium hydroxide(NaOH) to these metal compounds
Aluminium-
Calcium-
Copper-
Iron(II)-
Iron(III)-

A

Al3+ white at first but goes colourless in excess of NaOH
Ca2+ white
Cu2+ blue
Fe2+ green
Fe3+ brown

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3
Q

What is the test for ammonia

A

Add sodium hydroxide to it and heat it and should give off ammonia gas which can be detected by holding damp red litmus palate over it and will turn blue
Also has distinctive smell

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4
Q

Why must a test for every ion be unique

A

To be able to differentiate between them

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5
Q

How do you test for carbonate ions

A

Add a dilute acid and then that should cause a fizz which is the carbon dioxide made then use limewater test to test for the carbon dioxide

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6
Q

How do you test for sulfate

A

Add dilute hydrochloric acid
Then add barium chloride solution and a white precipitate should be formed

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7
Q

How do you test for chloride, bromide, and iodide ions

A

Add some dilute nitric acid with few drops of silver nitrate solution

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8
Q

What colour do precipitates of chloride, bromide, and iodide produce

A

Chloride - white precipitate
Bromide - cream precipitate
Iodide -yellow precipitate

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9
Q

Why are instrumental methods of ions used

A

Very sensitive detect very small amounts of substance
Very fast
Very accurate and don’t involve human error

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10
Q

How does flame photometry work

A

Use intensity of a wavelength to indicate the concentration of an ion in a solution

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11
Q

How are alkanes and alkenes different

A

Alkenes contain double bonds and alkanes don’t

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12
Q

What is the general formula for an alkane

A

C n H 2n+2

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13
Q

What is the general formula for an alkene

A

C n H 2n

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14
Q

How are alkanes saturated

A

They have formed as many bonds as they can and have no double bonds

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15
Q

Megan (meth)
Eats (eth)
Peanut (prop)
Butter (but)

A
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16
Q

How many carbon and hydrogen atoms would Ethane have

A

C 2
H 6

17
Q

How many carbon and hydrogen atoms would Butane have

A

C 4
H 10

18
Q

How many carbon and hydrogen atoms would Propene have

A

C 3
H 6

19
Q

How many carbon and hydrogen atoms would Ethene have

A

C 2
H 4

20
Q

What is the functional group of an alkene

A

C=C

21
Q

How are alkenes unsaturated

A

They have bonds double which can open up allowing 2 carbon atoms to bond with other atoms

22
Q

What does but-2-ene show about the double bond

A

Shows that the double bond is located in the second carbon bond

23
Q

When you add an alkene to bromine water what happens to the colour and structure

A

When mixed the alkene will decolourise bromine water from orange to colourless
Bromine is added across the alkene double bond

24
Q

How is bromine water used to distinguish between an alkene and an alkane

A

Alkane are saturated with no double bonds and won’t react with bromine water and stay orange and alkene will react and change its colour

25
Q

What happens during complete combustion of alkanes and alkenes

A

They burn in oxygen to form carbon dioxide and water
Ethane + Oxygen —> carbon dioxide + water

26
Q

What is a polymer

A

Substances of high average relative molecular mass made of small repeating units

27
Q

How can ethene molecules combine in addition polymerisation

A

Open up their double bonds to form polymer chains

28
Q

What is the polymer of ethene called
C 2 H 4

A

Poly(ethene)
(C 2 H 4)n

29
Q

What does PVC stand for

A

Poly(chloroethene)

30
Q

What does PTFE stand for

A

Poly(tetrafluoroethene)

31
Q

H H H H
| | | |
C=C Ethene (-C—C-)n Poly(ethene)
| | | |
H H H H

A