Chemical Analysis Flashcards
What are the main features of a pure substance
It only contains one element or compound
Has exact melting and boiling point
What does impurities do to the melting and boiling points of a pure substance
They lower the melting point and increase the boiling point
What is a formulation
A mixture of substances where each component decides the mixtures overall properties
If the substance in paper chromatography travels far, what does that mean
It is strongly attracted to the mobile phase
If the substance in paper chromatography doesn’t move far what does that mean
It is strongly attracted to the stationary phase
What is the method of paper chromatography
Make pencil line and add drops of substance on line
Dip bottom of paper into solvent
Solvent travels up paper and picks up substances being tested and carries them up paper
Components that travel furthest are highly soluble and are minimally attracted to chromatography paper
This produces a chromatogram
How do you work out the Rf value
Distance travelled by substance divided by distance travelled by solvent
What is the test for hydrogen
Lit splint squeaky pop
Why does the hydrogen pop test occur
Hydrogen burns rapidly in presence of oxygen
What is the test for oxygen
Glowing splint relights
What is the test for carbon dioxide
Bubble through limewater and turns cloudy
What is the test for chlorine gas
Bleaches Damp litmus paper
What does a lilac flame show in the flame test
Potassium ions present
What does yellow flame mean in the flame tests
Sodium ions are present
What does and orange red flame mean in the flame tests
Calcium ions are present
What does a green flame mean in the flame test
Copper ions present
What does a crimson flame mean in the flame tests
Lithium ions present
What is the method for flame test
Clean wire loop in HCl
Dip loop in sample
Hold loop in blue flame of Bunsen
Record colour
How do you test for metal hydroxide
Add substance to sodium hydroxide (NaOH) and colour of precipitate shows what metal hydroxide was formed
That then shows what metal ions were in substance
If you get a white precipitate when adding NaOH to an unknown substance what metal ions could be present
Calcium
Aluminium
Magnesium
If you get a brown precipitate when adding NaOH to an unknown substance what metal ions is present
Iron III
If you get a blue precipitate when adding NaOH to an unknown substance what metal ions is present
Copper II
If you get a green precipitate when adding NaOH to an unknown substance what metal ions is present
Iron II
How do you test for carbonates in an unknown solution
Carbonates react with dilute acid to form salt co2 and h2o
Use standard gas test to work out if carbonate is present as it will produce co2
