U3 - Cleaning materials

Question 1

Def: Hydrophillic

Answer 1

substance that mixes with water or dissolves in water

Question 2

Describe the structure of the soap molecule

Answer 2

• head contains O2 atoms and is polar, mixes with water, hydrophillic
• tail contains C and H atoms and is non-polar, dissolves in oil droplets, hydrophobic

Question 3

Def: Emulsifying agent

Answer 3

substance soluble in water and fat and enables fat to be dispersed in the water

Question 4

Def: Emulsion

Answer 4

mixture of 2 liq that are not usually able to mix

Question 5

Def: Emulsifier

Answer 5

substance that stabilizes an emulsion

Question 6

How does soap act as an emulsifying agent

Answer 6

it enables fat to be uniformly dispersed in water as an emulsion. soap causes fat and water to mix easily. when fat mixed with water solution, soap molecules squeeze between water molecules and fat molecules. soap acts as an emulsifier.

Question 7

How are substances able to mix

Answer 7

Substances will only mix if they have similar structures and bonding

Question 8

Can sugar and salt dissolve in petrol

Answer 8

sugar is a molecular solid, and will dissolve in petrol that is a molecular liquid. Salt is an ionic solid, and will not dissolve in petrol.

Question 8

Can sugar and salt dissolve in petrol

Answer 8

sugar is a molecular solid, and will dissolve in petrol that is a molecular liquid. Salt is an ionic solid, and will not dissolve in petrol.

Question 9

Can sugar and salt dissolve in petrol

Answer 9

sugar is a molecular solid, and will dissolve in petrol that is a molecular liquid. Salt is an ionic solid, and will not dissolve in petrol.

Question 10

Describe the structure of a soap (detergent) molecules

Answer 10

soap has hydrocarbon tail that mixes with oils and fats and is hydrophobic. the head is the ionic part that dissolves in water and is hydrophillic. The head therefore easily mixes with water, while the tail part easily mixes with oils and fats

Question 11

Def: Surfactants

Answer 11

substances that reduce the surface tension of a liquid when it is dissolved in water, soap is a surfactant

Question 12

Explain how surfactants work

Answer 12

hydrophobic chain is forced out of the water in between the water molecules, while the ionic head remains in the water.

Question 13

How is soap made

Answer 13

made from fat or oil (plant or animal) together with an alkali.

Question 14

How are detergents made

Answer 14

made from crude oil sources together with and alkali

Question 15

Is soap biodegradable or non-biodegradable

Answer 15

biodegradable

Question 16

Is detergents biodegradable or non-biodegradable

Answer 16

non-biodegradable

Question 17

What are the effects of non-biodegradable detergents

Answer 17

should be avoided because they are persistant, and can influence the environment negatively. Cause pollution

Question 18

Advantages of the use of soap and detergents

Answer 18

• Remove fat an oil from clothes
• Soap makes water “wetter
• Prevent the formation of “scum” when used in hard water

Question 19

Disadvantages of the use of soap and detergents

Answer 19

• Non-biodegradable detergents cause environmental pollution
• Scum on the surface of the water affects clothes

Question 20

How are soaps prepared

Answer 20

are prepared by the hydrolysis of fats or oils. The fat/oil is hydrolysed, by adding sodium hydroxide to the fat.

Question 21

Def: Hydrolysis

Answer 21

breaking down a compound by a chemical reaction with water.

Question 22

Preparation of soaps

Answer 22

• heat some oil / fats
• add some methanol and mix well
• add concentrated sodium hydroxide
• warm gently until thick
• heat salt solution till boiling point and add to soap mixture
• heat strongly to evaporate off liquid, pour into molds + allow to cool

Question 23

What is the formula for the preparation of soap

Answer 23

fat + sodium hydroxide — soap + glycerol