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(GCSE) Chemistry > C12. Chemical Analysis (Y11 - Spring 2) > Flashcards

C12. Chemical Analysis (Y11 - Spring 2) Flashcards

1
Q

🟠 (Identifying Gases)

What is the Test and Positive Observation for CO2 (g)

A

Test:
Bubble through limewater (Ca(OH)

Positive Observation:
Limewater turns milky (cloudy white)

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2
Q

🟠 (Identifying Gases)

What is the Test and Positive Observation for H2 (g)

A

Test:
Lighted Splint

Positive Observation:
A lighted splint ‘pops’

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3
Q

🟠 (Identifying Gases)

What is the Test and Positive Observation for Cl2 (g)

A

Test:
Damp Indicator Paper

Positive Observation:
Damp blue paper turns white (as it gets bleached

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4
Q

🟠 (Identifying Gases)

What is the Test and Positive Observation for O2 (g)

A

Test:
Glowing Splint

Positive Observation:
A glowing splint relights

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5
Q

🟠 (Identifying Negative Ions)

What is the Test and Positive Observation for Carbonate (CO3^-2)

A

Test:
React with dilute acid to produce carbon dioxide gas which will be put in limewater.

Positive Observation:
Limewater turns milky

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6
Q

🟠 (Identifying Negative Ions)

What is the Test and Positive Observation for a Halide

  • Chloride, Cl^-
  • Bromide, Br^-
  • Iodide, I^-
A

Test:
React the halides with a silver nitrate solution

Positive Observation:
React with silver nitrate solution to produce a precipitate.

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7
Q

🟠 (Identifying Negative Ions)

What is the Test and Positive Observation for Sulphate (SO4^2-)

A

Test:
Add barium chloride to the sulphate ions

Positive Observation:
Forms a white precipitate when barium chloride is added

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8
Q

🟠 What is the Flame Test for Identifying Positive Ions

A

Clean a nichrome wire by dipping in a concentrated HCl and holding in a roaring Bunsen Burner

Dip the clean wire into the concentrated HCl (aq) and into the sample. Hold in the roaring blue flame and observe the colour

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9
Q

🟠 What is the Sodium Hydroxide Test for Identifying Positive Ions

A

Add NaOH (aq) dropwide to 1cm^3 of the aqueous ion in excess.

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10
Q

🟠 (Identifying Positive Ions)

What is the Test and Positive Observation for Lithium, Li^+

A

Test:
Flame Test - Hold in the roaring blue flame and observe the colour
(See full flame test)

Positive Observation:
Red Flame

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11
Q

🟠 (Identifying Positive Ions)

What is the Test and Positive Observation for Sodium, Na^+

A

Test:
Flame Test - Hold in the roaring blue flame and observe the colour
(See full flame test)

Positive Observation:
Yellow Flame

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12
Q

🟠 (Identifying Positive Ions)

What is the Test and Positive Observation for Potassium, K^+

A

Test:
Flame Test - Hold in the roaring blue flame and observe the colour
(See full flame test)

Positive Observation:
Blue Flame

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13
Q

🟠 (Identifying Positive Ions)

What is the Test and Positive Observation for Calcium, Ca^2+

A

Test:
Flame Test - Hold in the roaring blue flame and observe the colour
(See full flame test)

Positive Observation:
Orange Flame

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14
Q

🟠 (Identifying Positive Ions)

What is the Test and Positive Observation for Copper, Cu^2+

A

Test:
Flame Test - Hold in the roaring blue flame and observe the colour
(See full flame test)

Positive Observation:
Light Blue Flame

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15
Q

🟠 (Identifying Positive Ions)

What is the Test and Positive Observation for Calcium, Ca^2+

A

Test:
Sodium Hydroxide Test - Add NaOH (aq) dropwide to 1cm^3 of aqueous solution
(See full NaOH test)

Positive Observation:
White Precipitate

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16
Q

🟠 (Identifying Positive Ions)

What is the Test and Positive Observation for Magnesium, Mg^2+

A

Test:
Sodium Hydroxide Test - Add NaOH (aq) dropwide to 1cm^3 of aqueous solution
(See full NaOH test)

Positive Observation:
White Precipitate

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17
Q

🟠 (Identifying Positive Ions)

What is the Test and Positive Observation for Aluminium, Al^3+

A

Test:
Sodium Hydroxide Test - Add NaOH (aq) dropwide to 1cm^3 of aqueous solution
(See full NaOH test)

Positive Observation:
Silver Precipitate

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18
Q

🟠 (Identifying Positive Ions)

What is the Test and Positive Observation for Iron (II), Fe^2+

A

Test:
Sodium Hydroxide Test - Add NaOH (aq) dropwide to 1cm^3 of aqueous solution
(See full NaOH test)

Positive Observation:
Green Precipitate

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19
Q

🟠 (Identifying Positive Ions)

What is the Test and Positive Observation for Iron (III), Fe^3+

A

Test:
Sodium Hydroxide Test - Add NaOH (aq) dropwide to 1cm^3 of aqueous solution
(See full NaOH test)

Positive Observation:
Orange Precipitate

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20
Q

🟠 (Identifying Positive Ions)

What is the Test and Positive Observation for Copper (II), Cu^2+

A

Test:
Sodium Hydroxide Test - Add NaOH (aq) dropwide to 1cm^3 of aqueous solution
(See full NaOH test)

Positive Observation:
Blue Precipitate

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21
Q

🟠 Advantages of using Chemical Tests for Identifying Substances

A
  • It’s cheaper
  • No training needed
  • It is quicker
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22
Q

🟠 Disdvantages of using Chemical Tests for Identifying Substances

A
  • Difficult to detect in small amounts/Not very sensitive
  • Destructive
  • Not quantitative
  • Limited to certain substance
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23
Q

🟠 Advantages of using Modern Instrumental Methods for identifying substances

A
  • Accurate and sensitive (can detect small amounts)
  • Small amounts can be used
  • It’s quantitative
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24
Q

🟠 Disadvantages of using Modern Instrumental Methods for identifying substances

A
  • Equipment is very expensive
  • Extensive training needed
  • You need something to compare the data to
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25
Q

🟠 What are Instrumental Analytical techniques used for nowadays

A

Instrumental analytical techniques are now used in forensic science to investigate crime scenes. They are also used by environmental agencies to monitor pollution, in the steel and water industries and in medicine to monitor the condition of hip and knee joints.

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26
Q

🟠 Describe the difference between a continuous spectrum and a line spectrum

A

The continuous spectrum shows all the wavelengths of light) and the line spectrum is specific, as it only shows specific wavelengths of light.

27
Q

🟠 Explain how flame emission spectroscopy is used to identify what metal ions are present in a sample.

A

Each type of flame gives off a different set lines which can then be compared to various different other ions.

28
Q

🟠 What other information can be obtained from a flame emission spectrum?

A

The concentration if the invidiual ions, which is relative to the intensity of the lines

29
Q

🟠 Explain why a simple flame test could not be used to identify which two ions were present in the mixture of two metal ions

A

In flame tests, you can only see one colour in a flame, not multiple. Some flame colours end up masking over other flame colours.

30
Q

🟠 Which element was discovered in the sun using emission spectroscopy

A

Helium

31
Q

🟠 Why flame emission spectroscopy is used in the steel industry

A

Steel is a mixture of iron, and has a small amount of chromium and manganeese, and flame emission spectroscopy checks the composition of the steel, to see if it matches up with what’s expected.

32
Q

🟠 Why flame emission spectroscopy is used by water companies

A

To check the concentration of mineral ions in the water.

33
Q

🟠 What compounds are used to make the following coloured fireworks:

  • bright red
  • blue
  • green/blue
  • orange/red
  • yellow/orange
A

Bright Red:
Strontium (Strontium Carbonate)

Blue:
Copper (Copper Chloride)

Green/Blue:
Barium (Barium Chloride)

Orange/Red:
Calcium (Calcium Chloride)

Yellow/Orange:
Sodium (Sodium Chloride)

34
Q

🟠 Explain why it is difficult to distinguish sodium ions and calcium ions in flame tests

A

It’s difficult to distinguish between them due to the fact that both flames are of a similar colour.

35
Q

🟠 Some tests were carried out on ionic substance C. Bubbles of gas were given off when hydrochloric acid was added to a sample of C. An orange-yellow flame was seen in a flame test.

a) Identify the positive ion in substance C
b) Identify the negative ion in substance C
c) Give the formula of substance C

A

a) Fe^3+
b) SO4^2-
c) Fe2(SO4)3

d)
Name: Iron (III) Hydroxide
Ionic Equation: Fe^3 (aq) + 3 OH^- (aq) —> Fe(OH)3 (s)

e)
Name: Barium Sulphate
Ionic Equation: Ba^2+ (aq) + SO4^2- (aq) —> BaSO4 (s)

36
Q

Some tests were carried out on ionic substance C. Bubbles of gas were given off when hydrochloric acid was added to a sample of C. An orange-yellow flame was seen in a flame test.

a) Identify the positive ion in substance C
b) Identify the negative ion in substance C
c) Give the formula of substance C

A

a) Na^2+
b) CO3^2-
c) Na2CO3

37
Q

🟠 Some tests were carried out on ionic substance E. Addition of sodium hydroxide solution to a solution of E gave a green precipitate. Addition of acidified barium chloride solution to a solution of E gave a white precipitate.

a) Identify the positive ion in substance E
b) Identify the negative ion in substance E
c) Give the formula of substance E
d) Name the green precipitate and give an ionic equation for its formation
e) Name the white precipitate and give an ionic equation for its formation

A

a) Fe^2+
b) SO4^2-
c) FeSO4

d)
Name: Iron (II) Hydroxide
Ionic Equation: Fe^2+ (aq) + 2OH^- (aq) —> Fe(OH)2 (s)

e)
Name: Barium Sulphate
Ionic Equation: Ba^2+ (aq) + SO4^2- —> BaSO4 (s)

38
Q

🟠 How can mixtures be separated

A

Mixtures can be separated by PHYSICAL PROCESSES which DO NOT involve chemical reactions and NO new substances are made.

(By using physical means to achieve the separation, using techniques like:

  • Filtration
  • Crystalisation
  • Distillation
  • Chromatography)
39
Q

🟠 Filtration:

  • Equipment Needed
  • What is it used to separate
  • How it works
A 
Equipment Needed:
- Filter Paper
- Funnel
-Conical Flask
(Leaves Residue and Filtrate)

What is it used to separate:
Separates soild substances mixed with liquid substances.

How it works:
The liquid passes through the filter paper, but the solid doesn’t, as the solid particles are too big to fit through the small holes in the filter paper.

40
Q

🟠 Crystallisation:

  • Equipment Needed
  • What is it used to separate
  • How it works
A

Equipment Needed:

  • Bunsen Burner
  • Water Bath
  • Tripod
  • Heatproof Mat
  • Water
  • Solution

What is it used to separate:
Separates a liquid and a soluble solid.

How it works:
The solution is placed in an evaporating basin, before it is heated by a bunsen burner. The liquid will be boiled away.

41
Q

🟠 Simple Distillation:

  • Equipment/Parts Needed
  • What is it used to separate
  • How it works
A

Equipment/ Parts Needed:

  • Thermometer
  • Water Out
  • Water
  • Water In
  • Solution
  • Liquid

What is it used to separate:
Separates a solvent from a solute

How it works:
Liquid is boiled away, but caught and condenses and drops out into the beaker.

42
Q

🟠 Fractional Distillation:

  • Equipment/Parts Needed
  • What is it used to separate
  • How it works
A

Equipment/ Parts Needed:

  • Thermometer
  • Water Out
  • Water
  • Ice
  • Water In
  • Solution
  • Liquid

What is it used to separate:
It it is used to separate different liquids of similar boiling points

How it works:
The flask is heated so that one of the liquids boils, where it then condenses and drops out into the beaker.

43
Q

🟠 How do you tell the difference between a pure substance and a mixture

A

A pure substance melts/boils at a specific temperature

A mixture melts/boils over a range of temperatures

44
Q

🟠 What is a Formulation

A

A formulation is a mixture made up of definite proportions that has been designed as a useful product

45
Q

🟠 How are Formulations made

A

Formulations are made by mixing the components in carefully measured quantities to ensure that the product has the required properties.

46
Q

🟠 What products are all examples of formulations

A
  • Fuels
  • Alloys
  • Fertilisers
  • Pesticides
  • Cosmetics
  • Food Products
47
Q

🟠 How do impurities affect the melting point of a substance and affect the boiling point of a substance

A

Impurities tend to lower the melting point of a substance and raise its boiling point. The size of the difference from the fixed point of a pure substance depends on the amount of any impurities mixed with it.

48
Q

🟠 What is a pure substance

A

A pure substance is ine that is made up of just one substance. That substance can be either an element or a compound.

49
Q

🟠 What are an element or compund’s fixed points?

A

The melting and boiling points of an element or a compound are called its fixed points.

50
Q

🟠 Common formulations are paints. In general, what do paints contain

A
  • A pigment, to provide colour
  • A binder, to help the paint attach itself to an object and to form a protective film when dry.
  • A solvent, to help the pigment and binder spread well during painting by thinning them out.
51
Q

🟠 Common formulations are cleaning agents. In general, what do washing-up liquids contain

A
  • A surfactant, the actual detergent that removes the grease
  • Water, to thin out the mixture so it can squirt more easily from the bottle
  • Colouring and fragrence additives, to improve the appeal of the product to potential customers
  • Rinse agent, to help water drain off crockery.
52
Q

🟠 What happens in Simple Distillation

A

In simple distillation, a solution is heated and boiled to evaporate the solvent. The vapour given off then enters a condenser. This jd an outer glass tube with water flowing through it that acts as a cooling ‘jacket’ around the inner glass tube from the flask. Here, the hot vapour is cooled and condensed back into liquid for collection in a recieving vessel. Any dissolved liquids will remain in the heated flask.

53
Q

🟠 Many people would say that spring water is pure. Is this a pure substance? Explain your answer

A

Spring water is not a pure substance, as it will contain a mixture of substances mixed in with it, so it is not pure.

54
Q

🟠 What is Chromatography used for

A

Chromatography can be used to separate mixtures AND can give information to help identify substances.

55
Q

🟠 What 2 stages does Chromatography show (+ examples of them)

A

Chromatography involves:

  • A stationary phase (chromatography paper)
  • A mobile phase (solvent e.g. water or ethanol)
56
Q

🟠 Where is the Base Line and Solvent Front in a Chromatogram

A

The base line is at the bottom of the chromatogram where the botches of ink are placed

The Solvent Front is at the top of the chromatogram where none of the solvent travels above

57
Q

🟠 What does the Separation on a Chromatogram show

A

Separation depends on the distribution of substances between the phases.

58
Q

🟠 What is the Equation to find the Retention Factor on a Chromatogram

A

Rf = Distance moved by substance / distance moved by solvent

59
Q

🟠 Why is the starting line drawn in pencil on a Chromatogram?

A

The Iine is drawn in penicl, as pencil as it is insoluble (won’t dissolve) and affect the results because of this as it will won’t run.

60
Q

🟠 Why is the level of the solvent in the beaker below the sample line in chromatography?

A

The level of the solvent is below the sample line because the samples would dissolve into the beaker instead of up the paper.

61
Q

🟠 What is the stationary phase and the mobile phase in an experiment including:

  • Filter Paper
  • Starting Line
  • Solvent Front
  • The Solvent
A

Stationary Phase:
- The filter paper

Mobile Phase:
- The solvent

62
Q

🟠 Explain, by referring to the stationary and mobile phases, why the samples move at different speeds during the experiment.

A

Different substances have a different relative attraction/affinity for the mobile and stationary phases; and a substance with a stronger relative attraction to the mobile phase than the stationary phase moves faster than one with a weaker relative attraction to the mobile phase than the stationary phase.

63
Q

🟠 Calculate the Rf value for a sample where:

  • There is 3cm between the startng line and the dot
  • There is 6.7cm between the ethanol and solvent front
A

3/6.7 = 0.45

64
Q

🟠 Explain, by referring to the stationary and mobile phases, why a sample (in which ethanol was compared to that in water) has different Rf values in different solvents

A

Substance 1 has a stronger relative attraction to water compared to the apper than it does for ethanol compared to the paper.

(GCSE) Chemistry (24 decks)

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