Flame Tests Flashcards
Test for hydrogen
Test tube of hydrogen gas
Hold a lighted splint at the open end of the test tube
Lighted splint pops
Wear eye protection, hydrogen is flammable
How to get hydrogen to test
Zinc and dilute sulfuric acid
Test for oxygen
15cm3 of hydrogen peroxide solution in a small comical flask
Add manganese IV oxide from the end of the spatula
Insert a glowing splint (made by blowing out a lighted splint) in the mouth of the flask
Glowing splint will relight in oxygen
Safety wear eye protection
Test for carbon dioxide
Bubble carbon dioxide through limewater
Limewater turns cloudy
What is calcium hydroxide solution
Limewater
Test for chlorine
Damp blue litmus paper turns white when bleached with chlorine
How to carry out a flame test
A Nichrome wire loop dipped in hydrochloric acid then heated to sterilise
Then it should be dipped in the acid again before testing the metal
Hold the loop in the roaring blue flame of a Bunsen burner
Use the colour of the flame to identify the metal ion
If the sample is mixed then some colours can be masked
Cation test conditions
Sodium hydroxide
Aluminium 3+ sodium hydroxide
White precipitate
Calcium 2+ sodium hydroxide
White precipitate
Magnésium 2+ sodium hydroxide
White precipitate
What happens when you add excess sodium hydroxide to aluminium 3+
Aluminium ions dissolve
After the sodium hydroxide test how do you then distinguish between calcium and magnesium
Flame test
Copper 11 sodium hydroxide
Blue precipitate
Iron 11 sodium hydroxide
Green precipitate
Iron 111 sodium hydroxide
Brown precipitate
Lithium Li+ flame test
Crimson
Sodium, Na+ flame test
Yellow
Potassium, K+ flame test
Lilac
Calcium, Ca2+ flame test
Orange-red
Copper, Cu2+
Green
Carbonate test
Add a dilute acid to a carbonate, it fizzes and produces carbon dioxide gas
Halides test
Dilute nitric acid then silver nitrate
Iodide I- halide test
Yellow precipitate
Bromide ions Br- halide test
Cream precipitate
Chloride Cl- ions halide test
White precipitate
How to test for sulfates
Adding dilute hydrochloric acid followed by barium chloride
Dilute hydrochloric acid first to remove carbonate ions that would form a precipitate with the barium ions
Sulfate result barium chloride test
White precipitate
