Topic 1: Quantitative chemistry (12.5 hours)
1.1The mole concept and Avogadro’s constant
2 hours
TOK: Assigning numbers to the masses of the chemical elements allowed chemistry to develop into a physical science and use mathematics to express relationships between reactants and products.
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Assessment statement |
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1.1.1 |
Apply the mole concept to substances. |
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The mole concept applies to all kinds of particles: atoms, molecules, ions, electrons, formula units, and so on. The amount of substance is measured in moles (mol). The approximate value of Avogadro’s constant (L), 6.02 × 1023 mol–1, should be known. TOK: Chemistry deals with enormous differences in scale. The magnitude of Avogadro’s constant is beyond the scale of our everyday experience. |
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1.1.2 |
Determine the number of particles and the amount of substance (in moles). |
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Convert between the amount of substance (in moles) and the number of atoms, molecules, ions, electrons and formula units. |
1.2Formulas
3 hours
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Assessment statement |
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Teacher’s notes |
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1.2.1 |
Define the terms relative atomic mass (Ar) and relative molecular mass (Mr). |
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1.2.2 |
Calculate the mass of one mole of a species from its formula. |
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The term molar mass (in g mol–1) will be used. |
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1.2.3 |
Solve problems involving the relationship between the amount of substance in moles, mass and molar mass. |
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1.2.4 |
Distinguish between the terms empirical formula and molecular formula. |
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1.2.5 |
Determine the empirical formula from the percentage composition or from other experimental data. |
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Aim 7: Virtual experiments can be used to demonstrate this. |
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1.2.6 |
Determine the molecular formula when given both the empirical formula and experimental data. |
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1.3Chemical equations
1 hour
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Assessment statement |
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1.3.1 |
Deduce chemical equations when all reactants and products are given. |
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Students should be aware of the difference between coefficients and subscripts. |
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1.3.2 |
Identify the mole ratio of any two species in a chemical equation. |
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1.3.3 |
Apply the state symbols (s), (l), (g) and (aq). |
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TOK: When are these symbols necessary in aiding understanding and when are they redundant? |
1.4Mass and gaseous volume relationships in chemical reactions
4.5 hours
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Assessment statement |
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1.4.1 |
Calculate theoretical yields from chemical equations. |
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Given a chemical equation and the mass or amount (in moles) of one species, calculate the mass or amount of another species. |
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1.4.2 |
Determine the limiting reactant and the reactant in excess when quantities of reacting substances are given. |
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Aim 7: Virtual experiments can be used here. |
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1.4.3 |
Solve problems involving theoretical, experimental and percentage yield. |
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1.4.4 |
Apply Avogadro’s law to calculate reacting volumes of gases. |
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1.4.5 |
Apply the concept of molar volume at standard temperature and pressure in calculations. |
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The molar volume of an ideal gas under standard conditions is 2.24 × 10−2 m3 mol−1 (22.4 dm3 mol−1). |
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1.4.6 |
Solve problems involving the relationship between temperature, pressure and volume for a fixed mass of an ideal gas. |
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Aim 7: Simulations can be used to demonstrate this. |
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1.4.7 |
Solve problems using the ideal gas equation, PV = nRT |
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TOK: The distinction between the Celsius and Kelvin scales as an example of an artificial and natural scale could be discussed. |
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1.4.8 |
Analyse graphs relating to the ideal gas equation. |
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1.5Solutions
2 hours
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Assessment statement |
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1.5.1 |
Distinguish between the terms solute, solvent, solution and concentration (g dm–3 and mol dm–3). |
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Concentration in mol dm–3 is often represented by square brackets around the substance under consideration, for example, [HCl]. |
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1.5.2 |
Solve problems involving concentration, amount of solute and volume of solution. |
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