C8: Chemical Analysis (triple) Flashcards
What happens to the melting and boiling point of a pure substance when it becomes impure?
The melting point decreases
The boiling point increases
What is a formulation?
A mixture with exact amounts of components for a specific purpose.
How are different components of a mixture separated using chromatography?
Different molecules have different attractions to the mobile and stationary phases. The more mobile the further it will travel up the paper with the solvent.
What is the Rf value?
The ratio between the distance travelled by the dissolved solid and the distance traveled by the solvent.
Rf =
Distance traveled by substance / distance travelled by solvent
What is the test for chlorine gas?
Damp litmus paper is bleached white
What is the test for oxygen gas?
Relight a glowing splint.
What is the test for carbon dioxide gas?
Lime water goes cloudy when carbon dioxide is bubbled through.
What is the test for hydrogen gas?
Burns with a squeaky pop when in contact with a lit splint.
Describe the colours from a cation flame test of lithium, sodium, potassium, calcium and copper.
lithium crimson sodium yellow potassium lilac calcium orange-red copper green
Describe the colours from a cation precipitate test with NaOH for calcium, copper (II), iron (II), iron (III), aluminium and magnesium.
calcium white copper (II) blue iron (II) green iron (III) brown aluminium white but dissolves in excess NaOH magnesium white
Describe the test for carbonates (anions).
dilute acid. if present, CO2 will form so lime water will go cloudy.
Describe the test for sulphates (anions).
HCl and barium chloride. if present, a white precipitate will form.
Describe the test for halides (anions).
nitric acid and silver nitrate. if present:
chloride white precipitate
bromide cream precipitate
iodide yellow precipitate
