Organic Analysis Flashcards Preview

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Flashcards in Organic Analysis Deck (12)
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1
Q

Describe a test for alkenes.

A

Add bromine water, decolourises if bromine is present.

2
Q

Describe a test for halogenoalkanes.

A

Warm the sample with aqueous NaOH, hydrolysing it to produce a halide ion. Add HNO3 (removes impurities) and finally add Tollen’s reagent. White precipitate shows a chloroalkane, cream preticipate shows a bromoalkane, yellow precipitate shows a idoalkane.

3
Q

Describe a test for alcohols.

A

Add potassium dichromate. Colour change fro orange to green if a primary or secondary alcohol is present.

4
Q

Describe a test for an aldehyde.

A

Add Tollen’s reagent. Silver mirror will form if an aldehyde is present.

5
Q

Describe a test for a carboxylic acid.

A

Add aqueous solution of sodium hydrogencarbonate. Effervescence is carboxylic acid is present.

6
Q

What does the mass spectrometer show and what is the information used to find?

A

Measures the relative abundance which can then be used to calculate the relative atomic mass.

7
Q

What does the vertical axis of the mass spectrum show

A

The relative abundance

8
Q

What does the horizontal axis of the mass spectrum show?

A

The mass/charge ratio of the ions reaching the detector.

9
Q

What is high resolution mass spectrometry used for?

A

Determining the precise mass of a compound so the identity of the substance can be deduced.

10
Q

How does infrared spectrometry allow identification of functional groups.

A

By seeing which wavelengths have been absorbed

11
Q

What is the fingerprint region?

A

The area of an infrared spectrum between 400cm^-1 and 1500cm^-1 which is unique for each compound.

12
Q

How does infrared specrometry work?

A

All bonds have their own unique frequency of vibration. A beam of infrared radiation is passed through a sample, the radiation emerges and is missing the frequencies that correspond to the types of bond found in the sample and plots a graph of transmittance against frequency of radiation.