Aerosols and pressure. What's in an aerosol?

1. What are aerosols?

What's in an aerosol?

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	Aerosol sprays
		An aerosol is any fine spray that hangs in the air. However, when we talk about consumer ‘aerosols’, we mean a product in a pressurised container.

Aerosol cans

Picture 1.1 An aerosol can.

Aerosol cans are under pressure. Never puncture a real can or try to look inside

		Let's have a look inside an aerosol can. This is what it contains. 1. The product. This is a solution or suspension of the substance that we want to spray. 2. The propellant. It is the propellant that produces the pressure inside the can. 3. The actuator. When you press down on the actuator, it opens ... 4. ... the valve and allows the product to be pushed out. 5. The dip tube. The dip tube goes down to the bottom of the can to make sure it is always dipped in the product and that you always get all of the product out.

	Propellants
		There are two types of propellant. They are: a pressurised gas (such as nitrogen) a liquified gas whose vapour collects above the liquid and pushes down. There are advantages and disadvantages to each type (see page 12). However, liquefied gas propellants have two jobs.

	Liquefied gas propellants
		As well as forcing the product out of the can, liquified gas propellants help to give the spray a texture or break it up into small droplets. As the liquid propellant leaves the nozzle, it starts to evaporate. In the case of a foam, the gas produced at the nozzle forms bubbles within the product and makes it frothy. In the case of a body spray, the evaporating propellant helps to break the product up into tiny droplets.

Question 1
Look at the paragraph below. There are some words missing. In each case, choose the best word from the drop down list. Then click on the 'Show answers' button to see how well you did.
There are two main types of propellant. They are both a at room temperature and pressure. The propellants push the out of the can. The stops the liquid escaping until you press the . Also, a gas propellant helps give the aerosol its texture.

Summary Close

an aerosol is a fine spray suspended in the air
the spray is forced out of a can by the propellant
the propellant also gives the spray its texture