Colligative Properties GChem

krabi's version from 2015-07-15 23:15


Question Answer
What is a strong electrolyte vs. weak electrolyte?Strong ionic substances fall apart completely; weak substances remain ion paired. Strong electrolytes better conduct electricity.
What is a non-Electrolyte?Covalent compounds that do not dissociate into ions.
What is the Van Hoff factor?The ionizability factor (i) tells us how many ions one unit of a substance will produce in a solution.
What is the Van Hoff factor for biomolecules?i = 1; non-ionic hormones, proteins, etc.
What is i = 2?When NaCl dissociates into Na & Cl.
What is i = 3?CaCl2 dissciates into Ca and 2 Cl-.
What are the solubility rules for salt in water? In ORDER1) All Group I (Li, Na, K, Rb, Cs) and ammonium (NH4) salts are soluble. 2) All nitrate, percholate and acetate salts are soluble. 3) All silver, lead, and mercury are insoluble (except for their nitrates, perchlorates, and acetates).
What is the symbol for nitrate, percholate and acetate salts?NO3- & ClO4- & C2H3O2 -
What are colligative properties?: a) Solubility of solids in liquids (increase w/++temp) b) Solubility of gases in liquids (decrease w/++ temp) c) Solubility of gases in liquids (increase w/++ pressure).
Question Answer
What are the phase solubility rules?They are trends. Depends on the number of solute particles in the solution, (rather than the type of particle). NB the van hoff particle to ID particles.
What are 4 kinds of colligative properties?Vapour pressure depression, boiling point elevation, freezing point depression and osmotic pressure. Relationship between solute and solvent. Applies the capillaries.
Vapour pressure depression? Air near lake is more humid than in-land. Dynamic equilibrium between gas & liquid molecules. Weak IMFs, ++ vapour pressure, and the more easily it evaporates. Volatile water, liquids w/high vapour pressure.
How do solutes impact VP?A dissolved solute, the solute molecules attach to solvent molecules and act as anchors. Thus, ++ Energy req’d to enter gas phase (since solvent molecules have to break away from IMFs between).
What is the boiling point of a liquid?Defined as the temperature at which VP of the solution = atm pressure. Adding more solute to the solution will decrease the VP. eg. adding salt to too make boiling water boil sooner.
What is an application of Daltons Law?Solution of 2 liquids VP of AB = A + B (VP)
What is Raoult’s Law Ideal Solution Law?To calculate partial pressures: the partial VP of A or B is proportional to its mole fraction in the solution. p = X P
How do solutions deviate from Raoult’s Law?If IMF attractions in a mixed punch, molecules will escape from liquid solution into gas phase more easily than if it was pure 100% fruit juice. Partial VPs will be higher than predicted by Raoult’s Law.
What is boiling point elevation?When a liquid boils, the molecules in liquid needs to overcome IMF and break free into gas phase.
What happens when a non-volatile solute is added to the liquid?Solute particles are attached to solvent molecules and act as anchors.
What is the boiling point elevation trend?For a given solvent, the more solute particles there is ⇒ the greater the BP elevation: In order for molecules they need more energy than they did without the solute.
T = kim
Question Answer
What is the freezing point depression?Adding salt to ice: add solute to a liquid and then freeze? Solute will interfere with the ice crystal lattice structure. Thus, harder for ice to stay solid and freezing point decreases and makes less ice. T = - kim
What is the constant k for water?k - 1.9 C/m
What is Osmosis?The net movement of water across a semipermeable membrane from low concentration of solutes to high concentration. The water moves, not the solute across the semipermeable membrane. The net movement of the water will always go to the right.
What is osmotic pressure?The pressure it would take to STOP osmosis. Osmotic pressure = MiRT
What impacts osmotic pressure?Impacted by number of particles in the solution w/Van Hoff. Is NOT impacted by the identity of those particles.