ISA

Question 1

what does combustion tell you?

Answer 1

A smokey flame means a high carbon to hydrogen ratio.

Clean flame low carbon to hydrogen ratio.

Question 2

What does addition of a solution to water tell you?

Answer 2

Two layers form meaning no OH or a high molar mass(4 carbon +) for acid or alcohol.
Dissolves fully meaning hydrogen bonds.

Question 3

Addition to bromine water.

Answer 3

Two layers form and brown water goes colourless. C=C present.

Question 4

If ethanol and silver nitrate and dilute nitric acid is added, what does the result tell you?

Answer 4

precipitate will form
white=C-Cl
Cream=C-Br
Yellow=C-I

Question 5

add concentrated sodium hydroxide and ethanol. Pass gas produced through bromine water.

Answer 5

Brown bromine goes colourless. meaning H-halogen is eliminated forming an alkene.

Question 6

Ammonia solution is added.

Answer 6

Dissolved in dilute ammonia= chloroalkane
dissolves in concentrated ammonia=unknown is bromoalkane
doesn’t dissolve= iodoalkane..

Question 7

2.4 dinitrophenylhydrazine is added.

Answer 7

yellow or orange precipitate means aldehyde or ketone.

Question 8

Fehling’s or benadict’s is added it warmed.

Answer 8

Red precipitate(an aldehyde) stays blue (ketone)

Question 9

Tollen’s reagent and warm.

Answer 9

silver mirror forms(aldehyde) solution stays colourless(ketone)

Question 10

acidified potassium dichroamte (VI)

Answer 10

orange goes green(aldehyde) stays orange(ketone)

Question 11

acidified potassium manganate (VII)

Answer 11

purple solution de-colourises ( aldehyde). Solution stays purple(it is a ketone)

Question 12

what are primary alcohols oxidised to?

Answer 12

aldehydes. Secondary to ketones.

Question 13

ehthanol (or other alochol) and sulphuric acid added and warm. Add sodium carbonate.

Answer 13

If fizzing and smells glue/fruity is carboxylic acid(ester has formed) if not alcohol.

Question 14

what is the iodoform test?

Answer 14

an organic alcohol or carbonyl compound and a solution of iodine and sodium hydroxide. The solution is then left to stand.

Question 15

what are the results from the iodoform test?

Answer 15

If already proven to be a carbonyl compound.=contains CH₃C=O
know it to be an aldehyde=it is ethanal
know it be be an alcohol=contains CH₃CH(OH) group like propan-2-ol

Question 16

Add sodium to unkown solution in evaporating basin.

Answer 16

Bubbles evolved, sodium dissolves and white solid forms.= Contains OH group so it carboxylic acid or alcohol.

Question 17

add solid phosphorus (v) chloride and test any gas evolved with litums paper or ammonia on the end of a glass rod.

Answer 17

Steamy fumes form. White smoke formed from ammonia, paper goes red.
means is contains OH group and is an alcohol or carboxylic acid.

Question 18

add ethanoic acid and a few drops of concentrated sulphuric acid to unknown and warm. add sodium carbonate solution.

Answer 18

fizzing/ smells of glue/fruity. It is an alcohol. (ester has formed) not a carboxylic acid.

Question 19

warm gently with acidified potassium dichromate

Answer 19

orange solution goes greeen= primary or secondary alcohol and not a carboxylic acid.
you must have already have shown that it contains a OH group as an aldehyde will also turn it green.

Question 20

what are the tests for acid chlorides?

Answer 20

add to water in test tube and add nitric acid and aqueous silver nitrate. steamy white fumes=acid chloride
add to ethanol and sodium carbonate.= fruity glue smell= acid chloride.