13. Solutions Flashcards
What are the possible solutions? (solvent and solute)
What are the changes in enthalpy when a solute is dissolved in solvent?
Bonds broken - endothermic (betwen solvent-solvent and solute-solute)
New bonds formed - exothermic (between solvent-solute)
What are the changes in entropy when a solute is dissolved in solvent?
Disorder increases → entropy increases
What are the changes in Gibbs E when solute is dissolved in solution?
How is the activity of a solution defined at a certain T?
What is the relationship between K and Q?
Q is determined for a reaction at a specific point in time, K - at equilibrium, when Q=K - the reaction is at equilibrium
What is the Le Chatelier’s principle?
How to calculate solubility product Ksp?
Involves activities instead of concentrations
Which solution would dissolve the least amount of AgCl? pure water, NaCl, NaBr
NaCl - according to La Chatelier’s principle the equilibrium of AgCl ionisation would be shifted to the left because abundance of Cl- ions in the solution
What is the common ion effect?
When a salt is added to a solution already containing the one of the ions into which the salt dissociates - solubility decreased → precipitate will form
How can formation of precipitate be predicted?
Using reaction quotient Q - not necessarily at equilibrium - will tell if excess of ions or not - precipitate will form or not in comparison to the solubility product (Ksp)
How supersaturation is created? Why is it possible?
salt dissolved - temperature raised - more dissolved - slowly cooled down → supersaturated solution (very precise conditions must be created) - solute molecules are kinetically trapped
How to calculate Kw?
