Chemical tests Flashcards
How do you test for ammonia?
Hold damp red litmus paper near the mouth of the test tube, the litmus paper will turn blue if ammonia is present.
How do you test for carbon dioxide?
Bubble the gas through limewater and if carbon dioxide is present the limewater will turn cloudy.
How do you test for Chlorine?
If chlorine gas is present, damp blue litmus paper will turn red and then be bleached white
It turns red initially as acids are produced when chlorine comes into contact with water
How do you test for hydrogen gas?
Hold a burning splint at the mouth of a test tube and you will hear a squeaky pop if hydrogen is present
How do you test for oxygen?
Hold a glowing splint at the mouth of a test tube and the splint will relight if oxygen is present.
How do you carry out a flame test?
- Dip the loop of an unreactive metal wire such as nichrome or platinum in diliute acid
- Hold it in the blue flame of a bunsen burner until there is no colour change
-Dip the loop into the solid sample/ solution and place it in the edge of the blue bunsen flame
in a flame test, why is it important to place the wire into acid first before placing it in a sample.
to prevent contamination
-not doing this might result in two or more ions being present on the wire meaning the colours will mix
-one colour could mask another and you would not be able to tell which ion it is
what metal ion is present in a red flame?
Li+
what colour flame does Li+ produce?
red
What metal ion is present in a yellow flame?
Na+
What metal ion is present in a lilac flame?
K+
What colour flame does K+ produce?
lilac
what colour flame does Na+ produce?
Yellow
What colour flame does Ca^2+ produce?
orange-red
What colour flame does Cu^2+ produce
blue-green
What metal ion is present in a blue-green flame?
Cu^2+
what ion is present in an orange-red?
Ca^2+
