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Chemistry > Chemical Analysis > Flashcards

Chemical Analysis Flashcards

1
Q

what is a pure substance

A

only one element or compound

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2
Q

how can you test that a substance is pure

A

test melting point. An impurity will higher or lower melting point and increase boiling range

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3
Q

what are formulations with examples

A

useful mixtures with a precised purpose

paint
solvents
binders
fuels
cosmetics 
fertilizers 
metal alloys
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4
Q

why are formulations useful for medicines

A

so goes to the right party of the body at the right concentration and has the right shelf life

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5
Q

what is the mobile phase of chromatography

A

the solvent that moves through the paper

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6
Q

what is the stationary phase of chromatography

A

its the paper. so the mobile phase moves through the stationary phase and carry s anything dissolved in it

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7
Q

what determines how long a solute will stay in the mobile stage of chromatography

A

how soluble they are

how attracted they are to the paper

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8
Q

what is the Rf value

A

distance traveled by the substance / distance traveled by the solvent

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9
Q

test for chlorine

A

turns damp litmus paper white

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10
Q

test for oxygen

A

relights glowing splint

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11
Q

test for hydrogen

A

squeaky pop by lit splint

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12
Q

test for carbon dioxide

A

turns lime water cloudy

cloudiness is calcium carbonate

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13
Q

flame test for metal ions

A 
lithium - crimson
potassium - lilac
calcium - orange 
copper - green 
sodium - yellow
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14
Q

precipitation formed when sodium hydroxide is added to metal ions

A 
calcium - white
copper -  blue
iron II - green
iron III - brown
aluminum - white to colourless
magnesium -  white
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15
Q

how would you test for carbonate ions (negative)

A

add an acid to solution and it will fizzle. Bubble the gas through the lime water. Should turn cloudy

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16
Q

how do you test for halide ions (negative)

A

add nitric acid followed by silver nitrate solution

chloride - white precipitate
bromide - cream
iodide - yellow

17
Q

how do you test for sulfate ions (negative)

A

add HCI and then barium chloride solution

white precipitate

18
Q

why do you add HCI when testing for sulfate ions

A

to react any carbonate ions which would also produce a white precipitate when reacted with barium chloride

19
Q

how does flame emission spectroscopy work

A

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.

20
Q

how can you tell the concentration of the ion in a solution using a line spectrum

A

the intensity of spectrum

21
Q

advantages of flame emission spectroscopy

A

very sensitive
very fast
very accurate

Chemistry (15 decks)

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