Etiket Arşivleri: Bülent BELİBAĞLI
Example: What is the osmotic pressure at 25⁰C of an aqueous solution that is 0.001 M sucrose ?
Example: A solution of an unknown substance in water at 298 K gives rise to an osmotic pressure of 5.66 atm. What is the molarity of the solution ?
Example: A solution prepared by dissolving 20 mg of insulin in water and diluting to a volume of 5.0 mL gives an osmotic pressure of 12.5 mmHg at 300 K. What is the molecular weight of insulin ?
3. Effect of Temperature on Equilibrium
The equilibrium constant is temperature dependent.
• For an endothermic reaction, DH > 0 and heat can be considered as a reactant.
• For an exothermic reaction, DH < 0 and heat can be considered as a product.
a. Raising the temperature of an equilibrium mixture shifts the equilibrium condition in the direction of the endothermic reaction.
b. Lowering the temperature of an equilibrium mixture shifts the equilibrium condition in the direction of the exothermic reaction.
The stronger the H-A bond, the weaker the acid should be.
The strong bonds are characterized by short bond lengths and high bond dissociation energies.
Example: 50 mL of 0.0155 M HI(aq) is mixed with 75 mL of 0.0106 M KOH(aq). What is the pH of the final solution ?
Spontaneous Change: Entropy and Free Energy
Spontaneity: A spontaneous process is a process that occurs in a system left to itself; once started, no action from outside the system (no external actions) is necessary to make the process continue. i.e., the process proceeds on its own without any external influence.
A non-spontaneous process will not occur without external action continuously applied.
Standard free energy of a substance = f(T, P, state of substance, concentration,…). The Standard free energy change (ΔG⁰) corresponds to reactant’s and product’s free energies in their Standard states.
(ΔG⁰) = G⁰products – G⁰reactants
The Standard free energy of formation (ΔGf⁰) is the free energy change for a reaction in which a substance in its Standard state is formed from its elements in their most stable forms in their Standard states. Free energies of formation of the elements in their most stable forms at 1 atm pressure is zero.