Chemical Analysis Flashcards
What is a pure substance?
A substance containing a single element or compound (that is not mixed with another substance)
What is an impure substance?
A substance containing more than one type of element or compound in a mixture.
How do you calculate the Rf value?
Distance moved by substance / distanced moved by solvent
What numbers will the Rf value always be between?
0 and 1
In chromatography, what is shown by how far the substance moves up the paper?
Higher up = more soluble
In chromatography, what does it mean if a substance produces only one spot?
It is pure
In chromatography, why must the line be drawn in pencil?
Pen would dissolve and travel up the paper
What is the test for hydrogen?
Hold a lit splint near gas.
Positive = squeaky pop sound
What is the test for oxygen?
Hold glowing splint near gas.
Positive = splint relights
What is the test for carbon dioxide?
Bubble gas through limewater.
Positive = limewater turns cloudy
What is the test for chlorine?
Hold piece of damp litmus paper near gas.
Positive = litmus paper bleached white
How do you test for aluminium ions?
Slow addition of excess sodium hydroxide solution
Positive = white precipitate that eventually dissolves.
How do you test for calcium ions?
Addition of excess sodium hydroxide solution
Positive = white precipitate that does not dissolve.
How do you test for magnesium ions?
Addition of excess sodium hydroxide solution
Positive = white precipitate that does not dissolve.
How do you test for copper (II) ions?
Add sodium hydroxide solution
Positive = blue precipitate
How do you test for iron (II) ions?
Add sodium hydroxide solution
Positive = green precipitate
How do you test for iron (III) ions?
Add sodium hydroxide solution
Positive = brown precipitate
How do you test for carbonate anions?
Add dilute acid
Positive = CO2 gas formed
How do you test for chloride anions?
Add silver nitrate solution in presence of nitric acid
Positive = white precipitate formed
How do you test for bromide anions?
Add silver nitrate solution in presence of nitric acid
Positive = cream precipitate formed
How do you test for iodide anions?
Add silver nitrate solution in presence of nitric acid
Positive = yellow precipitate formed
How do you test for sulfate anions?
Add barium chloride solution in presence of hydrochloric acid
Positive = white precipitate formed
Flame tests: what is the positive result for lithium?
Crimson
Flame tests: what is the positive result for sodium?
yellow
Flame tests: what is the positive result for potassium?
Lilac
Flame tests: what is the positive result for calcium?
Orange-red
Flame tests: what is the positive result for copper?
Green
What is instrumental analysis?
Using complex scientific equipment to identify substances.
What are 3 advantages of instrumental analysis?
Quick, accurate, sensitive
What information does flame emission spectroscopy produce?
The wavelength of light given off by metal in a flame
To identity of the metal and its concentration
