Chemical analysis Flashcards
What is a pure substance?
Something that has nothing added to it, natural state or compound
What happens when boiling a pure mixture?
Pure mixtures have a specific boiling point
Impurities lower the melting point and increase the melting range and boiling points
What is a formulation?
Mixture with an exact amount of components
Made by a ‘recipe’
What is the mobile phase in paper chromatography?
Where molecules can move, the liquid or gas
What is the stationary phase in paper chromatography?
Where molecules can’t move, the solid so paper
What happens to the molecules in paper chromatography?
The molecules constantly switch between the stationary and mobile phase
Chemicals that spend more time in the mobile phase move further
What is the Rf value?
How soluble a substance is
Distance moved by solvent (dot)
What is the test for chlorine gas?
Damp blue litmus paper bleaches red quickly then white
Goes red as chlorine is acidic
What is the test for oxygen?
A glowing splint will relight
What is the test for carbon dioxide?
Carbon dioxide turns limewater cloudy
Whats the test for Hydrogen?
A lit splint will make a pop
Pops as water is formed
What is an anion?
A negatively charged ion
( Think the opposite to PANIC )
The ‘an’ in ANION means un so unpositive or negative
What is a Cation?
A positively charged ion
( Think opposite to PANIC )
The t in CATION looks like a +
CATions are PAWsitive
Examples of Anions
Carbonates
Sulfates
Halides
Examples of Cation:
Lithium Sodium Potassium Calcium Copper
Tests for carbonates?
- Put sample in test tube
- Add drops of dilute acid
- Connect test tube to limewater
- if CO2 is present limewater goes cloudy
Test for sulfates?
Add Hcl and barium chloride to test tube with mystery solution
If sulfate is present a white precipitate forms
Test for Halides?
Add a few drops of nitrate acid and silver nitrate solution to chloride, bromide and iodide
Chloride forms a white precipitate
Bromide forms a cream precipitate
Iodide forms a yellow precipitate
How do we test for cations?
Through flame tests and precipitate tests
Flame tests
Lithium ---> Crimson flame Sodium ---> Yellow flame Potassium ---> Purple flame Calcium ---> Orange red flame Copper ---> Green flame
Precipitate tests?
Many metal hydroxides are insoluble and form a coloured precipitate
Calcium ---> White Copper ---> Blue Iron || ---> Green Iron ||| ---> Brown Aluminium ---> White to colourless Magnesium ---> White
