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LEARNING OUTCOME
1.1 Experimental design
(a) name appropriate apparatus for the measurement of time, temperature, mass and
volume, including burettes, pipettes, measuring cylinders and gas syringes
(b) suggest suitable apparatus, given relevant information, for a variety of simple
experiments, including drying and collection of gases and measurement of rates of
reaction
EXPERIMENTAL
CHEMISTRY
Topic 1
HOW ARE PHYSICAL QUANTITIES MEASURED?
Physical
Quantity
Time
SI Unit
Symbol
Other common Units
Temperature
Length
Mass
second
s
Minute (min), hour (h)
kelvin
metre
kilogram
K
m
kg
Degree Celcius (oC)
Centimetre (cm), decimetre (dm)
Gram (g), tonne (t)
Volume
Cubic metre
m3
Cubic centimetre (cm3)
Cubic decimetre (dm3)
MEASUREMENT OF TIME
1 min = 60 s
1 h = 60 min
Analogue stopwatch
+0.1 s
Digital stopwatch
+0.01 s
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Unknown
Author is
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MEASUREMENT OF TEMPERATURE
Analogue thermometer
K = oC + 273
Digital thermometer
MEASUREMENT OF LENGTH
1 m = 10 dm = 100 cm = 1000 mm
Accuracy of +0.1 cm
Metre rule
Measuring Tape
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This Photo by Unknown Author is licensed under CC BY-SA
MEASUREMENT OF MASS
MEASUREMENT OF VOLUME
1g = 1000 mg
1 kg = 1000 g
1 t = 1000 kg
Choice of beaker, measuring cylinder, volumetric flask, burette and pipette.
Accuracy of electronic balance is +0.01 g
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licensed under CC BY-SA
7/12/2024
MEASUREMENT OF VOLUME
Apparatus
Beaker
Accuracy
Least Accurate
Measuring Cylinder
Burette
Volumetric flask
Range of volumes +0.5 cm
Range of volumes +0.05 cm
Accurate fixed volumes
Pipette
Accurate fixed volumes
Meniscus
– avoid parallax error
MEASURING THE VOLUME OF A GAS
Plunger
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under CC BY-SA
This Photo by Unknown Author is licensed under CC BY-SA
This Photo by Unknown Author is licensed under CC BY-SA-NC
LET’S PRACTICE 1.1
1. What is an advantage of using a burette instead of a measuring cylinder
to measure a volume of liquid?
2. Although a pipette measures volume very accurately, state one
disadvantage of using a pipette to measure liquid volumes.
1.2 HOW ARE
GASES COLLECTED?
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METHODS FOR
DRYING GASES
LET’S PRACTISE 1.2
1. Gas X is less dense than air and is insoluble in water. Suggest a method that can
be used to collect gas X. Draw the set-up.
2. Gas Y reacts with acids. Name one drying agent that can be used on gas Y.
LEARNING OUTCOME
1.3 HOW ARE SUBSTANCES IN MIXTURES
SEPARATED?
1.2 Methods of purification and analysis
(a) describe methods of separation and purification for the components of mixtures,
to include:
 (i) use of a suitable solvent, filtration and crystallisation or evaporation
 (ii) sublimation
 (iii) distillation and fractional distillation
 (iv) use of a separating funnel
 (v) paper chromatography
(b) suggest suitable separation and purification methods, given information about the
substances involved in the following types of mixtures: (i) solid-solid (ii) solid-liquid (iii)
liquid-liquid (miscible and immiscible)
(c) interpret paper chromatograms including comparison with ‘known’ samples and the
use of Rf values
1. Separating solid-solid mixtures
2. Separating solid-liquid mixtures
3. Separating liquid-liquid mixtures
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SEPARATING SOLID-SOLID MIXTURES
SEPARATING SOLID-SOLID MIXTURES
1. Using magnetic attraction
3. Using suitable solvents
Magnets can be used to separate magnetic solids from non-magnetic solids.
A suitable solvent can be used to separate solid-solid
mixtures in which only one of the solids is soluble in the
solvent.
Examples of magnetic materials are:
Iron, cobalt, nickel, steel
2. Sieving
A sieve can be used to separate solids of different particle sizes
Example: mixture of sand and salt
4. Sublimation
When a mixture consists of particles of different sizes, they can be separated by
using a sieve with a suitable pore size.
Sublimation can be used to separate a mixture of solids
where one sublimes on heating while the other does not.
Example: sand and pebbles
Example: mixture of iodine and salt
SEPARATING SOLID-LIQUID
MIXTURES
SEPARATING SOLID-LIQUID MIXTURES
Filtration
Evaporation to Dryness
 Used to separate insoluble solids from
liquid
• Used to separate a dissolved solid from its solvent
by heating the mixture until all the solvent has
vaporized.
 A filter funnel and filter paper are used
 The liquid that passes through is filtrate
 The solid that remains on filter paper is
residue
 Example: sand in water
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• All the solvent (of lower boiling point) are boiled off,
leaving only the solid (higher boiling point) in the
evaporating dish.
• Example:
• Cannot be used for solids that break down or
decompose when heated.
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SEPARATING SOLID-LIQUID MIXTURES
CRYSTALLISATION
Crystallisation
• Used to obtain a pure solid from its saturated solution.
• A saturated solution is one in which no more solute can be dissolved.
• Steps:
• Heat the solution in an evaporating dish until the solution is saturated.
• Cool the solution until solid crystals appear within the solution.
• Filter the mixture to obtain the crystals.
• Wash the crystals with some cold distilled water to remove impurities.
• Dry the crystals with filter paper
Example: sugar solution
SEPARATING SOLID-LIQUID MIXTURES
Simple Distillation is used to separate a pure solvent from a solution.
Example: sea water
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SEPARATING LIQUID-LIQUID MIXTURES
SEPARATING LIQUID-LIQUID MIXTURES
Separating Funnel
Chromatography
• Miscible liquids – form uniform or homogeneous solution
Used to separate a mixture of substances which have different solubilities in a given
solvent.
• Immiscible liquids – form a heterogenous mixture. When
left to settle, they form separate layers (phases). The less
dense layer on top, the denser layer at the bottom.
Chromatogram – show the separated substances on the paper after chromatography
• The more soluble substance will move faster towards the solvent front
• The less soluble substance will move slower towards the solvent front.
• To separate immiscible liquid, use a separating funnel.
The retention factor (Rf) is used for comparison:
• Open the tap at the bottom to drain out the lower layer.
• Pour out the top layer into a beaker.
Rf = distance travelled by the substance / distance travelled by the solvent
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Chromatography
Note: if the solvent is changed, the Rf will be different.
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EXERCISE
SEPARATING LIQUID-LIQUID MIXTURES
A sample of ink from a forged
signature was compared with inks
from the pens of five suspects.
Chromatography of colourless substances
a. Which of the inks, A, B, C, D, or E,
could have been used to write the
forged signature?
Locating agents – react with the colourless substances to form coloured spots
b. Which of the inks must contain a
mixture of at least 3 dyes?
How to view if it is colourless?
UV light – to view the substances visible under UV light
Or use both – use locating agent to react with the colourless substance, then
view under UV light
SEPARATING LIQUID-LIQUID MIXTURES
SEPARATING LIQUID-LIQUID MIXTURES
Applications of Chromatography
Fractional Distillation
Industrial Applications
• used to separate miscible
• Oil refineries separate
liquids with different boiling different substances from
point
crude oil
• Miscible liquids cannot be
• Separation of liquefied air
separated using simple
to produce nitrogen, oxygen
distillation.
and argon gas
• Ethanol produced by
glucose fermentation is
extracted in breweries
• Identify pesticides or poisons in food
• Detect banned substance in athlete’s urine or blood
sample
• Forensic investigation – separate components like
DNA fragments in biological samples
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SEPARATING LIQUID-LIQUID MIXTURES
Fractional Distillation
• A fractionating column is added to the simple
distillation set-up.
• The column contains glass beads to provide large
surface area for vapours to condense.
• At boiling point T1, collect first distillate.
• At boiling point T2, collect second distillate
• Liquids with boiling points close together require longer
fractionating column to separate.
EXERCISE
The apparatus on the right is used to
separate a mixture of two compounds
called octane and decane.
a. What feature must the two liquids
have in order for them to be separated
by this method?
b. What is the piece of apparatus
labelled X called? What does X do?
c. Which liquid appears in the beaker
first? Explain your answer.
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LET’S PRACTICE 1.3
1. Name 2 separation techniques that involve a change of state of one of the
components.
2. Name 2 separation techniques that does not involve a change of state.
1.4 HOW CAN THE PURITY OF SUBSTANCES BE
DETERMINED?
A pure substance has
• a specific melting and boiling point under fixed conditions
• only one spot in the chromatogram
Mixtures melt or boil over a range of temperatures
3. How can components separated in paper chromatograms be identified
against known substances?
EXERCISE
Presence of impurities increases the boiling point of water to more than 100oC,
but decrease the freezing point of water to below 0oC.
Question: Why is salt being added to the road during winter?
EXERCISE