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chemistry > c12- chemical analysis > Flashcards

c12- chemical analysis Flashcards

1
Q

what is chromatography?

A

a technique that separates mixtures of substances with different levels of solubility

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2
Q

molecule

A

two or more atoms chemically joined

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3
Q

compound

A

two or more different atoms that are chemically joined

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4
Q

solvent

A

the substance that the solute is dissolved in

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5
Q

solute

A

what is dissolved in the solvent

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6
Q

solution

A

mixture of solvent and solute

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7
Q

mobile phase

A

​gas or liquid that carries the component - moves with the sample

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8
Q

stationary phase

A

the part of the apparatus that does not move with the sample

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9
Q

why do you draw the baseline in pencil?

A

the ink would interfere with the solvent

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10
Q

retention factor (Rf) values

A
  • Rf factor used to compare the components of various samples
  • the unknown Rf values can be compared with the known value
  • if two substances have the same Rf value then it is likely that they are of the same compound
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11
Q

Rf equation

A

distance from the baseline to the spot / distance from the baseline to the solvent front

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12
Q

test for hydrogen

A

a lit wooden splint makes a popping sound in a test tube of hydrogen.

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13
Q

test for oxygen

A

a glowing wooden splint relights in a test tube of oxygen.

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14
Q

test for carbon dioxide

A

carbon dioxide turns limewater cloudy/milky

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15
Q

test(s) for chlorine

A
  • sharp smell
  • bleaches damp blue litmus paper
  • makes damp starch-iodide paper turn blue-black
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16
Q

what is a pure substance?

A

a substance made up of only one time of atom or molecule OR single element or compound that is not mixed with any other substance

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17
Q

what is the physical test for water?

A
  • melting point: 0 degrees
  • boiling point: 100 degrees
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18
Q

how can you test if a substance is pure?

A

you can use their melting and boiling points

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19
Q

what happens if the substance is impure in terms of melting and boiling points?

A
  • when something is impure, it boils over a range, rather than a single degree
  • the MORE impure something is, the LOWER the melting point (+ a larger range)
  • the MORE impure something is, the HIGHER the boiling point
20
Q

what is a formulation?

A
  • useful mixture with a precise purpose (!!!)
  • they are made by following a specific ‘formula’
  • each component in a formulation is present in a measured quantity, and contributes to the properties of the formulation so it meets its required function
21
Q

what makes paint a formulation?

A
  • pigment: gives the paint colour
  • solvent: used to dissolve other components and alter the viscosity
  • binder: forms a film that holds the pigment in place after it has been painted onto a surface
  • additives: added to further change the physical and chemical properties of the paint
22
Q

examples of pure substances:

A
  • distilled water
  • bar or iron
  • acetone
  • hexane
23
Q

examples of formulations:

A
  • face cream
  • paint
  • nail varnish
  • alloys
  • drugs/medicines
  • cleaning agents
24
Q

what is the test for hydrogen?

A

a lit wooden splint makes a popping sound in a test tube of hydrogen

25
Q

what is the test for oxygen?

A

a glowing wooden splint relights in a test tube of oxygen

26
Q

what is the test for carbon dioxide?

A

carbon dioxide turns limewater cloudy/milky

27
Q

what is the test for chlorine?

A

sharp smell, bleaches damp blue litmus paper, makes damp starch-iodide paper turn blue/black

28
Q

what is the test for carbonates? and what is the observations?

A
  • you add a dilute acid to a carbonate
  • it fizzes (effervescence) and produces carbon dioxide gas (lime water becomes cloudy)
29
Q

what is the test for chloride ions?

A
  • add dilute nitric acid and then a silver nitrate solution
  • a white precipitate forms
30
Q

what is the test for bromide?

A
  • add dilute nitric acid and then a silver nitrate solution
  • a cream precipitate forms
31
Q

what is the test for iodide?

A
  • add dilute nitric acid and then a silver nitrate solution
  • a yellow precipitate forms
32
Q

what is the test for sulfates?

A
  • adding a dilute hydrochloric acid followed by a barium chloride solution
  • a white precipitate tells you that sulfate ions are present
33
Q

what is precipitate?

A

a solid formed by a change in a solution

34
Q

what is the test for halides on general?

A

1) add dilute nitric acid
* removes any soluble carbonate or hydroxide impurities… because if those were present, then they’d alter the results
2) add a few drops of silver nitrate and a precipitate will form

35
Q

what is the test for sulfate ions?

A

1) acidify the sample with dilute hydrochloric acid and then add a few drops of aqueous barium chloride
2) if a sulfate is present and then a white precipitate of barium sulfate is formed

36
Q

what is a flame test?

A
  1. wire loop is dipped in concentrated acid and heated
    why do have to heat it?
    * to get rid of contaminants like ions that are already on the loop
    2) dip it into the compound to test and then place it into a bunsen burner flame
37
Q

how do you conduct a flame test?

A
  1. wire loop is dipped in concentrated acid and heated
    why do have to heat it?
    * to get rid of contaminants like ions that are already on the loop
    2) dip it into the compound to test and then place it into a bunsen burner flame
38
Q

what are the observations for the flame tests?

A
  • lithium - crimson
  • sodium - yellow
  • potassium - lilac
  • calcium - orange/red
  • copper - green
39
Q

what is the test for the presence of Ca 2+? and what is the observation?

A
  • add sodium hydroxide
  • forms a white precipitate
  • add more sodium hydroxide
  • no change; white precipitate remains
40
Q

what is the test for the presence of Mg 2+? and what is the observation?

A
  • add sodium hydroxide
  • forms a white precipitate
  • add more sodium hydroxide
  • no change; white precipitate remains
41
Q

what is the test for the presence of Cu2+ and what is the observation?

A
  • add sodium hydroxide
  • forms a blue precipitate
42
Q

what is the test for the presence of Fe2+ and what is the observation?

A
  • add sodium hydroxide
  • forms a green precipitate
43
Q

what is the test for the presence of Fe3+ and what is the observation?

A
  • add sodium hydroxide
  • forms a brown precipitate
44
Q

how do you diffrentiate between the presence of calcium and magnesium?

A
  • by doing a further flame
  • if the flame turn orange-red if calcium present and if not, then magnesium is present
45
Q

what is the test for the presence of Al 3+and what is the observation?

A
  • white precipitate
  • add more
  • white precipitate dissolves

chemistry (6 decks)

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