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Ss1 Chem Summer WK 3

This document discusses methods for collecting and identifying gases. There are three main methods for collecting gases depending on the gas's density and solubility in water: 1) using a gas syringe, 2) upward/downward delivery if less/more dense than air, 3) over water if not soluble. Key gases that can be collected by each method are provided. Tests are described to identify gases like hydrogen, oxygen, carbon dioxide, chlorine, and ammonia by observing their reactions with items like burning splints and litmus paper. Links are provided to video demonstrations of these collection and identification techniques. Students are assigned an identification activity using clues about gas properties and reactions.

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153 views4 pages

Ss1 Chem Summer WK 3

This document discusses methods for collecting and identifying gases. There are three main methods for collecting gases depending on the gas's density and solubility in water: 1) using a gas syringe, 2) upward/downward delivery if less/more dense than air, 3) over water if not soluble. Key gases that can be collected by each method are provided. Tests are described to identify gases like hydrogen, oxygen, carbon dioxide, chlorine, and ammonia by observing their reactions with items like burning splints and litmus paper. Links are provided to video demonstrations of these collection and identification techniques. Students are assigned an identification activity using clues about gas properties and reactions.

Uploaded by

sulaiman mohammed
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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OLASUPO K.

WEEK 3

CHEMISRTY

SS 1

METHODS OF GAS COLLECTION AND IDENTIFICATION

The method used to collect a particular gas depends on


1) Is the gas more or less dense than air?
2) Is the gas soluble in water?

All gases can be collected using a gas syringe.

If a gas is less dense than air it can be collected by upward delivery or downward displacement
of air. Examples of gases that can be collected using this method are: Hydrogen (H2) and
Ammonia (NH3).

If a gas is denser than air it can be collected by downward delivery or upward displacement of
air. Examples of gases that can be collected using this method are: Carbon dioxide (CO2),
Hydrogen chloride (HCl) and Sulphur dioxide (SO2).

If a gas is not soluble (or only slightly soluble) in water it can be collected over water. Examples
of gases that can be collected using this method are: Oxygen (O2), Hydrogen sulphide (H2S) and
Carbon dioxide (CO2).

Collecting gas with a gas syringe


Collecting gas over water

Collecting gas by upward and downward delivery

The following links contain video clips that explain the methods.

https://youtu.be/sawiD_gwU7Q

https://youtu.be/xL_A4u0HpSA

Identifying Gases

Test for hydrogen [H2]


Use a burning splint held at the open end of a test tube of gas. Hydrogen burns rapidly with a
squeaky pop sound.
Test for oxygen [O2]
The test for oxygen uses a glowing splint inserted into a test tube of the gas. The splint relights in
oxygen.
Test for carbon dioxide [CO2]
When carbon dioxide is shaken with or bubbled through limewater (An aqueous solution of
calcium hydroxide), the limewater turns cloudy.
Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l)
Test for chlorine [Cl2]
When damp litmus paper is put into chlorine gas, the litmus paper is bleached and turns white.
Test for Ammonia [NH3]
When damp litmus paper is put into ammonia gas, the gas dissolves and the Litmus paper
goes blue.

The following links contains video clips that explain the methods.

https://youtu.be/_GqBl83Koig

https://youtu.be/ExOJWcQ7uRQ

The table below gives a summary of the methods

Assignment

Use the clue to identify the mystery gas:


1. When a burning splint is placed near the opening of a test tube containing this gas, a popping
sound occurs.
2. A glowing splint will reignite when placed in a test tube of this gas.
3. When moist litmus paper is placed in a test tube of this gas, it turns red.
4. A colourless gas which forms explosive mixture with air, and the only product of combustion
is a gas which turns lime water milky.
5. Ammonium salt when treated with alkali, and given some heat liberates a gas, which gives
dense white fumes with HCl.
6. A colourless gas having a suffocating odour, such that it decolourises acidified potassium
permanganate solution.

PLEASE SEND YOUR ANSWERS TO THE EMAIL ADDRESS GIVEN BELOW:


abdulqadrola@mail.com

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