Chemical Analysis Flashcards
What is a pure substance?
A pure substance is a single element, or compound, not mixed with any other substance
What is a formulation and how is it made? Give examples
- A formulation is a mixture of compounds in measured quantities that has been designed as a useful product
- Formulations include fuels, cleaning agent, paints, medicines, Alloys, fertilisers, and foods
- e.g. Alloys are mixtures of metals; they are harder than pure metals, so have a particular purpose.
Describe paper chromatography
A) a start line is drawn at the bottom of the paper. The mixture is spotted on the line.
B) a beaker is filled with small amount of solvent (it cannot touch or go above the start line)
C) paper is hung on a rod and placed in a beaker
D) solvent travels up the paper, plus separating the components
E) before solvent level reaches the end, the paper is taken out, and the finish line is marked. The paper is dried.
F) procedure works when different compounds have different affinities for the solvent/paper
G) paper is called the stationary phase – it doesn’t move.
Solvent is the mobile phase
How is Rf calculated?
Distance moved by the spot/distance moved by solvent
Describe the test for hydrogen, oxygen, carbon dioxide and chlorine
Hydrogen- pop with burning splint over gas
Oxygen - glowing splint, relights
Carbon dioxide - turns limewater milky
Chlorine - bleaches damp litmus paper and makes it white
Describe the flame test results
Lithium compounds- crimson red flame
Sodium compounds - yellow flame
Potassium compounds - lilac flame
Calcium compounds - orange, red flame
Copper compounds - green flame
What are instrumental methods?
They are accurate, sensitive and rapid methods which are useful when the amount of sample is very small
What are cations and anions?
Cations are the positive ions; and ions are the negative ions
