CH1: EXPERIMENTAL CHEM Flashcards
1
Q
What is the SI unit for time?
A
Second (s)
2
Q
What is the SI unit for temperature?
A
Kelvin (K)
3
Q
Kelvin to Celcius conversion
A
Temp in K = Temp in °C + 273
4
Q
SI unit for length?
A
metre (m)
5
Q
SI unit for mass?
A
Kilograms (kg)
6
Q
SI unit for volume?
A
Cubic meter (m3)
7
Q
Which apparatuses are used to measure length?
A
- measuring tape
- meter ruler
8
Q
Which apparatuses are used to measure time?
A
analogue and digital stopwatches
9
Q
Is an analogue or digital stopwatch more accurate?
A
Digital.
Digital stopwatch measures to 0.01s
Analogue stopwatch measures to 0.1s
10
Q
Which apparatuses are used to measure temperature?
A
- thermometer
- data logger
11
Q
Which apparatuses are used to measure mass?
A
- beam balance
- electronic balance
12
Q
Which apparatuses are used to measure volume of liquids?
A
- pipette
- volumetric flask
- measuring cylinder
- burette
13
Q
When should a pipette be used?
A
To measure accurate FIXED volumes up to 25cm3
14
Q
When should a volumetric flask be used?
A
To measure accurate FIXED volumes of LARGER quantities to 2 d.p.
15
Q
When should a measuring cylinder be used?
A
To measure A RANGE of volumes to the nearest 0.5cm3
16
Q
When should a burette be used?
A
To measure A RANGE of volumes to the nearest 0.05cm3.
17
Q
Which apparatus is used to measure the volume of gas?
A
A gas syringe
18
Q
List the methods for collecting gases
A
- Water displacement
- Downward delivery
- Upward delivery
19
Q
The method used to collect a gas depends on which of its physical properties?
A
- Solubility in water
- Density
20
Q
Explain the properties of a gas that is suitable for water displacement.
A
- insoluble to slightly soluble
- can be denser or less dense than air (density does not affect gas collection)
21
Q
Explain the properties of a gas that is suitable for downward delivery.
A
- can be soluble or insoluble
- denser than air
22
Q
Explain the properties of a gas that is suitable for upward delivery.
A
- can be soluble and insoluble
- less dense than air
23
Q
Examples of gases that can be collected through downward delivery.
A
- chlorine
- hydrogen chloride
- sulfur dioxide
24
Q
Examples of gases that can be collected through water displacement.
A
- oxygen
- hydrogen
- carbon dioxide
25
Examples of gasses that can be collected through upward delivery.
ammonia
26
List the methods for drying gases
1. Concentrated sulfuric acid
2. Calcium oxide/Quicklime
3. Fused calcium chloride
27
Both calcium chloride and calcium oxide must be _____ before use.
Both calcium chloride and calcium oxide must be HEATED before use.
28
Concentrated sulfuric acid is not suitable for gases which ___.
... react with sulfuric acid.
(such as ammonia)
29
What does fused calcium chloride do?
Calcium chloride ABSORBS MOISTURE from the air.
30
What does calcium oxide do?
Calcium oxide ABSORBS MOISTURE and CARBON DIOXIDE from the air
31
Calcium oxide/quicklime is not suitable for gases which____.
... react with calcium oxide.
(such as carbon dioxide and hydrogen chloride)
32
Examples of gases that can be dried using concentrated sulfuric acid.
most gases, including chlorine and hydrogen chloride
33
Why can’t ammonia be dried using concentrated sulfuric acid?
It is an alkali so it will react with sulfuric acid and neutralise to form salt and water
34
Examples of gases that can be dried through calcium oxide/quicklime
ammonia
35
Examples of gases that can be dried through fused calcium chloride
- hydrogen
- nitrogen
- carbon dioxide
36
List the different type of mixtures.
1. solid-solid mixture
2. solid-liquid mixture
3. liquid-liquid mixture
37
What separation techniques are used to separate solid-solid mixtures?
1. magnetic attraction
2. sieving
3. using suitable solvents (dissolving)
4. sublimation
38
Describe the method of magnetic attraction.
Using a magnet to separate magnetic solids from non-magnetic solids.
39
Describe the method of sieving.
Using a sieve to separate solids with different particle sizes.
40
Solute and Solvent definition.
Solute: substances that dissolve in the solvent
Solvent: liquids that dissolve substances
41
Define solubility
The ability of a solute to dissolve in a solvent.
42
When can suitable solvents be used to separate solid-solid mixtures?
When the solids in the mixture have DIFFERENT SOLUBILITIES in DIFFERENT SOLVENTS and only ONE solute is soluble in the solvent.
43
When can sublimation be used to separate solid-solid mixtures?
Sublimation can be used to separate a mixture of solids that change from **solid to gaseous state** directly **after heating** while the other is stable at the sublimation temperature.
44
What apparatuses are used for sublimation.
1. evaporating dish
2. inverted filter funnel
45
The resulting solid deposit of sublimation is known as____.
Sublimate
46
List the separation techniques for solid-liquid mixtures.
- Filtration
- Evaporation to dryness
- Crystallisation
- Simple distillation
47
Describe the method of filtration.
Using a filter to separate insoluble solids from liquids.
The liquid passes through the filter paper and is collected as the filtrate. The insoluble solid remains in the filter paper and is collected as the residue.
48
When is evaporation to dryness used?
Evaporation to dryness is used to separate a DISSOLVED SOLID from a solution by HEATING the solution until all the solvent has VAPORISED.
49
The substance with the (higher/lower) boiling point will turn into gas first.
The substance with the LOWER boiling point will turn into gas first.
50
Why can't sugar be separated using evaporation?
When a sugar solution is strongly heated, the sugar BURNS and BREAKS DOWN into a BLACK SOLID. Therefore, sugar cannot be separated from its solution by evaporation.
51
When is crystallisation used as a separation technique
Crystallisation is used to obtain a PURE SOLID from its SATURATED SOLUTION.
52
Define what a saturated solution is.
A saturated solution is one in which the solute has completely dissolved in.
53
When is simple distillation used as a separation technique?
To separate mixtures with substances of significantly different boiling points
54
What is the pure solvent collected at the end of distillation called?
The distillate
55
Which way does the water enter and exit the condenser? Why?
Bottom in, top out.
1. more efficient to condense the vapour
2. ensures complete condensation of all the vapour passing through the condenser.
56
Function of boiling chips.
To ensure smooth boiling.
57
List the separation techniques used to separate liquid-liquid mixtures.
- separating funnel
- chromatography
- fractional distillation
- simple distillation
58
What are miscible liquids?
Miscible liquids are those which form a uniform HOMOGENEOUS solution when mixed together.
59
What are immiscible liquids?
Immiscible liquids are those which form HETEROGENEOUS mixtures.
60
When a heterogenous mixture of
two or more immiscible liquids are left undisturbed, they can separate into layers known as ________.
Phases
61
Function of a separating funnel
A separating funnel is used to separate immiscible liquids in a heterogeneous solution by letting them settle into their phases.
62
Function of chromatography.
Chromatography is used to separate a mixture of MISCIBLE LIQUIDS which have DIFFERENT SOLUBILITIES in a given solvent.
63
More soluble substances will move more rapidly towards the _______.
More soluble substances will move more rapidly towards the SOLVENT FRONT.
64
Retention factor equation
Rf value = dist travelled by solute ÷ dist travelled by solvent front
65
Conditions needed to compare the solubility of different colours on the chromatograms.
1. dissolved in the same solvent
2. under the same temperature.
66
What precautions need to be taken for paper chromatography?
1. start line drawn in pencil as graphite is not soluble in water -> won't interfere with the separation of the mixture.
2. start line should be above solvent level so solvent won't dissolve the mixture before it can be separated into its components.
3. spot of the mixture should not be too large to prevent the separated contents from overlapping onto one another
4. a lid should be used to cover the container to prevent evaporation of the solvent (esp. if solvent is volatile)
67
How to identify colourless substances on chromatograms?
Using LOCATING AGENTS
such as iodine or examining chromatogram under UV light
to react with colourless substances to form coloured spots
68
Where should the thermometer be placed in the fractioning column?
At the mouth of the condenser.
69
When is fractional distillation used?
- separate miscible liquids
- with similar boiling points
70
Why does the fractioning column contain glass beads?
To provide a larger surface area for the vapours to condense on.
71
How can the purity of a substance be determined?
1. (liquid) Heat the substance up and if it has a fixed boiling point, it is pure.
2. (solid) Heat the substance up and if has a fixed melting point, it is pure.
2. Separate the solution through paper chromatography. If there is only one spot on the chromatogram, it is pure.
72
What is a volitile liquid?
A liquid that evaportates easily.
73
Examples of magnetic and non-magnetic metals.
magnetic: iron, steel, cobalt, nickel
non-magnetic: copper, aluminium, silver, zinc
