# Separating mixtures

> Use a property the parts don't share


## Objectives

- Explain that a mixture is separated by using a difference in a physical property.
- Describe magnetic separation, separation by surface tension and electric separation.
- State that separating a mixture forms no new substance.

## 1. Separating mixtures: from zero




## 2. Filings in the sand

Predict: what is the quickest way to separate them?

- Pass a magnet over the mixture ✓
- Add water and stir until both dissolve
- Shake the mixture through a sieve

A magnet attracts iron but not sand. The grains are about the same size and neither dissolves in water, so a sieve or water would not separate them.

[ar-EG] الـ magnet بيجذب الـ iron ومش بيجذب الرمل. الحبيبات تقريبًا في نفس الحجم ومفيش حاجة فيهم بتدوب في الميّة، فالمنخل أو الميّة مش هيفصلوهم.
## 3. Magnetic separation

To separate a mixture, use a property its parts don't share. Magnetic separation A magnet attracts the particles that are magnetic. The other particles stay behind. No new substance forms. The iron is still iron, and the sand is still sand.


## 4. Held up by the water's surface

Surface tension The pull between water particles at the surface. It makes the surface act like a thin stretched skin. This skin can hold up some small, light particles. Others sink to the bottom. So the two kinds come apart.


## 5. Electric separation

Some particles take an electric charge more easily than others. A charged plate attracts them, and the rest fall straight down. Match each difference to the method that uses it.


## 6. Choose the method

Two fine powders are mixed. Particles of one powder stay on the water's surface; the other powder sinks. Which method works, and why?

- Pass a magnet over it, because the powders differ in magnetism
- Heat it strongly to turn the sand into something new
- Sprinkle it on water: surface tension holds up one powder and the other sinks ✓

The difference given is how the powders behave on water: surface tension holds up particles of one powder while the other sinks, so separation by surface tension works. No new substance forms.

[ar-EG] الفرق اللي في السؤال هو تصرّف المسحوقين على الميّة: الـ surface tension بيشيل حبيبات مسحوق واحد والتاني بيغطس، فالفصل بالـ surface tension هو اللي ينفع. ومفيش مادة جديدة بتتكوّن.
## 7. Summary

Use a property the parts don't share. No new substance forms. **Magnetic separation**: a magnet attracts the magnetic particles. **Surface tension**: some small particles stay on top; others sink. **Electric separation**: a charged plate attracts some particles. Each method uses a property the parts don't share. No new substance forms. Can you explain why a sieve could not separate the iron filings from the sand in the hook? Next: iron ore is concentrated with these same three methods.



Chapter: Transition Elements (https://yaani.ai/en/learn/chemistry/chem-s3-en.ch1)
Source: https://yaani.ai/en/lesson/chem-s3-en.lesson-chem.mixture-separation