Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

chemistry all note flashcards - 3rd And 4th > 4.6 - Chemical tests > Flashcards

4.6 - Chemical tests Flashcards

1
Q

what test is used to test for hydrogen

A

squeaky pop test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the method of the squeaky pop test

A
  1. collect a sample of gas in a tube
  2. attempt to ignite the gas using a lit splint
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the positive result for hydrogen in the squeaky pop test

A

squeaky pop sound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what chemical reaction is taking place during the squeaky pop test

A

the combustion of H2 to form H2O
2H2(g) + O2(g) –> 2H2O(g)
the pop sound is caused by hot gas rushing out of the test tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what test is used to test for oxygen

A

glowing splint test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the method of the glowing splint test

A
  1. collect a sample of gas in a test tube
  2. place a glowing splint into the tube
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the positive result for oxygen in the glowing splint test

A

the splint relights

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the chemical reaction taking place during the glowing splint test

A

the combustion of the wood in the splint
it relights because the pure O2 is more concentrated than the O2 in normal air. this means the wood in the splint combusts faster

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what test is used to test for the presence of H2O

A

copper sulfate test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the method of the copper sulfate test

A
  1. add anhydrous copper sulfate (CuSO4)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the positive result for the presence of H2O

A

the anhydrous copper sulfate changes from white to blue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the test used to test the purity of H2O

A

measure its boiling point and compare it to 100 degrees C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the method of the boiling water test

A
  1. measure its boiling point
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the positive result for the purity of H2O

A

the closer it is to 100 degrees C the more pure it is

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the test used to test for carbon dioxide

A

limewater test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the method of the limewater test

A
  1. bubble a sample of gas through water
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the positive result for carbon dioxide

A

a white precipitate forms - limewater turns cloudy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is the chemical reaction taking place during the limewater test

A

limewater is saturated calcium hydroxide solution, Ca(OH)2
it forms a white precipitate of calcium carbonate (CaCO3) when it reacts with CO2
Ca(OH)2(aq) + CO2(g) –> CaCO3(s) + H2O(l)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the test used to test for chlorine

A

damp blue litmus test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is the method of the damp blue litmus test

A
  1. place damp blue litmus paper in a sample of gas
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the positive result for chlorine

A

the blue litmus turns white - it bleaches

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is the chemical reaction taking place during the damp blue litmus test

A

Cl2 is a good bleaching agent, so it easily removes colour from other substances
in this test it dissolves into the dampness (H2O) and removes the colour from the litmus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is the test used to test ammonia

A

damp red litmus test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is the method of the damp red litmus test

A
  1. place damp red litmus paper in a sample of gas
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is the positive result for ammonia

A

the damp red litmus turns blue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what is the chemical reaction taking place during the damp red litmus test

A

this happens because the NH3 reacts with the dampness (H2O) to form OH- ions
NH3(g) + H2O (l) –> NH4+(aq) + OH-(aq)
the NH3 acts as a base by accepting H+ ions from the H2O
the OH- ions are what’s left after H2O has lost H+, and they are alkaline so the litmus turns blue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what are cations

A

positive ions, like Na+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what cations do I need to know

A

Li+/ Na+/ K+/ Ca 2+/ Cu 2+/Fe 2+/Fe 3+/ NH 4+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what do many metal cations cause a non-luminous (blue) Bunsen flame to do

A

change colour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what can we tell by looking at the colour of the bunsen flame after being in contact with a substance

A

we can tell which metal cation is in the substance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

how do you conduct a flame test

A
  1. dip a piece of nichrome/ platinum wire into hydrochloric acid
    these wires don’t colour the flame, and the acid cleans the wire
  2. dip the wire into a sample of solid or solution
    this causes some of the sample to stick onto the wire
  3. place the tip of the wire into a non-luminous bunsen flame
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what metal cation is involved if the flame colour is red

A

Li+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

what metal cation is involved if the flame colour is yellow

34
Q

what metal cation is involved if the flame colour is lilac

35
Q

what metal cation is involved if the flame colour is orange-red

36
Q

what metal cation is involved if the flame colour is blue-green

37
Q

what is sodium hydroxide used to test for

A

Cu2+/Fe2+/Fe3+

38
Q

if one of Cu2+/Fe2+/Fe3+ is present when sodium hydroxide is added, what is formed

A

a metal hydroxide precipitate

39
Q

how do you conduct a NaOH test

A
  1. dissolve the sample in water
  2. add a few drops of NaOH(aq)
40
Q

what is the precipitate formula if its precipitate colour is blue

41
Q

what is the metal cation involved if its precipitate is blue

42
Q

what colour precipitate does Cu2+ make

43
Q

what is the precipitate formula if its precipitate colour is green

44
Q

what is the metal cation involved if its precipitate is green

45
Q

what colour precipitate does Fe2+ make

46
Q

what is the precipitate formula if its precipitate colour is brown

47
Q

what is the metal cation involved if its precipitate is brown

48
Q

what colour precipitate does Fe3+ make

49
Q

what are the two types of equations you can write for the reaction in a sodium hydroxide test

A

a fully balanced equation
an ionic equation (just shows the formation of the precipitate)

50
Q

what is an example of a fully balanced equation for the metal cation Cu2+

A

CuCl2(aq) + 2NaOH(aq) –> Cu(OH)2(s) + 2NaCl(aq)
sample blue ppt
containing
Cu2+

51
Q

what is an example of an ionic equation for the metal cation Cu2+

A

Cu2+(aq) m+ 2OH-(aq) –> Cu(OH)2(s)

52
Q

what is used to test for ammonium ions

A

using sodium hydroxide

53
Q

what is formed in an ammonia test

54
Q

how is an ammonium test conducted

A
  1. dissolve the sample in water
  2. add some NaOH(aq) and warm it
  3. test the gas evolved with damp red litmus paper
55
Q

in the ammonium test if NH4+ ions are present in the sample what will happen

A

the litmus paper will turn blue

56
Q

how does the ammonium test work

A

because the NH4+ from the sample and OH- ions from the ammonium react to produce NH3(g)

57
Q

what is an equation for the reaction in the ammonium test

A

NH4+(aq) + OH-(aq) –> NH3(g) + H2O(l)
sample test with
containing damp
NH4+ litmus paper

58
Q

what are anions

A

negative ions like O2-

59
Q

what anions do I need to know

A

Cl-/Br-/I-/CO3 2-/SO4 2-

60
Q

what test is used to test for halide ions (Cl- Br- I-)

A

silver nitrate test

61
Q

what are the halide ions

A

Cl-/Br-/I-

62
Q

how is the silver nitrate test conducted

A
  1. dissolve the sample in water
  2. add nitric acid (HNO3)
  3. add silver nitrate (AgNO3) solution
63
Q

in the silver nitrate test if Cl-/Br-/I- ions are present what forms

A

a precipitate with the Ag+ ions from the AgNO3

64
Q

what is the precipitate formula if its precipitate is white

65
Q

what halide ion is involved if the precipitate colour is white

66
Q

what colour precipitate does Cl- make

67
Q

what is the precipitate formula if its precipitate is cream

68
Q

what halide ion is involved if the precipitate colour is cream

69
Q

what colour precipitate does Br- make

70
Q

what is the precipitate formula if its precipitate colour is yellow

71
Q

what halide ion is involved if the precipitate colour is yellow

72
Q

what colour precipitate does I- make

73
Q

how is the carbonate test conducted

A
  1. add hydrochloric acid (HCl), look for effervescence
  2. if there is effervescence, bubble the gas through limewater
74
Q

what happens in the carbonate test if CO3 2- ions were present in the sample

A

the gas evolved turns the limewater coudy

75
Q

what would the reaction equation for the carbonate test look like (using calcium carbonate as the sample)

A

CaCO3(s) + 2HCl(aq) –> CaCl2(aq) + H2O(l) + CO2(g)
sample test using limewater
containing
CO3 2-

76
Q

why is it important to confirm the gas evolved is CO2 using limewater

A

acids also evolve a gas when they react with some other things. checking that the gas is CO2 prevents false positives

77
Q

how is the sulfate test conducted

A
  1. add hydrochloric acid (HCl), look for effervescence
  2. if there’s no effervescence, add barium chloride (BaCl2) solution
78
Q

what happens in the sulfate test if SO4 2- ions are present

A

they will form a white precipitate with Ba2+ ions from the BaCl2

79
Q

what does the equation for the formation of the white precipitate (BaSO4) look like

A

Ba2+(aq) + SO4 2-(aq) –> BaSO4(s)

80
Q

why is it important to add the HCl in step 1 of the sulfate test

A

because carbonate ions also form a white precipitate with Ba2+ ions. by only continuing to step 2 if there’s no effervescence, we can prevent a false positive

chemistry all note flashcards - 3rd And 4th (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions