Experimental Chemistry Flashcards
1
Q
What is the International System of Units (SI Units)?
A
A common standard for measurements
It is used to ensure consistency in scientific measurements.
2
Q
What is the SI unit for mass?
A
kilogram (kg)
Other units include gram (g) and tonne (t).
3
Q
What is the SI unit for time?
A
second (s)
Other units include minute (min) and hour (h).
4
Q
What is the SI unit for temperature?
A
kelvin (K)
Other unit includes degree Celsius (°C).
5
Q
What is the SI unit for volume?
A
cubic metre (m³)
Other units include cubic centimetre (cm³) and cubic decimetre (dm³).
6
Q
Convert 1 kg to grams.
A
1000 g
This is a standard conversion in the SI unit system.
7
Q
Convert 1 tonne to kilograms.
A
1000 kg
Tonne is a larger unit of mass equivalent to 1000 kilograms.
8
Q
What is the accuracy of an electronic balance?
A
$0.01 g
This indicates the precision of the measurement.
9
Q
Convert 1 minute to seconds.
A
60 s
A minute consists of 60 seconds.
10
Q
Convert 1 hour to minutes.
A
60 min
An hour consists of 60 minutes.
11
Q
What is the formula to convert temperature from Celsius to Kelvin?
A
T (K) = T (°C) + 273
This formula is essential for converting between these temperature scales.
12
Q
What apparatus can be used to measure liquid volumes accurately?
A
- measuring cylinder
- burette
- pipette
Each apparatus has a different level of precision.
13
Q
What is the measuring capacity of a gas syringe?
A
up to 100 cm³
This tool is specifically designed for gas measurements.
14
Q
What is the accuracy of a digital stopwatch?
A
$0.01 s
Digital stopwatches provide precise time measurements.
15
Q
What instruments can be used to measure temperature?
A
- analogue thermometer
- digital thermometer
- temperature sensor/probe
These instruments vary in technology and accuracy.
16
Q
Fill in the blank: 1 m³ = _______ dm³.
A
1000 dm³
This conversion is important for understanding volume in different units.
17
Q
What is the measurement accuracy of an analogue stopwatch?
A
$0.1 s
This indicates that it can measure time with a precision of one-tenth of a second.
18
Q
What unit is used to measure fixed volumes in liquids?
A
pipette
Pipettes are designed to deliver specific volumes, such as 10.0 cm³ or 25.0 cm³.
19
Q
What is the curve called that forms when a liquid is placed in a container?
A
Meniscus
Most liquids have a concave meniscus, while mercury has a convex meniscus.
20
Q
What type of meniscus do most liquids, such as water, have?
A
Concave meniscus
Concave meniscus curves upwards at the edges.
21
Q
What type of meniscus does mercury have?
A
Convex meniscus
Convex meniscus curves downwards at the edges.
22
Q
What should be aligned to the meniscus when reading the volume of a liquid?
A
The eye
This alignment prevents parallax error.
23
Q
What apparatus should be used to measure the time taken for calcium carbonate powder to dissolve in hydrochloric acid?
A
Digital stopwatch
The apparatus must measure time accurately.
24
Q
What apparatus should be used to measure 10.0 cm of sulfuric acid?
A
Pipette
The apparatus must measure fixed volumes of liquids.
25
What apparatus should be used to measure 16.85 cm of aqueous potassium hydroxide?
Burette
## Footnote
The apparatus must measure liquid volumes to the nearest 0.05 cm.
26
What apparatus should be used to measure 65.0 cm of oxygen gas?
Gas syringe
## Footnote
The apparatus must measure the volume of a gas.
27
What apparatus should be used to measure 2.35 g of salt?
Electronic balance
## Footnote
The apparatus must measure mass to the nearest 0.01 g.
28
What factors influence the method of collecting a gas?
Solubility in water and density compared to air
## Footnote
These properties determine how a gas is collected.
29
What is the method of collecting gas that uses a delivery tube and gas jar?
Delivery tube and gas jar
30
What is the method of collecting gas that involves displacement of water?
Displacement of water
31
Which gas is insoluble in water?
Hydrogen
32
Name a gas that is slightly soluble in water.
Oxygen or carbon dioxide
33
What is the method used for downward delivery of gas?
Downward delivery of gas
34
Which gas is soluble in water?
Chlorine
35
What gas is very soluble in water?
Hydrogen chloride or sulfur dioxide
36
What type of gas is denser than air?
Denser than air
37
Which gas is less dense than air?
Ammonia
38
How can the volume of a gas be measured using water?
Inverted measuring cylinder filled with water
39
What apparatus can be used to measure the volume of a gas?
Gas syringe
40
What is a common drying agent for gases?
Concentrated sulfuric acid
41
What type of gas can be dried using concentrated sulfuric acid?
Most gases, excluding ammonia
42
What drying agent is used for ammonia?
Quicklime (calcium oxide)
43
Which gases can be dried using fused calcium chloride?
Hydrogen, nitrogen, carbon dioxide
44
Fill in the blank: Concentrated sulfuric acid can dry most gases except for those that react with it, such as _______.
Ammonia
45
Fill in the blank: Quicklime can dry _______ but cannot be used for gases that react with it, like hydrogen chloride.
Ammonia
46
Fill in the blank: Fused calcium chloride can dry hydrogen, nitrogen, and carbon dioxide, but not _______.
Ammonia
47
What is the apparatus used for in the example?
To dry and collect gas Q
## Footnote
Gas Q is identified as hydrogen chloride.
48
What is the relationship between gas Q and the densities of ammonia and hydrogen chloride?
Ammonia is less dense than air; hydrogen chloride is denser than air
## Footnote
This affects the method of gas collection.
49
What is the identity of gas Q?
Hydrogen chloride
## Footnote
It is an acidic gas.
50
What is substance P in the apparatus?
Fused calcium chloride
## Footnote
It is used to dry hydrogen chloride.
51
What is substance O in the apparatus?
Quicklime
## Footnote
Quicklime reacts with hydrogen chloride.
52
What is a mixture?
A mixture is made up of two or more substances that are not chemically combined.
53
What defines a pure substance?
A pure substance is made up of only one element or compound.
54
What characterizes a substance with impurities?
It has a different chemical composition from the pure substance.
55
What determines the method to remove impurities from a substance?
The properties of each substance in the mixture.
56
List three methods to separate mixtures.
* Filtration
* Evaporation
* Crystallization
57
True or False: A mixture can consist of substances that are chemically combined.
False
58
Fill in the blank: A substance with impurities has a different _______ from the pure substance.
chemical composition
59
What are locating agents used for in chromatography?
To locate colourless compounds.
60
What is the primary goal of separating mixtures?
To purify the components.
61
What method can be used to separate an insoluble solid from a liquid?
Filtration
## Footnote
The insoluble solid is collected as the residue and the liquid as the filtrate.
62
What is the term for the liquid collected after filtration?
Filtrate
## Footnote
The filtrate is the liquid that passes through the filter paper.
63
What is the residue in the context of filtration?
Insoluble solid
## Footnote
The residue is the solid that remains on the filter paper.
64
What process can be used to obtain a soluble solid from a solution by heating?
Evaporation to dryness
## Footnote
This method is effective for solids that do not decompose on heating.
65
What happens to the solvent during the evaporation process?
Changes into a gas
## Footnote
The solvent, having a lower boiling point than the solute, evaporates first.
66
What is an example of a soluble solid that can be obtained through evaporation?
Salt
## Footnote
Salt is a common example as it does not decompose when heated.
67
What is crystallisation used for?
To obtain a soluble solid from a solution
## Footnote
This method is suitable for solids that decompose on heating, like sugar.
68
What is a saturated solution?
A solution in which no more solute can be dissolved in the solvent
## Footnote
This is the state required for crystallisation to occur.
69
What is 'water of crystallisation'?
Water that is fixed in the crystal lattice
## Footnote
This water is essential for forming crystals; if evaporated, the solid will be a powder.
70
List the steps involved in the process of crystallisation.
* Heat the solution until saturated
* Leave the hot saturated solution to cool
* Filter to collect the crystals
* Wash the crystals with cold distilled water
* Dry the crystals between filter paper
## Footnote
These steps ensure proper formation and collection of crystals.
71
True or False: Evaporation to dryness is suitable for obtaining solids that decompose on heating.
False
## Footnote
Evaporation to dryness is suitable for solids that do not decompose on heating.
72
What method can be used to separate an insoluble solid from a liquid?
Filtration
## Footnote
The insoluble solid is collected as the residue and the liquid as the filtrate.
73
What is the term for the liquid collected after filtration?
Filtrate
## Footnote
The filtrate is the liquid that passes through the filter paper.
74
What is the residue in the context of filtration?
Insoluble solid
## Footnote
The residue is the solid that remains on the filter paper.
75
What process can be used to obtain a soluble solid from a solution by heating?
Evaporation to dryness
## Footnote
This method is effective for solids that do not decompose on heating.
76
What happens to the solvent during the evaporation process?
Changes into a gas
## Footnote
The solvent, having a lower boiling point than the solute, evaporates first.
77
What is an example of a soluble solid that can be obtained through evaporation?
Salt
## Footnote
Salt is a common example as it does not decompose when heated.
78
What is crystallisation used for?
To obtain a soluble solid from a solution
## Footnote
This method is suitable for solids that decompose on heating, like sugar.
79
What is a saturated solution?
A solution in which no more solute can be dissolved in the solvent
## Footnote
This is the state required for crystallisation to occur.
80
What is 'water of crystallisation'?
Water that is fixed in the crystal lattice
## Footnote
This water is essential for forming crystals; if evaporated, the solid will be a powder.
81
List the steps involved in the process of crystallisation.
* Heat the solution until saturated
* Leave the hot saturated solution to cool
* Filter to collect the crystals
* Wash the crystals with cold distilled water
* Dry the crystals between filter paper
## Footnote
These steps ensure proper formation and collection of crystals.
82
True or False: Evaporation to dryness is suitable for obtaining solids that decompose on heating.
False
## Footnote
Evaporation to dryness is suitable for solids that do not decompose on heating.
83
What is simple distillation used for?
To separate a solvent from a solute.
84
Which solvent can be separated from salt using simple distillation?
Water.
85
In simple distillation, which component changes into vapour first?
The solvent with a lower boiling point.
86
What remains in the distillation flask after the solvent has evaporated?
The solute.
87
What happens to the vapour in the condenser during distillation?
It cools and condenses back into a liquid.
88
What is collected in the conical flask during distillation?
The distillate.
89
What is left in the distillation flask after all the solvent has vaporized?
The residue.
90
How can a magnetic solid be separated from a non-magnetic solid?
Using a magnet.
91
Which metals are known to be magnetic?
* Iron
* Cobalt
* Nickel
92
What is an example of a magnetic compound?
Magnetite.
93
What is sublimation in the context of separation techniques?
The process where a substance changes from solid to gaseous state directly.
94
Which substance is mentioned as undergoing sublimation?
Ammonium chloride.
95
Fill in the blank: A _______ can be used to separate a magnetic solid from a non-magnetic solid.
magnet
96
Fill in the blank: The liquid collected in the conical flask during distillation is called the _______.
distillate
97
How can a soluble solid be separated from an insoluble solid?
By dissolving the soluble solid in a suitable solvent and carrying out filtration
## Footnote
The insoluble solid is collected as the residue, and the soluble solid can be obtained from the filtrate by evaporation to dryness or crystallization.
98
What is the residue in the separation of a soluble solid from an insoluble solid?
The insoluble solid collected after filtration
## Footnote
The soluble solid is obtained from the filtrate.
99
What are immiscible liquids?
Liquids that do not dissolve in each other
## Footnote
Examples include petrol and water.
100
What is the first step in using a separating funnel?
Pour the mixture of two immiscible liquids into the separating funnel and wait for two layers to form
## Footnote
The less dense liquid will form a layer above the denser liquid.
101
What do you do after the two layers form in a separating funnel?
Open the tap and allow the bottom layer to flow into a beaker, then close the tap
## Footnote
This allows for the separation of the denser liquid.
102
What is the purpose of fractional distillation?
To separate miscible liquids with different boiling points
## Footnote
It utilizes differences in boiling points for separation.
103
Fill in the blank: The apparatus used in fractional distillation includes a _______.
fractionating column
## Footnote
Other components include a thermometer, Liebig condenser, and round-bottomed flask.
104
What is the role of the thermometer in fractional distillation?
To monitor the temperature of the boiling liquid
## Footnote
It helps in determining the boiling point of the liquid being distilled.
105
What happens to the less dense liquid when using a separating funnel?
It forms a layer above the denser liquid
## Footnote
This allows for easier separation.
106
What is obtained as the distillate in fractional distillation?
Ethanol
## Footnote
The distillate is collected in a receiving flask.
107
What happens when a mixture containing two miscible liquids is heated?
Both liquids change into vapours
## Footnote
This process is part of fractional distillation.
108
What occurs to the vapour of the liquid with the higher boiling point during fractional distillation?
It condenses into a liquid in the fractionating column and flows back into the round-bottomed flask
## Footnote
This helps to purify the liquid with the lower boiling point.
109
What happens to the vapour of the liquid with the lower boiling point in fractional distillation?
It reaches the top of the fractionating column and enters the condenser, where it condenses into a liquid
## Footnote
This liquid is collected as the distillate.
110
In fractional distillation, what is collected first in the conical flask?
The liquid with the lower boiling point
## Footnote
This is known as the distillate.
111
What happens to the temperature in the fractionating column after the lower boiling point liquid has distilled over?
The temperature increases to reach the boiling point of the remaining liquid
## Footnote
This indicates that the higher boiling point liquid is now being distilled.
112
What does the thermometer measure during fractional distillation?
The temperature of the vapour that enters the condenser
## Footnote
It does not measure the temperature of the liquid in the round-bottomed flask.
113
True or False: Fractional distillation can be used to separate immiscible liquids.
False
## Footnote
Fractional distillation is only applicable to miscible liquids.
114
What is a common misconception regarding simple distillation and fractional distillation?
Simple distillation can separate a mixture of miscible liquids
## Footnote
This is incorrect; only fractional distillation can effectively do so.
115
What is required for distillation to effectively separate miscible liquids?
A significant difference in the boiling points of the liquids, i.e., more than 50 °C
## Footnote
This allows for effective separation during the distillation process.
116
What is chromatography used for?
To separate a mixture of substances with different solubilities in a given solvent
## Footnote
It involves distributing substances between stationary and moving phases.
117
In paper chromatography, how does the solvent interact with the stationary phase?
The solvent moves up the stationary chromatography paper, carrying the substances to be separated
## Footnote
This movement aids in the separation process.
118
What happens to more soluble substances in chromatography?
They move more quickly with the solvent than the less soluble substances
## Footnote
This results in the separation of substances in the mixture.
119
What is the chromatography paper with separated substances called?
A chromatogram
## Footnote
This visual representation shows the results of the separation process.
120
What is the retention factor (R value) in chromatography?
The ratio between the distance travelled by a substance and the distance travelled by the solvent
## Footnote
It is a constant value for each substance under the same conditions.
121
Fill in the blank: The R value is calculated using the formula: R value = _______.
distance travelled by the substance / distance travelled by the solvent
122
True or False: The R value of a substance changes under different conditions.
True
## Footnote
The R value is dependent on the specific conditions of the chromatography process.
123
What is a characteristic of colourless substances in chromatography?
They may require visualization techniques to be seen on the chromatogram
## Footnote
This is important for interpreting results.
124
What happens to the distances travelled by substances and the solvent over time in chromatography?
The distances increase with the time given for the chromatogram to develop.
125
What is the R value in chromatography?
R value = distance travelled by substance / distance travelled by solvent front
126
What remains constant for the R value of a substance?
The R value does not change as long as the chromatogram is obtained under the same conditions.
127
What factors must remain the same for the R value to be consistent?
* Same solvent
* Same temperature
128
How can colourless substances be visualized on a chromatogram?
By spraying the chromatogram with a suitable locating agent.
129
What is the minimum number of substances in a mixture if multiple spots are present on a chromatogram?
At least one substance must be present for each distinct spot.
130
In a chromatogram, how can you identify compounds present in a mixture?
Draw a line from the centre of the spot for each substance parallel to the start line and solvent front.
131
Fill in the blank: The distance moved by a spot is taken from the _______ to the start line.
centre of the spot
132
True or False: The R value can change if the temperature of the chromatogram changes.
True
133
What visual aid can help identify substances in a chromatogram?
A diagram that shows the position of the spots for the mixture and pure compounds.
134
What is the first step to purify a sample of sugar contaminated with sand?
Dissolve the sample of sugar in the minimum amount of water.
135
What is the characteristic of sugar in relation to water?
Sugar is soluble in water while sand is insoluble.
136
What should be done after filtering the mixture of sugar and sand?
Collect the filtrate.
137
What is the next step after collecting the filtrate?
Heat the filtrate until a hot saturated solution is obtained.
138
What should be done after obtaining a hot saturated solution?
Allow the hot saturated solution to cool slowly for sugar crystals to form.
139
What is the purpose of washing sugar crystals with distilled water?
To purify the sugar crystals.
140
Why is measuring the purity of substances important?
It helps to identify harmful impurities and ensures quality standards.
141
How can the purity of a substance be determined using chromatography?
A pure substance will only give a single spot in the chromatogram.
142
What indicates the presence of impurities in a chromatogram?
Multiple spots with different Rf values.
143
What are the characteristics of a pure substance's melting and boiling points?
They are constant and fixed.
144
How do impurities affect the melting point of a substance?
Impurities lower the melting point.
145
How do impurities affect the boiling point of a substance?
Impurities raise the boiling point.
146
Fill in the blank: A pure substance has _______ melting and boiling points.
[constant and fixed]
147
True or False: The more impurities present, the higher the melting point of the substance.
False
148
Which method can be used to deduce the identities of substances based on their physical properties?
Measuring melting and boiling points.
149
What is the result of filtering the mixture of dissolved sugar and sand?
The sand is removed, and the sugar remains in the solution.
150
What happens to sugar crystals after cooling the hot saturated solution?
Sugar crystals form.
