carbonyl compounds and isomerism

Question 1

what is optical isomerism

Answer 1

a type of stereoisomerism where atoms are arranged differently in space and have a chiral carbon

Question 2

what is a chiral carbon

Answer 2

a carbon atom with four different groups attached to it

Question 3

what are enantiomers

Answer 3

are mirror images and no matter how you rotate them they cannot be superimposed and are therefore achiral

Question 4

what is plane polarized light and how do you create it

Answer 4

when normal light is passed through a polarizing filter is becomes plane polarised lights which is when all the light it is vibrating in the same plane

Question 5

what is a racemate
are they optically active?

Answer 5

A racemate contains equal quantities of each enantiomer of an optically active compound and they do not show optical activity as the two enantiomers cancel each other out

Question 6

how can you test for aldehydes

Answer 6

Tollens reagent: add tollens reagent and heat it. If there is an aldehyde a silver mirror on the test tube will form
OR
Fehling’s solution :A blue solution made of copper ii ions dissolved in sodium hydroxide and if it is heated with an aldehyde the sopper ii ions are reduced to rick red precipitate of copper I oxide

Question 7

what is the name of the reducing agent used to reduce ketones and aldehydes

Answer 7

sodium tetrahybridoborate III

Question 8

what is the general equation of the reaction of acids and carbonates

Answer 8

Acid + carbonate —> water + carbon dioxide + salt

Question 9

what is the appearance of the reaction between an acid and a carbonate

Answer 9

effervescence of CO2

Question 10

what is the general equation for esterification and what are the conditions

Answer 10

H+
Carboxylic acid + alcohol —-> Ester + water

Question 11

what are the conditions for esterification

Answer 11

an acid catalyst of either concentrated sulfuric acid , HCL and H3PO4

Question 12

what are the 3 uses of esters and why are they good for the use

Answer 12

1. perfumes due to their sweet smells
2. glues and printing ink due to the fact they are polar
3. plasticisers to make plastics more flexible

Question 13

what are the two types of hydrolysis of esters and what are the conditions of each

Answer 13

acid- reflux of the ester with a dilute acid like HCL or H2SO4

base- reflux the ester with a dilute alkali such as NaOH and

Question 14

explain why fats are solid at room temp and why oils are liquid

Answer 14

fats are solid as they have hydrocarbon chains fitting neatly together increasing the van der waals between them and therefore a higher melting point

oils have unsaturated hydrocarbon chains and the double bonds cause the chains to bend and therefore decrease the van der waals and have a lower melting point

Question 15

what are the reactants and conditions of making biofuel

Answer 15

oils + methanol in the presence of a strong alkali as a catalyst

Question 16

what can acyl chlorides react with

Answer 16

water, alcohols, ammonia and primary amines

Question 17

what are the observations of acyl chlorides reacting with nucleophiles and why does it happen

Answer 17

1. colourless fuming gas
2. strong smalling of vinegar due to hydrogen chloride gas

this is due to the acyl chloride reacting with water vapour in the air because they are so reactive

Question 18

how is aspirin manufactured

Answer 18

salicylic acid + ethanoic anhydride/ethanoyl chloride

Question 19

why is ethanoic anhydride used industrially

Answer 19

it is cheaper than ethanoyl chloride and it is also safer as it is less corrosive and reacts more slowly with water so doesn’t produce the dangerous hydrogen chloride fumes

Question 20

how do you hydrolyse oils and fats
what are the products of the reaction

Answer 20

heating them with sodium hydroxide and this is base hydrolysis.

The alcohol formed it a glycerol when the OH- ions react with the oil/fat and the carboxylate ions combine with Na+ ions from the NaOH to form a sodium salt(soap)