4.6 Analysis Flashcards
Gas test for hydrogen
Lit splint —> squeaky pop
Gas test for oxygen
Glowing splint relights
Gas test for carbon dioxide
Bubble through limewater
Turns cloudy
Gas test for chlorine
Damp blue litmus paper
Turns white
Gas test for ammonia
Damp red litmus paper
Turns blue
Testing for the presence of water
Anhydrous copper sulphate
Turns from white to blue
Testing the purity of water
Measure boiling point
Compare to 100 degrees Celsius
Closer to 100 degrees Celsius = more pure
What are cations
Positive ions
How to conduct a flame test
Dip a piece of nichrome/platinum wire into hydrochloric acid
Dip the wire into a sample of solid or solution
Place tip of wire into a non-luminous Bunsen flame
Lithium (Li+) flame test colour
Red
Sodium (Na+) flame test colour
Yellow
Potassium (K+) flame test colour
Lilac
Calcium (Ca2+) flame test colour
Orange-red
Copper (Cu2+) flame test colour
Blue-green
Which flame test cations do you need to know results of
Lithium (Li+)
Sodium (Na+)
Potassium (K+)
Calcium (Ca2+)
Copper (Cu2+)
What does sodium hydroxide test for
Cu2+
Fe2+
Fe3+
NH4+
How to conduct a sodium hydroxide test
Dissolve sample in water
Add a few drops of sodium hydroxide (NaOH aq)
Cu2+ sodium hydroxide test results
Blue precipitate
Precipitate has the formula Cu(OH)2
Fe2+ sodium hydroxide test results
Green precipitate
Precipitate has the formula Fe(OH)2
Fe3+ sodium hydroxide test results
Brown precipitate
Precipitate has the formula Fe(OH)3
Ammonium (NH4+) sodium hydroxide test method
Dissolve sample in water
Add NaOH (aq) and warm it
Test the gas with damp red litmus paper (ammonia test)
If present, litmus paper turns blue
What are anions
Negative ions
Testing for halides (anions) - (Cl-, Br-, I-) method - silver nitrate test
- Dissolve sample in water
- Add nitric acid (HNO3)
- Add silver nitrate (AgNO3) solution
Halide anions to use the silver nitrate test for
Cl-
Br-
I-
