Topic 2 Flashcards
2.1
Describe the properties of a solid
(Hint: arrangement, movement, relative energy, volume, closeness, compressed?)
-Arranged in a regular, fixed pattern
-Vibrate around fixed point
-Low energy
-Fixed volume
-Very close together
-Can’t be compressed
2.1
Describe the properties of a liquid
(Hint: arrangement, movement, relative energy, volume, closeness, compressed?)
-Randomly arranged
-Can move freely
-Greater energy than solids
-Fixed volume
-Close together
-Can’t be compressed
2.1
Describe the properties of a gas
(Hint: arrangement, movement, relative energy, volume, closeness, compressed?)
-Randomly arranged
-Can move freely
-Lot of energy
-Don’t have fixed volume
-Lots of space between particles
-Can be compressed
2.2
Name the interconversion from solid to liquid
Melting
2.2
Name the interconversion from liquid to gas
Evaporation
2.2
Name the interconversion from gas to liquid
Condensation
2.2
Name the interconversion from liquid to solid
Freezing
2.2
Name the interconversion from solid to gas
Sublimation
2.2
Name the interconversion from gas to solid
Deposition/Reverse sublimation
2.2
What type of changes are interconversions between states of matter
Physical changes
2.2
What is a physical change?
-Reversible
-Change in state
-Change in arrangement
-Chemical properties don’t change
-No new material
2.2
What is a chemical change?
-Irreversible
-Chemical properties change
-New material formed
2.2
What 4 things can be seen while a chemical change is taking place?
-Colour change
-Heat/light given off (Temperature change)
-Precipitate
-Effervescence
2.2
Which change (physical or chemical) is irreversible? Why?
-Chemical
-Chemical compounds formed
-You’d have to pull apart molecules and rebuild in original form - difficult
2.2
Is dissolving tablets in water a physical or chemical change? Is it reversible or irreversible?
-Physical
-Reversible
2.2
Is a bunsen burner burning gas a physical or chemical change? Is it reversible or irreversible?
-Chemical
-Irreversible
2.2
Is a magnesium dropped in an acid a physical or chemical change? Is it reversible or irreversible?
-Chemical
-Irreversible
2.3
Explain the conversion from a solid into a liquid
-When heated -> particles gain KE -> vibrate more around fixed point
-Intermolecular bonds separate
-F of attraction holding particles together overcome -> particles spread apart
-Move faster (more KE)
2.3
Explain the conversion from a liquid to a solid
-When cooled -> particles move less bc decreased KE
-Intermolecular bonds form
2.4
State the melting and boiling point for water
Mp - 0°
Bp - 100°
Define the term fixed (arrangement)
Can’t move around
Define the term regular (arrangement)
Clear pattern
2.4
Ethanol has a mp of -114°C and a bp of 78°C. Predict what state of matter it will be at the following temperatures:
-250
-100
0
25
250
You may draw a number line to help
-250 = Solid
-100 = Liquid
0 = Liquid
25 = Liquid
250 = Gas
Define the term compound
2 or more different types of elements chemically joined together
Define the term element
Substance made up of only 1 type of atom
Define the term molecule
2 or more atoms chemically joined together
Define the term mixture
-2 or more diff. elements NOT chemically joined together
-Easily separated
2.5
What is a pure substance?
Contains only 1 element or compound
2.5
True or false: Air is pure
Why?
-False
-Contains carbon dioxide, oxygen, nitrogen…
-Compounds not chemically joined with each other
-So it is a mixture
2.6
Why does the temperature of the heating curve of a pure substance stay constant when it is changing state?
All KE being used to overcome IM (intermolecular) bonds
2.6
Sketch a diagram to show what a heating curve for a pure substance would look like
Replace heat added with energy added. Add bp and mp on straight lines. Ignore the 4 labels.
https://www.google.com/search?q=heating+curve+gcse&tbm=isch&ved=2ahUKEwif3fXcueX-AhW5rycCHegTCLoQ2-cCegQIABAA&oq=heating+curve+gcse&gs_lcp=CgNpbWcQAzIFCAAQgAQ6BwgAEIoFEENQvg9Y6hpggRxoAHAAeACAAYQCiAHfB5IBBTAuMi4zmAEAoAEBqgELZ3dzLXdpei1pbWfAAQE&sclient=img&ei=jMZYZJ_nHrnfnsEP6Keg0As&bih=629&biw=1300&rlz=1CAOBDQ_enGB939&safe=active&ssui=on#imgrc=iMm0b6QssSsooM&imgdii=xZHQGRPT60TsHM
2.6
Compare the heating curve of pure and impure substances
-Pure substances change state at single temperature (sharp melting point)
-Whereas impure substances change state over range of temperatures
2.7
What do simple and fractional distillation separate?
Mixture of solutions
2.7
Explain how simple distillation works
-Heat solution to temp. of liquid with lowest bp (Bunsen burner)
-Liquid evaporates up tube -> condenser condenses vapour to liquid
-Collected in beaker
-Other liquid still in flask
2.7
What are the risks when carrying out simple distillation? How can you prevent them?
-Shattering glass (suck back), take delivery tube out whilst still heating & wear goggles
-Burning rubber = carcinogens (cancer causing fumes), keep rubber away from heat
-Burning lanyard/hair, take off & tie up
2.7
You want to separate three liquids. Explain how you can use fractional distillation to do this
-Heat solution to temp of liquid with lowest bp (Bunsen burner)
-Liquid evaporates up fractionating column
-Condenser cools vapour -> liquid collected in beaker
-Other liquid may evaporate -> cold glass rods condense back into liquid (bc are cooler than the bp) iquid falls back into flask
-Raise temp -> repeat for next liquid
2.7
What does filtration separate?
Insoluble substance from liquid
2.7
Explain how filtration works
-Pour mixture into filter paper
-Liquid passes through
-Solid can’t
2.7
What does crystallisation separate?
Soluble substance from liquid
2.7
Explain how crystallisation works
-Heat solution in evaporating basin -> evaporates water
-Crystals left behind
2.7
Why should you be careful when heating a solution in crystallisation?
-Heating could affect chemical trying to crystalise
-Some chemicals break down when heated
2.7
What is the stationary phase in paper chromatography? Why?
-The paper
-Because it does not move
2.7
What is the mobile phase in paper chromatography? Why?
-The solvent
-Because it moves
2.9
What does chromatography separate?
Mixture of soluble substances e.g dye, ink
2.9
Explain how to carry out chromatography
-Pencil line at bottom of filter paper
-Space out dots of each sample on line
-Bottom of paper into solvent (solvent reach just below pencil line)
-Travels up paper -> dissolves inks
-Inks also travel up paper at different rates
2.10a
In chromatography, how can you tell whether a substance is pure or impure?
Pure = Single dots in all solvents
Impure = Multiple dots
2.10c
State the formula used to calculate the Rf value.
How can you check your answer?
-Rf= Distance travelled by dye/Distance travelled by solvent
-Ans always between 0-1
2.10c
What does a larger Rf value mean?
More soluble
Define the term solvent
Able to dissolve other substances
Define the term solute
Can be dissolved in a solvent
Define the term solution
Mixture formed when solute is dissolved in solvent
Define the term soluble
Can be dissolved
Define the term insoluble
Can not be dissolved
2.12a
Define the term potable
Drinkable
2.12a
What are the stages involved in treating water in order to make it potable?
-Sedimentation
-Filtration
-Chlorination
2.12a
Describe what happens in sedimentation when treating water
Sediments sink to bottom of reservoir
2.12a
Describe what happens in filtration when treating water
-Dirty water travels through sand & water
-Sediments get stuck
-Water goes through
2.12a
Describe what happens in chlorination when treating water
Chlorine added to water to kill bacteria & micro-organisms
2.12b
Describe how sea water can be made potable using simple distillation
-Water evaporates to form water vapour
-Salt left in beaker
-Water vapour condenses to form pure water
2.12c
Why must distilled water be used for chemical analysis?
-Is pure
-Tap water contains dissolved salts -> interfere w/ results
-Incorrect results will be obtained
