Chemical analysis Flashcards
In chemistry, what is a pure substance?
Something made of only one type of substance
What is the difference between the melting and boiling points of a pure and impure substance?
Pure - sharp/one specific temp
Impure - Broad/occurs across a range of temps
What is a formulation?
A mixture designed for a specific purpose
What are some examples of formulations?
Fuels, cleaning agents, paints, medicines, alloys, fertilisers, food
What is chromatography?
A process for separating coloured mixtures
How is Rf calculated?
Rf = distance moved by substance
__________________________
distance moved by solvent
What is the test for hydrogen?
Lit splint gives squeaky pop
What is the test for oxygen?
Re-lights a glowing splint
What is the test for carbon dioxide?
Turns limewater milky if bubbled through it
What is the test for chlorine?
Bleaches damp litmus paper
What is the test for aluminium, calcium and magnesium ions?
Forms white precipitate with sodium hydroxide solution
How can aluminium ions be distinguished from calcium and magnesium ones?
The white precipitate will dissolve with excess sodium hydroxide
What colour precipitates are formed when sodium hydroxide solution is added to solutions of copper, iron(II) and iron(III) ions?
Copper - blue precipitate
Iron (II) - green precipitate
Iron(III) - brown precipitate
What is the test for a halide ion?
Add silver nitrate and nitric acid: chloride forms white precipitate, bromide forms cream precipitate, iodide forms yellow precipitate
What is the test for a carbonate ion?
Carbon dioxide gas formed on addition of acid
What is the test for a sulfate ion?
White precipitate formed with hydrochloric acid and barium chloride
What colours are produced by different metals in a flame test?
Lithium - crimson Sodium - yellow Potassium - lilac Calcium - orange-red Copper - green
What is instrumental analysis?
Using complex scientific equipment to identify substances
What are the three advantages of instrumental analysis?
Rapid
Accurate
Sensitive
What information does flame emission spectroscopy produce?
The wavelength of light given off by a metal in a flame to identify the metal and its concentration
