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organic analysis Flashcards

(45 cards)

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1
Q

What can be used to distinguish between primary, secondary, and tertiary alcohols?

A

Acidified potassium dichromate (K,Cr,°7)

It is a mild oxidizing agent that helps identify alcohol types through oxidation reactions.

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2
Q

What happens to primary and secondary alcohols when oxidized by acidified potassium dichromate?

A

They are oxidized and the dichromate turns from orange to green

The orange color indicates the presence of Cr2O7^2- ions, which change to Cr3+ ions.

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3
Q

What is the oxidation behavior of tertiary alcohols with acidified potassium dichromate?

A

Tertiary alcohols cannot be oxidized using dichromate

This differentiates them from primary and secondary alcohols.

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4
Q

What is the problem when testing primary and secondary alcohols with dichromate?

A

Both give the same color change

This necessitates further testing to distinguish between the products.

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5
Q

What method is used to collect products produced upon oxidation of primary and secondary alcohols?

A

Fractional distillation

This method separates components based on boiling points.

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6
Q

What is produced from the oxidation of primary alcohols?

A

Aldehyde

Aldehydes are characterized by the functional group -CHO.

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7
Q

What is produced from the oxidation of secondary alcohols?

A

Ketone

Ketones are characterized by the functional group >C=O.

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8
Q

What solution can be used to distinguish between aldehydes and ketones?

A

Fehling’s solution

Fehling’s solution is also known as Benedict’s solution.

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9
Q

What type of agent is Fehling’s solution?

A

Oxidising agent

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10
Q

What happens to Fehling’s solution when it reacts with aldehydes?

A

Goes from blue solution to brick red precipitate (Cu2O)

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11
Q

What happens to Fehling’s solution when it reacts with ketones?

A

Remains blue

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12
Q

What color is Fehling’s solution before the reaction?

A

Blue

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13
Q

What is the precipitate formed when aldehydes react with Fehling’s solution?

A

Brick red precipitate (Cu2O)

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14
Q

True or False: Ketones can be oxidized by Fehling’s solution.

A

False

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15
Q

Fill in the blank: Fehling’s solution is used in a _______ water bath during testing.

A

Hot

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16
Q

What reagent is used to distinguish between aldehydes and ketones?

A

Tollens’ reagent

Tollens’ reagent can be prepared and then used for this purpose.

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17
Q

What is the composition of Tollens’ reagent?

A

[Ag(NH3)2]+

This complex is used to test for the presence of aldehydes.

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18
Q

What happens when Tollens’ reagent is added to an aldehyde?

A

Silver reduces to form a silver coating inside the flask

This indicates a positive test for aldehydes.

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19
Q

What is the result of adding Tollens’ reagent to a ketone?

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A

No silver precipitate forms

This indicates a negative test for ketones.

20
Q

What is the initial appearance of silver nitrate solution?

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A

Colourless

This is the state of the solution before any reaction occurs.

21
Q

What precipitate forms when NaOH is added to silver nitrate solution?

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A

Pale brown precipitate

This is an intermediate step in the testing process.

22
Q

What must be added to the pale brown precipitate to dissolve it?

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A

Dilute ammonia

This step is crucial for completing the test.

23
Q

What safety precaution is mentioned regarding the heating of aldehydes and ketones?

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A

Do not use a Bunsen flame

Aldehydes and ketones are flammable substances.

24
Q

What is the procedure for testing an aldehyde or ketone with Tollens’ reagent?

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A

Add the aldehyde or ketone to Tollens’ reagent and place in a hot water bath

This method ensures controlled heating.

25
What is the test for alkenes?
Reacting alkenes with bromine water ## Footnote The presence of a double bond in alkenes allows for this reaction.
26
What is bromine water used for in the test for alkenes?
To react with the double bond in alkenes
27
What does the reaction of bromine water with an alkene produce?
A dibromoalkane
28
What happens when bromine water is added to an alkene and shaken?
A colourless solution is formed if an alkene is present
29
What is the appearance of bromine water before reacting with an alkene?
Colourless solution
30
What is the test for carboxylic acids?
Involves reacting it with a carbonate
31
What do carboxylic acids produce when reacting with carbonates?
CO2 gas and water
32
What happens when CO2 gas is bubbled through limewater?
It turns cloudy
33
What is the chemical reaction for carboxylic acids reacting with carbonates?
CO32- + 2H+ → CO2 + H2O
34
What is a suitable carbonate to use in the test for carboxylic acids?
Solid sodium carbonate or sodium carbonate solution
35
True or False: Any other acid will react with carbonates in the same way as carboxylic acids.
True
36
What must you know to draw valid conclusions about carboxylic acids?
You must know that you have a potential carboxylic acid among other organic substances
37
What is mass spectrometry used for
To find the Mr of a compound
38
What do greenhouse gases in the atmosphere absorb?
Infrared radiation ## Footnote Greenhouse gases play a crucial role in regulating Earth's temperature by trapping heat.
39
What type of radiation from the sun reaches the Earth?
Electromagnetic radiation ## Footnote This radiation is essential for life on Earth as it provides the energy necessary for photosynthesis.
40
What happens to some of the radiation absorbed by the Earth?
It is re-emitted as infrared ## Footnote This process is a key part of the Earth's energy balance.
41
Name three greenhouse gases.
* Carbon Dioxide (CO₂) * Water vapour (H₂O) * Methane (CH₄) ## Footnote These gases contribute to the greenhouse effect and global warming.
42
What is the process called when greenhouse gases absorb and re-emit radiation back towards the Earth?
The greenhouse effect ## Footnote This effect is vital for maintaining a habitable climate on Earth.
43
What human activities have increased the levels of greenhouse gases in the atmosphere?
* Burning fossil fuels * Landfill ## Footnote These activities release significant amounts of greenhouse gases, exacerbating climate change.
44
What is the gradual warming of the Earth called?
Global warming ## Footnote Global warming is a significant aspect of climate change, affecting weather patterns and ecosystems.
45
True or False: The covalent bonds in greenhouse gases absorb infrared radiation.
True ## Footnote Covalent bonds are responsible for the interaction of greenhouse gases with infrared radiation.

organic chemistry (7 decks)

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