Chemical Analysis (Paper 2) Flashcards
What colour flame do lithium ions produce?
Crimson
What colour flame do sodium ions produce?
Yellow
What colour flame do potassium ions produce?
Lilac
What colour flame do calcium ions produce?
Orange - Red
What colour flame do copper ions produce?
Green
What colour precipitate do calcium ions produce?
White
What colour precipitate do copper ions produce?
Blue
What colour precipitate do iron(II) ions produce?
Green
What colour precipitate do iron(III) ions produce?
Brown
What colour precipitate do aluminum ions produce?
White at first but redissolves in excess NaOH to form a colourless solution
What colour precipitate do magnesium ions produce?
White
How do you test for chlorine gas?
Put damp litmus paper near / in the gas. If it bleaches, the gas is chlorine
How do you test for oxygen gas?
Put a glowing splint near / in the gas. If it relights, the gas is oxygen
How do you test for carbon dioxide gas?
Bubble the gas through limewater, if the limewater turns cloudy, the gas is carbon dioxide
How do you test for hydrogen gas?
Put the gas near an open flame, if you hear a squeaky pop, the gas is hydrogen
Define a pure substance
something that only contains one element or compound throughout
Define formulations
mixtures created by humans with a specific purpose and specific amounts of each compound / element in them
Define the mobile phase in chromatography
where the molecules can move. this is always a liquid or gas
Define the stationary phase in chromatography
where the molecules can’t move. this can be a solid or a really thick liquid
Define the Rf value in chromatography
the ratio between the distance travelled by the dissolved substance and the distance travelled by the solvent
What is the equation for calculating the Rf value in chromatography?
distance travelled by substance / distance travelled by solvent
What is the method for flame emission spectroscopy?
- sample is placed in flame
- light released passes through spectroscope which detects light wavelengths to produce a line spectrum
What is the purpose for flame emission spectroscopy?
to identify different metal ions in solutions accurately and find their concentrations
How can flame emission spectroscopy identify different metal ions?
the combination of wavelengths emitted by an ion depends on its charge and electron arrangement so each ion has an individual combination of wavelengths. therefore each ion produces a unique line spectrum
