Chemical analysis Flashcards

1
Q

what is everyday purity?

A

-nothing added to it e.g beeswax

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2
Q

what is chemical purity?

A

-only contains one element or compound

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3
Q

how to test purity of sample?

A
  • have specific m/bpts
  • compare with m/bpts in data book

closer measured value to actual, purer the sample

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4
Q

what do impurities do to samples?

A

-lower mpt and increase range

increase bpt and increase range

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5
Q

what are formulations?

A
  • useful mixture with precise purpose made by formula
  • measured quantities of components contributes to properties so it meets function
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6
Q

paints are formulations composed of:

A
  • pigment: colour e.g titanium oxide in white paints
  • solvent: dissolve components and alter viscosity
  • binder: forms film holds pigment in place after painted on
  • additives: further change physical and chemical properties
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7
Q

how are formulation important in pharmaceutical industry

A
  • alter formulation of pill so delivers to right body part
  • right conc
  • consumbale
  • long shelf life
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8
Q

info on composition is found on labels

A
  • ratio or percentage of each component
  • choose formulation with right composistion of particular use
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9
Q

what is a mobile phase?

A

-molecules can move in liquid or gas

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10
Q

what is a stationary phase?

A

molecules can’t move in solid or real thick liquid

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11
Q

what effects how quick chemical moves or how spots are formed?

A
  • distribution: more time in m than s moves further up paper
  • spots form if chemicals spend diff time in m
  • no. of spots depend on solvent
  • pure substance forms one spot in any solvent
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12
Q

amount of time molecules spend in each phase depends on?

A
  • solubility of solvent
  • how attracted to paper
  • higher solubility and less attraction means longer in m
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13
Q

what is the Rf value and its calculation?

A
  • ratio between distance travelled by solute and solvent
  • distance by solute/distance by solvent
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14
Q

how to test for chlorine?

A
  • bleaches damp litmus paper white
  • red for a sec cuz acidic
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15
Q

how to test for oxygen?

A

glowing splint inside test tube and will relight

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16
Q

how to test for CO2

A

bubble it thru aquaeous solution of limewater, turns cloudy

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17
Q

how to test for hydrogen?

A

hold lit splint at end of test tueb and get squeaky pop

18
Q

how to test for carbonates?

A
  • add drops of dilute HCl with pipette
  • connect to test tube of limewater
  • if ions present then limewater cloudy
19
Q

how to test for sulfates?

A
  • add drops of HCl then barium chloride solution to test tube
  • if ions present white barium sulfate precipitate form
20
Q

how to test for halides?

A
  • add drops of dilute nitric acid then drops of silver nitrate solution
  • white precipitate silver chloride
  • cream precipitate of silver bromide
  • iodide precipitate of silver iodide
21
Q

compounds of some metals burn with…

A

characteristic flame

22
Q

Lithium burns with

A

crimson flame

23
Q

sodium burns with

A

yellow flame

24
Q

potassium burns with

A

lilac flame

25
Q

calcium burns with

A

orange-red flame

26
Q

copper burns with

A

green flame

27
Q

how to carry out a flame test?

A
  1. clean platinum wire loop in dilute HCl
  2. hold in blue flame from bunsen until burns colourless
  3. dip loop into sample and into flame and record colour
    4.
28
Q

what a flame tests used for?

A
  • identify different metal ions
  • only works for sample with single cation
  • if contains mixture, flame colours of some ions hidden by others
29
Q

how to test for cations in compounds?

A
  • many metal hydroxides insoluble and precipitate out of solution
  • add drops of sodium hydroxide to get coloured insoluble hydroxide
30
Q

calcium and OH gives what precipitate?

A

white

31
Q

copper and OH gives what precipitate?

A

blue

32
Q

iron (II) and calcium gives what precipitate?

A

green

33
Q

iron (III) and calcium gives what precipitate?

A

brown

34
Q

aluminium and calcium gives what precipitate?

A

white at first but redissolves in excess NaOH to form colourless solution

35
Q

magnesium and calcium gives what precipitate?

A

white

36
Q

how to carry out flame emission spectroscopy?

A
  1. place sample in flame to heat ions and energise electrons
  2. dropped energy levels transfer energy as light
  3. passes thru spectroscope to detect diff wavelengths of light to make line spectrum
37
Q

what does combination of wavelengths emmited by an ion depend on?

A
  • charge and electron arrangement
  • diff ions emit diff wavelengths of light
  • so has diff pattern and line spectrum
38
Q

what does intensity of spectrum indicate?

A

-conc of that ion in solution

39
Q

what are line spectrums used for?

A
  • identify ions in solution
  • calculate their concentration
40
Q

what are advantages of using machines compared to conducting test?

A
  • very sensitive
  • very fast
  • very accurate