CHAPTER 3 – MECHANICAL MIXTURES

Grade 7 SciencePresented on: February 17,

2011

Minds On

3.2 – Separating Mechanical Mixtures

SORTINGDEFINITION

Involves looking at various pieces and physically moving one or more of the pieces into different containers

This allows similar pieces to be put together

EXAMPLES

PizzaSaladLaundry

FLOATINGDEFINITION

Lighter component rises to the top of a liquid where it can be skimmed off

EXAMPLES

Melted chicken fat

SETTLINGDEFINITION

Heavier component sinks to the bottom of a liquid – the liquid can be poured off leaving the heavier component

EXAMPLES

Gold dustWaste water treatment

Blood

A device that is used by many labs is a CENTRIFUGE It is an equipment piece that holds

test tubes The test tubes are spun very quickly

causing the heavier component to sink quickly to the bottom

Device that can be used for Settling

CENTRIFUGE

MAGNETDEFINITION

Some metals and alloys (iron,steel) are attracted to magnets. If they are part of a mixture we can remove them using a magnet.

EXAMPLES

Scrap Metal Yard

A device that is used when there is a mixture with solid and liquid parts

This device has many visible holes that allow smaller solid pieces and liquids to pass through blocking large solid pieces

Device that can be used

SIEVE

SIEVINGDEFINITION

Process in which larger pieces of matter are separated out of the mechanical mixture

EXAMPLES

Pasta in Water using a colander

A device that is used to separate solids from liquids

This device has many small holes that trap solid pieces of a mixture but allow liquids and gases to pass through.

Device that can be used

FILTER

FILTRATIONDEFINITION

Mixture passes through a filter to separate solid pieces from a liquid or gas

EXAMPLES

Pepper in Water

1. You will be working in groups – each group will have a letter

2. Each group will get two cups, salt/pepper mixture, filter paper

3. Each group member will have a role – number yourselves 1 to 4.

4. Group Member One: Will go to the side and grab one cup with their group letter which has 50mL of water.

5. Students will grab a small cup with salt/pepper mixture6. Group Member Two: Will mix the mixture and the water

using a popsicle stick7. Group will work together to try and separate the mixture.

EXPERIMENT