Reactivity 2. How much, how fast and how far?
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2.1 Amount of chemical change
• Show ratio of reactants and products • Deduce balanced equations, including state symbols, from named reactants and products
• Determine masses, volumes, concentrations • Use balanced equations for reacting quantity calculations
• Determines theoretical yield • Identify limiting and excess reactants from given data
• (Experimental yield / Theoretical yield) × 100% • Solve problems involving theoretical, experimental, and percentage yields
• Measure of green chemistry efficiency • Calculate atom economy and link low atom economy to waste
2.2 Rate of chemical change
• Change in concentration per unit time • Determine rates from tangents of concentration, volume, or mass graphs
• Sufficient energy + proper orientation required • Kinetic energy and temperature (Kelvin) • Explain successful collisions using activation energy and orientation
• Pressure, concentration, surface area, temperature, catalyst • Predict and explain rate changes when conditions change
• Minimum energy for successful collision • Maxwell-Boltzmann distribution curves • Use Maxwell-Boltzmann curves to show temperature effects on successful collisions
• Provide alternative pathway with lower Ea • Energy profiles with/without catalysts • Explain catalyst effects on energy profiles and Maxwell-Boltzmann distributions
2.3 Extent of chemical change
2.3.1Dynamic equilibrium
• Forward rate = backward rate (closed system) • Describe physical and chemical systems at equilibrium
2.3.2Equilibrium law
• K determined from stoichiometry • Deduce K expressions for homogeneous reactions
2.3.3Equilibrium constant (K)
• Magnitude indicates extent of reaction • Temperature dependent • Kreverse = 1/Kforward • Interpret K << 1, K < 1, K = 1, K > 1, and K >> 1
2.3.4Le Châtelier's principle
• Predict effects of changes in concentration, temperature, pressure • Include effects on K and equilibrium composition