O Levels Chemistry (Collection and drying of gases)

Hi Jeryl T,

Since you do not know what is your first Chemistry topic in 2013, we shall do some recap on Sec 3 stuff.

Before you proceed further, I want to remind you ( Oh no, Mrs Chew wants to nag again? ) that Chemistry needs to spend some time to memorise the information before you can do A LOT OF questions. 🙂

 

Every week, I shall try to give you something ( I will not give you a lot each time so dont worry!!)  to memorise and I will give you a short worksheet to test your memory+ understanding during class.

I AM VERY SURE , WITH THESE KNOWLEDGE IN YOUR HEAD, YOU CAN DO VERY WELL! I have confidence in you!

 

For you, this week homework is to STUDY and REMEMBER

– Some common gases’ solubility in water

– Some common gases’ density (relative to air)

– Collection of Gases methods

– Some common drying agents for gas

 

Some common gases’ solubility in water

  • More common gases i.e oxygen, carbon dioxide and hydrogen are nearly insoluble in water.
  • More “chim” gases ( those which our young siblings do not know) i.e ammonia, hydrogen chloride and chlorine gases are soluble.

 

Some common gases’ density (relative to air)

  • Hydrogen, Ammonia –> less dense ( you can remember Handsome Admirer Likes Damsel)
  • Carbon dioxide, hydrogen chloride and chlorine gas –> More dense ( you can remember CD, Heavy Cat and Cat sinks in water )
  • Oxygen –> Equally dense

 

Collection of Gases methods

  • Displacement of air – downwards delivery ( Means gas is collected at the bottom, so it is used when gas is denser than air)
  • Displacement of air – upwards delivery ( Means gas is collected at the top, so it is used when gas is less dense than air)

Gas upward delivery

 

 

  • Displacement of water – used when gas is insoluble in water

displacement-of-water

Some common drying agents for gas

  • Concentrated sulfuric acid ( used for acidic gas)
  • Quick lime aka Calcium oxide ( used for alkaline gas i.e ammonia)
  • Fused calcium chloride ( used for general gases like hydrogen and oxygen as it is neutral in nature)

 

I want your commitment to MEMORISE these information hor! 🙂

Watsapp me when you know the topic of Chemistry you are learning at school currently! See ya!

 

 

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