Chemical tests Flashcards
Describe the test for hydrogen gas?
Burnt splint test - hydrogen gas will ignite with a squeaky pop sound
Describe the test for oxygen gas?
A good method to test for oxygen is to take a glowing splint and place it in a sample of gas, if it re-ignites the gas is oxygen.
Describe the test for carbon dioxide?
Carbon dioxide turns lime water cloudy/milky
Describe the test for ammonia gas?
- It will turn moist litmus paper from red to blue.
- Ammonia gas will put out a lit splint
Describe the test for chlorine gas?
The simplest test for chlorine is a litmus paper test, chlorine will turn a damp blue litmus paper red, and then it’ll bleach it white
How do you carry out a flame test?
1-dip a clean wire loop into a solid sample of the compound being tested.
2-put the loop into the edge of the blue flame from a Bunsen burner.
3-observe and record the flame colour produced.
Flame test for Li+
Red
Flame test for Na+
Yellow
Flame test for K+
Lilac
Flame test for Ca2+
Orange-red
Flame test for Cu2+
blue-green
Test for NH4+ ammonia using sodium hydroxide
METHOD:
-Add Aqueous Sodium Hydroxide to the solid or solution and heat using Bunsen burner
-Lower damp red litmus paper into gas produced
RESULT:
If Ammonium ions are present, pungent-smelling gas is produced
Gas produced turns damp red litmus paper Blue
Test for Cu2+
Step 1: some solution is poured in a test tube.
Step 2: A few drops of an aqueous solution of sodium hydroxide (which acts as a reactive) are added.
Step 3: A blue precipitate forms which confirms the presence of copper ions.
Test for Fe2+
Add a few drops of sodium hydroxide solution to the solution. A dirty-green precipitate forms
Test for Fe3+
Add a few drops of sodium hydroxide solution to the solution. A reddish-brown precipitate forms
Test for Chloride, Bromide and Iodide Ions using silver nitrate solution
Add a few drops silver nitrate solution to the solutions containing either Cl, Br or I ions.
Cl - white precipitate
Br - very pale cream precipitate
I - very pale yellow precipitate
Test for SO4-2
The test solution is acidified using a few drops of dilute hydrochloric acid, and then a few drops of barium chloride solution are added. A white precipitate of barium sulfate forms if sulfate ions are present.
Test for C03-2
Carbonate ions, CO3 2- are detected using a dilute acid . Bubbles are given off when an acid, usually dilute hydrochloric acid, is added to the test compound . The bubbles are caused by carbon dioxide. Limewater is used to confirm that the gas is carbon dioxide.
Describe the test for the presence of water using anhydrous copper(II) sulfate
The white solid turns blue in the presence of water
Describe a physical test to show whether a sample of water is pure
If the sample is pure water it will boil at 100 degrees
