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CHEMISTRY > 3.1 INTRODUCTION + SEPARATING TECHNIQUES > Flashcards

3.1 INTRODUCTION + SEPARATING TECHNIQUES Flashcards

1
Q

3 signs of a PHYSICAL change

A
  • Creates no new substances
  • Are usually easy to reverse
  • Absorb or release small ammounts of energy
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2
Q

3 signs of a CHEMICAL change

A
  • Creates new substances
  • Usually difficult to reverse
  • Absorb or release large amounts of energy
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3
Q

Chemical test for water

A

Anhydrous Copper(II) Sulfate turns from white to blue

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4
Q

Physical test for water

A

Pure water will boil at 100c

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5
Q

Define an element

A

A substance containing one type of atom only

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6
Q

Typical properties of metals

A
  • High MP/BP
  • Electrical conductors
  • Malleable
  • Shiny
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7
Q

Typical properties of non-metals

A
  • Low MP/BP
  • Electrical insulators
  • Brittle
  • Dull
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8
Q

Diatomic Molecules

A

Nitrogen, Oxygen, Hydrogen + Halogens

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9
Q

Define a compound

A

A substance containing more than one type of atom, chemically bonded together

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10
Q

Define a mixture

A

A substance containing more than one type of atom not chemically bonded together

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11
Q

How does the ammonium chloride tube illustrate diffusion

A
  • Ammonium chloride forms as a white smoke towards the hydrogen chloride end
  • The hydrogen chloride molecules are heavier so diffuse slower compared to ammonia
  • Heating the tube will speed up the reaction but not change the results
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12
Q

Define solute

A

The substance which is going to be dissolved

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13
Q

Define solvent

A

The liquid which is going to do the dissolving

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14
Q

Define solution

A

The resulting mixture of a solute dissolved in a solvent

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15
Q

Define saturated

A

A solution in which no more solute can be dissolved

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16
Q

Define suspension

A

A solid floating in a liquid because it cannot dissolve

17
Q

Define soluble

A

A substance which can be dissolved

18
Q

Define insoluble

A

A substance which cannot be dissolved

19
Q

How is solubility measured

A
  • g / 100g solvent
  • You can use it as a ratio and scale it up and down
20
Q

How do solubility curves work

A
  • Measures solubility compared to temperature
  • Below the line = soluble
  • On the line = saturated
  • Above line = insoluble
21
Q

How do you carry out a chormatography experiment

A
  • Draw a line near the bottom of the paper in pencil - as it won’t dissolve in the solvent
  • Add spots of different dyes at regular intervals
  • Place paper in beaker of solvent - with solvent below pencil line, so inks don’t dissolve into solvent
  • Place lid on beaker - to stop solvent evaporating
  • Allow solvent to move up paper until it is just below the top
  • Take paper out and mark solvent front
  • Allow paper to dry
22
Q

How do you carry out paper chromatography

A
  • Draw a base line in pencil at the bottom of the chromatography paper - so it doesn’t dissolve in solvent
  • Add spots of dye on line in different inks
  • Place paper in beaker of solvent - ensure below solvent line so it doesn’t dissolve into solvent
  • Place lid on beaker - to prevent solvent evaporating
  • Allow solvent to move up paper, until it is near the top
  • Take the paper out and mark solvent front
  • Allow paper to dry
23
Q

What happens to soluble dyes in chromatography

A

They will move further up the paper

24
Q

What happens to soluble dyes in chromatography

A

They will move further up the paper

25
Q

What happens if a dye is insoluble in chromatography

A

It will not move from the baseline

26
Q

In terms of physical properties, what is the differance between a pure substance and a mixture

A

A Pure substance has a fixed boiling point, but a mixture may melt/boil over a range of temperatures

27
Q

What is filtration used for

A

To seperate a solid from a liquid

28
Q

Describe how to carry out filtration

A
  • Place filter paper in funner and pour in solution
  • Residue is substance left in filter paper
  • Filtrate is liquid that comes through filter paper
29
Q

What is crystalisation used for

A

To seperate a solute from a solution

30
Q

Describe how to carry out crystalisation

A
  • Solution is heated in evaporating basin to boil off water, until an almost saturated solution is formed
  • Bunsen is turned off and crystals allowed to form as more water evaporates and solution forms
  • Crystals removed by filtration
31
Q

Describe how to carry out crystalisation

A
  • Solution is heated in evaporating basin to boil off water, until an almost saturated solution is formed
  • Bunsen is turned off and crystals allowed to form as more water evaporates and solution forms
  • Crystals removed by filtration
32
Q

What is simple distillation used for

A

To seperate pure water from a solution

33
Q

Describe how to carry out simple distillation

A
  • Water from solution boils and is condensed back into liquid by condenser
34
Q

What is fractional distillation used for

A

Seperate ethanol from a mixture of ethanol and water

35
Q

How to carry out fractional distillation

A
  • Control heating temperature to ensure water condenses in column and trickles back into flask
  • Only ethanol with lower boiling point (than water) remains as vapour at top of fractionating column, and into condensor
36
Q

Where to measure ink from a chromatgram

A

Centre of the spot

37
Q

How to calculate Rf

A

Distance oved by spot (from pencil line) / Distance moved by solvent (from pencil line)

38
Q

Purpose of chromatography

A

To seperate inks from dyes

CHEMISTRY (17 decks)

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