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Organic Chemistry Lab > Module 1: QUALITATIVE ANALYSIS OF ELEMENTS IN ORGANIC COMPOUNDS > Flashcards

Module 1: QUALITATIVE ANALYSIS OF ELEMENTS IN ORGANIC COMPOUNDS Flashcards

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1
Q

the elements that can be commonly found among organic compounds include

A

C - chlorine
H - hydrogen
O - oxygen
N - nitrogen
S - sulfur
P - phosphorus
Si - silicon

F - fluorine
Cl - chlorine
Br - bromine
I - iodine

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2
Q
  • “systemic approach” that can give satisfactory results in identifying elements in organic compounds using qualitative chemical reagents
A

Qualitative Analysis

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2
Q

CO2 is detected by __________, while the H2O is detected by anhydrous cupric sulfate

A

lime water

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3
Q

approach with the use of organs/senses (except hearing)

A

organoleptic approach

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3
Q

upon heating, the carbon and hydrogen present in the organic compound are oxidized to ________________________

A

carbon dioxide and water

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3
Q

CO2 reacts with Ca(OH)2 forming

A

CaCO3 and H2O

CO2 + Ca(OH)2 → CaCO3 + H2O

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4
Q

these elements must be converted first into inorganic ions before proceeding to qualitative analysis → done by fusing the organic compound with the __________

A

sodium metal

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4
Q
  • qualitative chemical tests highly rely on “organoleptic approach” through observation of test results
A

Qualitative Analysis

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5
Q

REACTION WITH CUPRIC OXIDE

  • detected by strongly heating the said substance with _____________
A

cupric oxide (CuO)

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5
Q

CO2 is detected by lime water, while the H2O is detected by ______________________

A

anhydrous cupric sulfate

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6
Q

other elements such as “nitrogen, halogens, and sulfur” are “difficult to detect” in an organic compound → they __________ in solution and are “bonded covalently”

A

do not ionize

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6
Q

CO2 reacts with Ca(OH)2 forming CaCO3 and H2O, wherein the _____________________ due to the formation of precipitates (CaCO3)

A

clear solution becomes turbid

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6
Q
  • H2O reacts with anhydrous CuSO4 forming CuSO4 * 5 H2O, wherein the _______________ (CuSO4 * 5 H2O)
A

white powder turns to blue

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7
Q

H2O reacts with anhydrous CuSO4 forming

A

CuSO4 * 5 H2O

5 H2O + CuSO4 → CuSO4 * 5 H2O

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8
Q

the alkaline solution obtained by extracting the fused mass in water is called _____________

A

sodium extract or Lassaigne’s extract

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9
Q
  • the following reactions are created upon the fusion of the said elements with sodium metal:

S + 2 Na → ?

A

Na2S

! aside from Lassaigne’s sodium fusion test, there are other applicable qualitative tests that can be used

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9
Q
  • the following reactions are created upon the fusion of the said elements with sodium metal:

C + N + Na →

A

NaCN

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10
Q
  • the following reactions are created upon the fusion of the said elements with sodium metal:

X (Cl, Br, I) + Na → ?

A

NaX (X = Cl, Br, I)
sodium halide

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11
Q

SODA LIME TEST FOR AMIDE NITROGEN

  • if the organic compound is in the form of ___________________, heating it with _________ (NaOHand CaO) will liberate ________________ gas (characteristic pungent ammonia odor)
A
  1. amino nitrogen (–NH2)
  2. soda lime
  3. ammonia (NH3)
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12
Q

SODA LIME TEST FOR AMIDE NITROGEN

  • to confirm the presence of the said gas, a moist ________________________
A

red litmus paper must turn to blue

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13
Q

SODA LIME TEST FOR AMIDE NITROGEN

  • the reaction involved:

urea + NaOH + CaO → ??

A

2 NH3 + Na2CO3

Note:
urea + NaOH + CaO → 2 NH3 + Na2CO3

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14
Q

______________is limited to organic compounds with amino (–NH2) group only, nitro (-NO2) and azo (-N=N-) compounds cannot be detected by this test

A

soda lime test

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15
Q

soda lime test is limited to organic compounds with _____________ , nitro (-NO2) and azo (-N=N-) compounds cannot be detected by this test

A

= amino (–NH2) group only

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16
Q

Test for Halogens

A
  1. BEILSTEIN TEST
  2. SILVER NITRATE TEST
17
Q
  • an organic halogen compound dipped in a copper wire will yield (what color of flame when burned?)
A

green-colored flame

18
Q

What elements are Halogens

A

fluorine
chlorine
bromine
iodine

19
Q
  • the copper oxide from the “copper wire” formed upon heating, reacts with the halogen from the organic compound to form __________ which is responsible the color of the flame
A

cupric halide

20
Q

_____________ does not yield a positive result (cupric fluoride is not volatile)

A

fluorine

21
Q

SILVER NITRATE TEST

  • the halogen reacts with silver nitrate in the
    presence of ______________ forming insoluble silver halide
A

dilute nitric acid

22
Q

SILVER NITRATE TEST

  • the halogen reacts with silver nitrate in the
    presence of dilute nitric acid forming ______________
A

insoluble silver halide

23
Q

SILVER NITRATE TEST

  • the silver halide yields a (what precipitate?) ________________, confirming the presence of a halogen
A

white to light yellow precipitate

23
Q

R-X + AgNO3 + HNO3 → ??

A

AgCl

24
Q

Test for nitrogen

A

Soda lime test

25
Q

Test for Sulfur

A

LEAD ACETATE TEST

26
Q

LEAD ACETATE TEST

  • the organic compound containing sulfur will yield ____________ upon reaction with lead acetate
A

lead sulfide

27
Q

LEAD ACETATE TEST

  • the presence of sulfur is identified by the production of (what color of precipitate?) _____________ through lead acetate test
A

brownish-black precipitate

28
Q

_____________ contains the amino acid cysteine

A

albumin

29
Q

albumin contains the amino acid _________
(an amino acid with sulfhydryl group)

A

cysteine

30
Q
  • in strongly basic solution, cysteine will react
    to lead ions (Pb2+) forming (what precipitate?) ________________
A

black precipitate,
PbS

31
Q
  • __________ the solution causes the breaking of the polypeptide chain
A

heating

32
Q

NaOH → Na+ + OH–

2 Na+ + S → Na2S → 2 Na+ + S2–

S2– + Pb2+ → PbS

A

LEAD ACETATE TEST
* chemical reaction involved

33
Q

Test for oxygen

A

FERROX TEST

34
Q

FERROX TEST
* oxygen can be detected using ________________

A

ferrox paper or iron (III) hexathiocyanatoferrate

35
Q

FERROX TEST
* iron (III) ammonium sulfate reacts with potassium thiocyanate to form iron (III) hexathiocyanatoferrate

A

take note

36
Q

FERROX TEST
* this compound dissolves in the presence of oxygen giving off (what color?) _______________ of the solution

A

red to reddish-purple color

37
Q

_____________ is prepared by soaking a filter paper in methanol with equal parts of ferric chloride and ammonium thiocyanate

A

ferrox paper

38
Q

the complex FeSCN2+ yields a (what solution color?) ______________ as it is distributed through the filter paper and the organic compound containing oxygen

A

deep red colored solution

39
Q

CARBON & HYDROGEN
= Reaction with lime water

A

clear solution turns turbid

40
Q

CARBON & HYDROGEN
= Reaction with anhydrous cupric sulfate

A

white powder turns blue

41
Q

NITROGEN
= Soda lime test

A

characteristic pungent odor, red litmus turns blue

42
Q

HALOGENS
= Beilstein test

A

green-colored flame

43
Q

SULFUR
= Lead acetate test

A

formation of black precipitate

44
Q

HALOGENS
= Silver nitrate test

A

formation of white precipitate

45
Q

OXYGEN
= Ferrox test

A

turns to red to reddish-purple solution

46
Q

Ca(OH)2 is _______

A

lime water

47
Q

“nitrogen, halogens, and sulfur” must be converted first into inorganic ions before
qualitative analysis

(True or False)

How is it done?

A

True

: this is done by fusing the organic
compound with the sodium metal

48
Q

NaOH and CaO is ________

A

soda lime

49
Q

Cannot be detected by soda lime test

A

= nitro (-NO2)
= azo (-N=N-) compounds

50
Q

iron (III) ammonium sulfate +
potassium thiocyanate =??

A

iron (III) hexathiocyanatoferrate

Organic Chemistry Lab (6 decks)

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