Chemical Analysis Flashcards
what is a pure substance
only one element or compound
how can you test that a substance is pure
test melting point. An impurity will higher or lower melting point and increase boiling range
what are formulations with examples
useful mixtures with a precised purpose
paint solvents binders fuels cosmetics fertilizers metal alloys
why are formulations useful for medicines
so goes to the right party of the body at the right concentration and has the right shelf life
what is the mobile phase of chromatography
the solvent that moves through the paper
what is the stationary phase of chromatography
its the paper. so the mobile phase moves through the stationary phase and carry s anything dissolved in it
what determines how long a solute will stay in the mobile stage of chromatography
how soluble they are
how attracted they are to the paper
what is the Rf value
distance traveled by the substance / distance traveled by the solvent
test for chlorine
turns damp litmus paper white
test for oxygen
relights glowing splint
test for hydrogen
squeaky pop by lit splint
test for carbon dioxide
turns lime water cloudy
cloudiness is calcium carbonate
flame test for metal ions
lithium - crimson potassium - lilac calcium - orange copper - green sodium - yellow
precipitation formed when sodium hydroxide is added to metal ions
calcium - white copper - blue iron II - green iron III - brown aluminum - white to colourless magnesium - white
how would you test for carbonate ions (negative)
add an acid to solution and it will fizzle. Bubble the gas through the lime water. Should turn cloudy
how do you test for halide ions (negative)
add nitric acid followed by silver nitrate solution
chloride - white precipitate
bromide - cream
iodide - yellow
how do you test for sulfate ions (negative)
add HCI and then barium chloride solution
white precipitate
why do you add HCI when testing for sulfate ions
to react any carbonate ions which would also produce a white precipitate when reacted with barium chloride
how does flame emission spectroscopy work
sample is placed in a flame. Electrons get exited and move up an energy level. When they drop back down they transfer energy as light. This light is passed through a spectroscope which can defer different wavelengths of light to produce a line spectrum. Different ions emit different wavelengths of light so will produce a different line spectrum.
how can you tell the concentration of the ion in a solution using a line spectrum
the intensity of spectrum
advantages of flame emission spectroscopy
very sensitive
very fast
very accurate
