CHEMISTRY LEVEL 3
- 1.1 Boyle's Law
- 1.2 Charles'law
- 1.3 Combined gas law
- 1.4 Standard conditions
- 1.5 Diffusion and Graham's law
- 2.1 Relative Mass
- 2.2 Atoms, Molecules and Moles
- 2.3 Compounds and the mole
- 2.4 Empirical and Molecular formula
- 2.5 Concentration of a solution
- 2.6 Molar solutions
- 2.7 Preparation of molar solutions
- 2.8 Dilution of a solution
- 2.9 Stoichiometry of chemical reactions
- 2.10 Volumetric analysis
- 2.11 Titration
- 2.12 Redox titration
- 2.13 Atomicity and molar gas volume
- 2.14 Combining volumes of gases
- 3.1 Alkanes
- 3.1.1 Formulae of alkanes
- 3.1.2 Cracking of alkanes
- 3.1.3 Nomenclature (systematic naming) of alkanes
- 3.1.4 Isomerism in alkanes
- 3.1.5 Laboratory preparation of alkanes
- 3.1.6 Physical properties of alkanes
- 3.1.7 Chemical properties of alkanes
- 3.1.8 Uses of alkanes
- 3.2 Alkenes
- 3.2.1 Nomenclature of alkenes
- 3.2.2 Isomerism in alkenes
- 3.2.3 Laboratory preparation of ethene
- 3.2.4 Physical properties of alkenes
- 3.2.5 Chemical properties of alkenes
- 3.2.6 Test for alkenes
- 3.2.7 Uses of alkenes
- 3.3 Alkynes
- 3.3.1 Nomenclature of alkynes
- 3.3.2 Isomerism in alkynes
- 3.3.3 Laboratory preparation of ethyne
- 3.3.4 Physical properties of alkynes
- 3.3.5 Chemical properties of alkynes
- 3.3.6 Test for alkynes
- 3.3.7 Uses of alkynes
- 3.4 Recommended practice of topic summary
- 4.1 Extraction of nitrogen from air
- 4.2.1 Laboratory preparation of nitrogen gas from the air
- 4.2.2 Laboratory preparation of nitrogen gas from ammonium nitrite (NH4NO2)
- 4.2.3 Uses of nitrogen
- 4.3 Oxides of nitrogen
- 4.3.1 Nitrogen (I) oxide
- 4.3.2 Nitrogen (II) oxide
- 4.3.3 Nitrogen (IV) oxide
- 4.4.1 Laboratory preparation of ammonia
- 4.4.2 Solubility of ammonia in water
- 4.4.3 Reactions of aqueous ammonia (ammonia solution)
- 4.4.4 Reactions of ammonia gas
- 4.4.5 Industrial manufacture of ammonia: The Haber Process
- 4.4.6 Uses of ammonia
- 4.4.7 Nitrogenous fertilizers
- 4.5.1 Laboratory preparation of nitric (V) acid
- 4.5.2 Industrial manufacture of nitric (V) acid
- 4.5.3 Reactions of dilute nitric (V) acid
- 4.5.4 Reactions of concentrated nitric (V) acid
- 4.5.5 Uses of nitric (V) acid
- 4.6.1 Action of heat on nitrates
- 4.6.2 Test for nitrates (nitrate ions, NO3-)
- 4.6.3 Air pollution by nitrogen compounds
- 4.7 Summary on nitrogen and its compounds
- 5.0 Sulphur and its Compounds
- 5.1.1 Extraction of sulphur
- 5.1.2 Allotropes of sulphur
- 5.1.3 Physical properties of sulphur
- 5.1.4 Chemical properties of sulphur
- 5.2.1 Preparation of sulphur (IV) oxide
- 5.2.2 Physical properties of sulphur (IV) oxide
- 5.2.3 Chemical properties of sulphur (IV) oxide
- 5.2.4 Reducing action of sulphur (IV) oxide
- 5.2.5 Oxidization of SO2 to SO3
- 5.2.6 Oxidizing action of sulphur (IV) oxide
- 5.2.7 Test for sulphite (SO32-) and sulphate (SO42-) ions
- 5.2.8 Uses of sulphur (IV) oxide
- 5.3 Large scale (industrial) manufacture of sulphuric (VI) acid
- 5.3.1 Physical properties of concentrated sulphuric (VI) acid
- 5.3.2 Chemical properties of concentrated sulphuric (VI) acid
- 5.3.3 Reactions of dilute sulphuric (VI) acid
- 5.4 Hydrogen sulphide
- 5.4.1 Chemical properties of hydrogen sulphide
- 5.4.2 Air pollution by compounds of sulphur
- 5.5 Summary on sulphur and its compounds
- 6.1 Occurrence of chlorine
- 6.2 Laboratory preparation of chlorine
- 6.3 Physical properties of chlorine
- 6.4 Chemical properties of chlorine
- 6.5 Oxidizing properties of chlorine
- 6.6 Reaction of chlorine with alkaline solutions
- 6.7 Test for chloride ions
- 6.8 Uses of chlorine and its compounds
- 6.9 Preparation of hydrogen chloride gas
- 6.10 Physical properties of hydrogen chloride
- 6.11 Chemical properties of hydrogen chloride
- 6.12 Industrial manufacture of hydrochloric acid
- 6.13 Uses of hydrochloric acid
Gas Laws: Charles's Law
1.0 Gas Laws
1.2 Charles's Law
(How V varies with T at constant P)
Figure 1.2(a): Charles's law domonstration
Questions 1.2(a): (Based on previous experience) 
- What happens to a rubber balloon when inflated in a cool morning then left hanging out for long hours till the Sun becomes hot?
- During heating in the Sun, you may not see the volume changing. What is the evidence that volume of the trapped air changes?
- What happens to temperature of the trapped gas (or air)?
- Which of the quantities P, V and T is more or less constant in this case?
- How does the volume of a gas vary with temperature?
Answers to Questions 1.2(a) 
From everyday life experience with rubber balloons, volume of a fixed mass of gas increases with temperature. But what, precisely, is the equation relating volume and temperature?
Figure 1.2(b): Set-up to investigate Charles's law
Observe the video demonstration on Charles's law experiment.
Questions 1.2(b)
The data in Table 1.2 were obtained in an experiment to determine how the volume of a fixed amount of dry air varies with temperature.
Table 1.2 : Data from Charles's law experiment
- Suggest two reasons why concentrated sulphuric (VI) acid is used as the index to indicate height or volume of air column.
- Plot a graph of l (vertical axis) against the absolute temperature in kelvin, K. l represents volume, V, of trapped air (Air is used to represent a gas).
- From the graph, state the law that relates volume of a fixed mass of gas to absolute temperature (Charles's law).
- Write a mathematical equation to represent the relationship.
- The vessel containing air was a glass tube with uniform cross-sectional area. Explain why the information highlighted in bold is important.
Answers to Questions 1.2(b)
NB: This is a clear case where we vary temperature to see how it affects volume and not the other way round. We have not changed temperature by varying volume. Therefore, temperature is plotted on the horizontal axis. We also consider this when stating the law. We say, "Volume of a fied mass of gas is proportional to ... constant", and not "Temperature of a fixed mass of gas is proportional to ... constant".
Charles's Law: Volume of a fixed mass of gas is directly proportional to its absolute temperature, provided its pressure remains constant.
V α T; T/V = Constant, k.
V1/T1 = V2/T2
Figure 1.2(c): Illustration
Observe (or think of) the changes that occur on the absolute temperature (T), and volume (V) of the balloon as the flame is moved closer to the balloon.
Questions 1.2(c)
A gas occupies 500 ml at room temperature (25 oC) and pressure. At what temperature will its volume be double if pressure remains constant?
Answers to Questions 1.2(c)