Colloids and Emulsions

Colloids and Emulsions

Refresher

​Solution: A mixture where one substance dissolves in another, like salt in water.

Suspension: A mixture where large particles are dispersed in a liquid or gas but eventually settle to the bottom, like sand in water.

What do the particles look like?

​Solution	​Suspension
​	​

What do the particles look like?

Categorize

Options (8)

Particles are very small and not visible

Particles are large and visible

Particles do not dissolve and settle over time

Can be separated by filtration

Example: Muddy water

Particles dissolve completely and don’t settle

Cannot be separated by filtration

Example: Saltwater

Sort the characteristics into their correct mixture type.

Solutions

Suspensions

Poll

Is a mixture only a suspension if it is a solid in a liquid?

• Yes

• No

​​Parkes 2020

Sydney 2009

Dropdown

Examine the "recipe", then select the correct words to make the sentences true.



If they are put in the same container and left without shaking, oil and vinegar ​

Select answer

​ .



If shaken, the vinegar ​

Select answer

mixed through the oil.



If left standing, vinaigrette ​

Select answer

into its parts.



Vinaigrette ​is a type of ​

Select answer

.

Colloids

A colloid is a mixture where they particles are too big to dissolve like in a solution but too small to settle and separate like in a suspension.

The particles are big enough to reflect light so the mixture ends up looking cloudy.

Draw a small table in your books to show the particles of a colloid.

Colloids
​

Multiple Choice

In a colloid, the particles are:

• Larger than in a suspension

• Too small to see but large enough to scatter light

• Completely dissolved

• Too small to scatter light

Multiple Choice

Which of the following is an example of a colloid?

• Sugar water

• Muddy water

• Fog

• Vinegar

Multiple Choice

Colloids are:

• Cloudy

• Transparent

Milk

• Milk contains fats and water

• Over time, milk straight from a cow will separate into two liquid layers (fat and water)...making it a??

• Why doesn't that happen to the milk in our fridges?
  

Particles are evenly spread out, e.g. a solution

​​Homogenous

Particles are clumped or uneven, e.g. a suspension

Heterogenous

Milk is homogenised for a number of reasons:

Homogenised Milk

• Increase shelf-life

• Possible to mix milk from different cows

• No unappealing layer and better colour

• Easier for the body to digest

Raw milk is passed through a valve under high pressure. The fat globules are squeezed and broken up into smaller droplets. Because of their small size, these droplets stay in suspension. It becomes a colloid.

​

Multiple Choice

Homogenisation is a process that removes cream from milk.

• True

• False

​All of these things have something in common. They are a type of colloid called an emulsion. What do you think the common thing is?

Select the correct definition:

Emulsions:

1. Mixtures where small particles of one substance are dissolved in another.

2. Homogeneous mixtures where two gases are combined to form a stable mixture.

3. A type of colloid where tiny droplets of one liquid are dispersed in another liquid.

Select the correct definition:

Emulsions:

1. Mixtures where small particles of one substance are dissolved in another.

2. Homogeneous mixtures where two gases are combined to form a stable mixture.

3. A type of colloid where tiny droplets of one liquid are dispersed in another liquid.

Poll

If you leave an emulsion for a long time will the parts separate?

• Yes

• No