Chemical tests Flashcards
How do you test for hydrogen?
collect gas and place lit splint near, Squeaky pop test
How do you test for oxygen?
collect gas and it will relight a smoldering splint
How do you test for carbon dioxide?
limewater goes cloudy or extinguishes a lit splint (usually use limewater test as is unique)
How do you test for chlorine?
damp blue litmus paper bleaches
How do you test for a double carbon bond?
Bromine water turns colourless
How do you carry out a flame test?
- 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.
What is the flame colour of potassium?
lilac
What is the flame colour of strontium?
red
What is the flame colour of calcium?
orange-red
What is the flame colour of sodium?
yellow
What is the flame colour of barium?
apple green
What is the flame colour of copper?
blue-green
What is the flame colour of magnesium?
white
What is the flame colour of aluminium?
grey-white
What colour precipitate do chloride ions form?
white
What colour precipitate do bromide ions form?
cream
What colour precipitate do iodide ions form?
yellow
How do you carry out the test for sulfate ions?
- Add dilute hydrochloric acid to sample. 2. Add barium chloride solution. 3. If sulfate ions are present we will see a white precipitate.
How do you carry out the test for halide ions?
- Add dilute nitric acid to the sample. 2. Add dilute silver nitrate solution. 3. Halide ions produce a precipitate of the silver halide.
How do you carry out the test for carbonate ions?
- Add dilute acid to the sample. 2. The acid will react to produce carbon dioxide gas, you will see effervescence. 3. Bubble the gas throughout lime water which will turn cloudy.
Sodium hydroxide test for aluminium?
white precipitate, dissolves in excess
Sodium hydroxide test for magnesium?
white precipitate
Sodium hydroxide test for calcium?
white precipitate
Sodium hydroxide test for copper II?
light blue precipitate
Sodium hydroxide test for iron II?
light green to brown precipitate
Sodium hydroxide test for iron III?
reddish-brown precipitate
How do you determine a pure substance?
pure substances have sharp melting points, mixtures melt over a range of temperatures.
What is a formulation?
a useful mixture, with exact measurements.
Name an accurate method of analysing the substances of a mixture?
flame emission spectroscopy
What is meant by pure?
a substance that consists of only one type of element or only one compound.
