Organic Chemistry Lesson 10 Aiming for 4

C10 Organic reactions – Aiming for Grade 4

Aims

In this activity you will find out about functional groups. You will also name and draw some alcohol, carboxylic acid, and ester molecules.

Learning outcomes

After completing this activity, you should be able to:

·  name and draw alcohols, carboxylic acids, and esters

·  describe some characteristics of alcohols, carboxylic acids, and esters.

Task

Complete the activities below.

1  Functional groups are parts of molecules that give the molecule certain characteristics.

This table shows the atoms and bonds that are present in different functional groups.

Type of molecule / Functional group found in the molecule
alkene / C=C
alcohol / O—H
carboxylic acid /
ester /

Look at the displayed formula of the molecules below. Use the information in the table to decide what type of molecule they are.

a 

______(1 mark)

b 

______(1 mark)

c 

______(1 mark)

d 

______(1 mark)

2  On the displayed formulae shown in Question 1, use a highlighter or coloured pencil to highlight the part of each molecule that is the functional group. (4 marks)

3  The following molecules are only partially drawn. Draw in the missing functional group, or atoms to complete each molecule.

a 

methyl methanoate, an ester (1 mark)

b 

propanoic acid, a carboxylic acid (1 mark)

c 

methanol, an alcohol (1 mark)

d 

ethene, an alkene (1 mark)

4  The tables below contain information on how to name organic molecules. The number of carbons decides the start of a molecule’s name. The type of functional group decides the ending of a molecule’s name.

Number of carbons / Start of
molecule name / Functional group present / Ending of molecule name
1 / meth / alkene / -ene
2 / eth / alcohol / -anol
3 / prop / carboxylic acid / -anoic acid
4 / but
5 / pent

Use this information to name the following molecules:

a  A carboxylic acid with three carbon atoms: ______(1 mark)

b  An alkene with two carbon atoms: ______(1 mark)

c  An alkene with five carbon atoms: ______(1 mark)

d  An alcohol with four carbon atoms: ______(1 mark)

e  An alcohol with two carbon atoms: ______(1 mark)

f  A carboxylic acid with five carbon atoms:______(1 mark)

5  Draw lines to link the following boxes up, to correctly describe what alkenes, alcohols, and carboxylic acids are like and how they react. (3 marks)

Alkenes / Dissolve in water and can be biofuels / React with sodium to form a sodium salt and hydrogen gas
Alcohols / Can be made by cracking alkanes / React with alcohols to form fragrant molecules called esters
Carboxylic acids / Form acidic solutions when they dissolve in water / React with steam to form alcohols