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: Boyle's Law
1.0 Gas Laws
1.1 Boyle's Law
A gas can be described in terms of its Pressure (P), Volume (V), and absolute Temperature (T).
1.1 Boyle's law (How V varies with P at constantT)
Figure 1.1(a): Set-up to demonstrate Boyle's law (ANIM)
Questions 1.1(a): Previous and current experiences
- What happens to the volume, V, and pressure, P, of trapped air when the piston is moved inwards?
- Does this agree with what we observe when an inflated rubber balloon is squeezed?
- What happens to the volume, V, and pressure, P, of trapped air when the piston is moved outwards?
- Does the mass of trapped air change?
- Does the temperature of trapped air change, if the piston is moved slowly?
- How does the volume of a fixed mass of gas at constant temperature vary with pressure?
Answers to Questions 1.1a
NB: Air is used to represent a gas because it is itself a mixture of gases and, physically, it behaves like a gas.
Pressure of a fixed mass of gas increases as volume decreases. But, precisely, how does it? Is the relationship linear (a straight line), or inverse (a curve)? Let us take measurements to answer this question.
Figure 1.1(b): Boyle's law apparatus (ANIM)
h represents excess pressure on the gas in mm of mercury (mmHg)
l represents volume of the gas.
Observe the animated (or video) demonstration of Boyle's law, and record at least six pairs of corresponding values of h and l.
- What happens to the height, h, of mercury column and length, l, of air column as the open limb of the U-tube is raised?
- Plot a graph of l (vertical axis) against h.
- We have used l to represent volume, V. How can we obtain the actual value of V?
- Is the graph linear or inverse?
- State the relationship between volume (V) and pressure (P) of a fixed mass of gas at constant temperature (Boyle's law).
- Write a mathematical equation relating P and V to represent Boyle's law.
Answers to Questions 1.1b
Boyle's law: Pressure of a fixed mass of gas is inversely proportional to volume of the gas if temperature is kept constant.
Figure 1.1(c): Breathing motion demonstrating Boyle's law (ANIM)
In Figure 1.1(c), the outer circle represents a rigid container and the inner circle, the volume of gas contained. As P increases, V decreases and vice versa.
For calculations, P is inversely proportional to V; or PV = Constant, k That is, P1V1 = P2V2 (where 1 and 2 represent initial and final values respectively). NB: In the experiment, pressure P was changed (varied) directly by raising or lowering the free limb of the tube. As a result, V also changed. So, a change in P caused a change in V, in the same manner a change in x causes a change in y in the Cartesian plane. So, P is normally plotted on the horizontal axis. Questions 1.1(c) A fixed amount of gas occupies 450 ml at a pressure of 760 mmHg. Determine its volume at a pressure of 1140 mmHg (1.5 atm) if its temperature
does not change. Answers to Questions 1.1c
P is inversely proportional to V; or PV = Constant, k
P1V1 = P2V2 (where 1 and 2 represent initial and final values respectively).
NB: In the experiment, pressure P was changed (varied) directly by raising or lowering the free limb of the tube. As a result, V also changed. So, a change in P caused a change in V, in the same manner a change in x causes a change in y in the Cartesian plane. So, P is normally plotted on the horizontal axis.
A fixed amount of gas occupies 450 ml at a pressure of 760 mmHg. Determine its volume at a pressure of 1140 mmHg (1.5 atm) if its temperature does not change.
Answers to Questions 1.1c