Revision Class (Acid and Alkaline & Layers of Atmosphere)

​Acid and Alkali

Layers of Atmosphere​

Revision​

Litmus Indicator

​

Acid: Red

Alkaline: Blue​

​

pH indicator​

Multiple Choice

Vinegar is a solution of ethanoic acid, what is the colour formed when a few drops of litmus indicator is added into it?

• Red

• Yellow

• Blue

• Green

Methyl orange​

​

Acid: Red

Neutral: Orange

Alkali: Yellow​

pH indicator​

phenolphthalein

​

​Acid: Colourless

Neutral: Colourless

Alkaline: Pink​

pH indicator​

Multiple Choice

A few drops of phenolphthalein is added into a conical flask filled with sodium hydroxide, the solution will turn

• colourless

• pink

• blue

• green

Universal indicator can be used to determine the approximate pH value of solution. ​

​Universal indicator

​Layers of Atmosphere

Scientist divided the atmosphere into 5 layers based on altitude, temperature and pressure.​

Open Ended

What are the 5 layers of atmosphere?

Troposphere​

• Complicated weather conditions

• Densest layer, highest air pressure​

Atmosphere | Chemistry

Stratosphere​

• Clear weather, high visibility, suitable for commercial plane flight.

• It has ozone layer to protect the Earth from harmful ultraviolet rays.

Atmosphere | Chemistry

Mesosphere​

• Coldest layer.

• Protects the Earth from meteoroids.

Atmosphere | Chemistry

Thermosphere​

• Hottest layer

• Ionosphere

• Used for distance communication

• Auroras

Atmosphere | Chemistry

Exosphere​

• Lowest density and lowest air pressure

• Contains hydrogen and inert helium gas

Atmosphere | Chemistry