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HL Chapter 7. Equilibrium. Equilibrium. What is liquid- vapour equilibrium? This is a state of equilibrium between a liquid and its vapour in conditions of equilibrium. Equilibrium. What is vapour pressure?
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HL Chapter 7 Equilibrium
Equilibrium • What is liquid-vapour equilibrium? • This is a state of equilibrium between a liquid and its vapour in conditions of equilibrium.
Equilibrium • What is vapour pressure? • It is the measurement of pressure exerted by a vapour on its liquid when equilibrium is reached. • High vapour pressure means large amounts of vapour or low pressure means a less volatile liquid.
Equilibrium • What does vapour pressure depend on? • Temperature: with more energy, more molecules have enough escape kinetic energy. • The nature (volatility) of the substance.
Equilibrium • How does the vapour pressure relate to the increase in temperature? • Rise in vapour pressure is exponential with a rise in temperature.
Equilibrium • How do we determine the volatility of a liquid? • The intermolecular forces determine how stable or volatile a liquid is. • The lower the enthalpy of vaporization, the more volatile a liquid. • ∆Hvaporization is the energy to convert one mole of liquid into gas.
Equilibrium • What is the equilibrium law? • We can use this equation and algebra to find any different part.
Equilibrium • What is the equilibrium constant for a reaction with the following concentrations. • CO .150 mol/dm • H2O .0145 mol/dm • H2 .200 mol/dm • CO2 .0200 mol/dm
Equilibrium • What are the steps to work with the equilibrium law? • 1. write the balanced equation • 2. keep track of initial, change and equilibrium values of concentrations • 3. write the expression for Kc from the balanced equation
Equilibrium • How else can we use the equation? • Calculate constant from initial and equilibrium concentrations. • Calculate concentrations from constant and some concentrations. • Manipulate the constant for different reaction equations.
Equilibrium • SO3 + NO NO2 + SO2 • Kc = 6.78 • Initial concentrations are .0300 mol/dm of SO3 and NO. • What is the equilibrium concentration of each?
Equilibrium • 2H2O 2H2 + O2 • Kc = 7.3 x 10-18 • Initial concentration .10 mol/dm • What is the concentration of hydrogen and oxygen?
Equilibrium • What are some basic manipulations we can make with a change in a reaction equation? • Reversing reaction changes Kc to 1/Kc • Doubling reactants changes Kc to Kc2 • Halving reactants changes Kc to √Kc • Adding 2 reactions multiplies Kc’s