9.2 Lifestyle Chemistry: Surfactant and Colloid Cleaning Products

Properties of emulsions

•      Emulsions allow oily substances and water to be applied to a surface at the same time

•      The two phases (oil and water) are mixed together using an emulsifier.

•      Emulsifiers are described using a 1-20 scale called the hydrophilic-lipophilic balance (HLB)

•      The lower the HLB, the more less water in the resulting emulsion

Properties of emulsions:

•      Purpose of emulsions Surfactants can emulsify grease into water and can also make water more alkaline which can neutralise acids.

First hand investigations

•      Write experiments to compare different emulsions based on:

a)     Feeling

b)    pH

c)     Conductivity

First hand investigation

Aim: To determine the effect of surfactants on water drops

Equipment:

2 x pipette droppers

2 x measuring cylinder

500mL dishwashing liquid

2L tap water

2 x 250mL beakers

Method:

1.     Pour about 200mL of water into one beaker

2.     In the other beaker, mix 200mL water with 20mL of dishwashing liquid (the exact amounts are not important at this stage)

3.     Using one pipette, put 200 drops of tap water in one measuring cylinder.  Record the volume.

4.     Using the other pipette, put 200 drops of the detergent mixture in the other measuring cylinder.  Record the volume.

5.     Repeat steps 3 – 4 five times and average results.

Results

Discussion

What trend was observe?

Explain this trend.

Conclusion

Did you answer the aim?

What is the trend of your results?