Electrochemistry and Colligative properties Flashcards
in electrochemistry, the goal is to get __ ___ out of __ __ or vice versa
electrical work, chemical reaction
Electrical work is one type of _____ work. In a process at constant pressure and temperature, the maximum non-expansion work that can be extracted from a system in a ___ __ is equal to the change in __ __ by this process.
non-expansion, reversible process, gibbs energy
a cell that produces electricity as a result of a spontaneous chemical reaction in the cell
galvanic cell
a cell who’s reaction is driven by an external source of current from humans
electrolytic cell
The ___ is where oxidation takes place, and the ___ is where the reduction takes place. The reaction at the ___ always appears at the left.
anode, cathode, anode
The ___ equation gives a relation between the electromotive force and the __ ___ in the cell. Ecell and Ecell° are both ___, being independent of the ____ chosen for the cell reaction
nernst, actual concentration, intensive, size
The __ ___ electrode potential is set to be 0 at all temperatures, and the reaction is ______. The standard electrode potential of an electrode is the emf measured for a cell where the ___ electrode is the standard hydrogen electrode, and the ___ is the one in question with all components in their standard states.
standard hydrogen, 2H+ + 2e –> H2, left, right
To calculate the emf of a total reaction, it is the ____ - ____, where the right hand side is the more _____ and greater magnitude ___ ___
rhs, lhs, positive, reduction potential
For a spontaneous cell, the ecell is ___, while if the backwards reaction is spontaneous the ecell is ____. Ecell is __ at equilibrium
positive, negative, 0
For a whole cell reaction, to calculate the total ecell, calculate the ecell of each cell separately using its ______ __ ___, and taking into account the number of _____ in each reaction. Then it is ______ -_____. In the standard emf, the amount of ___ is not included in the equation
standard reduction potentials, electrons, rhs, lhs, electrons
In a half reaction, the standard emf and emf need to be calculated from the _______ ____ ____
gibbs free energy
The effect of a solute is to ____ the boiling point of a solvent and to ___ its freezing point.
raise, lower
bB is the ___ of the solute, in other words, the ____ of solute / ____ of solvent
molality, moles, kg
Kb is the _____ constant and it depends on the type of solvent only. It is equal to ____/____
ebullioscopic, MRTb^2/Hvap
Kf is the ____ constant and it depends on the type of solvent only. it is equal to ____/___
MRTf^2/Hfus
Colligative properties like the elevation. of the boiling point and depression of the freezing point depend only on the ____ of solute particles and not on the ___ of solute molecules
number, identity
Xb is the mole fraction of the solute, in other words, the number of moles of the ____ over the number of moles of the ____. Or the number of moles of the solute over (___/___)
solute, solvent, mass(solvent)/Mw(solvent)
The flow of pure solvent through a semipermeable membrane into a more concentrated solution
osmosis
The pressure that must be applied to the concentrated solution to stop the inward flow of solvent
osmotic pressure
In an ___ environment, the amount of ions in and out of the cell are the same. In a ____ environment, there are more solutes in the cell, and water will enter the cell, and it will ___. In a _____ environment, there are less solutes inside the cell and water will flow out of the cell, making it ____
isotonic, hypotonic, lyse, hypertonic, shrivel
For a solvent in a solution, the gibbs free energy is ____ than the standard gibbs free energy for a pure solvent at standard pressure. This is because the activity in the equation for gibbs free energy is equal to the __ ___. If there is any solute present, the mole fraction will be ___ than 1 and the gibbs free energy will be smaller. This is the __ ___ behind why pure solvent travels to the solution side. The equilibrium conditions is that the gibbs free energies of both sides are ____.
less, mole fraction, less, driving force, equal
the osmotic pressure of the solution with respect to the pure solvent is ___. This pressure results because of the ____ gibbs free energy of the solution in comparison to the solvent. The solvent will migrate through the membrane to increase the ___ ____ on the solution until the free energies are equal
p-p°, smaller, hydrostatic pressure
At constant ___ for a ___ solution, the osmotic pressure is proportional to the ___ of the ____
temperature, dilute, molarity/concentration, solute
The distribution between ions between two solutions in contact through a semipermeable membrane at equilibrium, with one solution containing an electrolyte protein ion that cannot permeate the membrane
Donnan membrane equilibrium
The potential difference across the membrane due to a concentration difference of individual ion on each side of the membrane
donnan potential
When there are unequal concentrations of ions across the membrane, there is ____ of the solvent, and thus an ___ ___ difference.
migration, osmotic pressure
The inside and outside membrane ___ ___ must both equal ___.
charge balances, 0
Any cell delivering current to an external circuit is operating ___ since the current flow is generated by a -___ reaction. This means we can’t measure the full electrical potential of the cell because part of it is being used to generate ___ __. To measure the true cell potential, we must operate under conditions of ___ __ _ _, by using a __ ___ to balance the emf against a known standard voltage so that no current flows.
irreversibly, spontaneous, current flow, 0 current flow, potentiometer circuit
By having the spontaneous process occur in an electrochemical cell we can use the decrease in __ __ __ to drive an electron flow through the __ __ and produce net work.
gibbs free energy, external circuit
The ____ cell is one where metallic zinc and a copper electrode are immersed in _____ and ___ solutions respectively
daniell, ZnSO4, CuSO4
With metal to metal electrodes, the reacting species are in _ ___ with each other and the __ ___. You can use these to figure out when one metal will ___ another from solution
intimate contact, external circuit, displace
In a metal to insoluble salt electrode, components must be arranged so they are in ____ amongst themselves and can be in ___ contact with the other half. This is useful in the measurement of ___ ___ ___
contact, electrical, solubility product constants
Gas electrodes where two H electrodes have different concentrations of ___ could be used as a ___ ___. The emf would be equal to about ____pH
H+, pH meter, 0.0592
The 4 colligative properties are ___ __ ___, __ _ ___, __ __ ___, and __ __
vapor pressure lowering, freezing point depression, boiling point elevation, osmotic pressure
Colligative properties assume that the solute is _____ so the only gas present is the solvent vapor, and that the solute is _____ in the solid solvent
non-volatile, insoluble
When a solute is added to a pure solvent, the entropy ___, and thus the gibbs free energy _____. The gibbs free energy of the ___ and ___ meanwhile stays the same. This means that the freezing point ____ and the boiling point ____
increases, decreases, solid, liquid, decreases, increases
When a substance is added to a pure liquid, there is more ____ in the solution, so there is less tendency for the solvent to ___ and acquire the higher entropy of its ____. in other words, when there is already more entropy in the solution, ____ vapor has to form ___ the free energies of the two phases, so ___ __ is lowered and boiling point is raised
randomness, escape, vapor, less, equalize, vapor pressure
Similarly for melting point, the enhanced __ of the solution increases the tendency of the solid to __ and it is able to do so at a ____ temperature than that for a pure solvent.
randomness, melt, lower
Colligative properties are related to ___ and not ___ because they change how the molecules move around, not how they interact with each other on an ____ ____
entropy, enthalpy, intermolecular level
The largest effects for boiling point elevation will be found for solvents with high ___ __ and low _____ _____ _____
boiling points, enthalpies of vaporization
Large freezing point depressions are favoured by solvents with high __ __ and low ___ _ ___
melting points, enthalpies of fusion
water has a cryoscopic constant of ____, benzene _____, phenol ___, and camphor ____
1.86, 5.12, 7.27, 40
For a given solvent the __ _____ ____ is more accurate in general than __ __ ____ for determining either __ ___ of unknown solutes or the number of particles formed by ___ __ in solution
freezing point depression, boiling point elevation, molecular weights, ionic solutes
For ____ such as proteins in solution, because osmotic pressure depends only on the number of ____ molecules, the effects are much ___
macromolecules, solute, smaller
During the donnan membrane equilibrium condition, all parts of both solutions must remain ___ ___ at all times so that the ions must diffuse across the membrane together and in ____ ____. Only those species to which the membrane is ____ are able to reach equilibrium across the membrane and only those are included in the donnan conditions
electrically neutral, equal amounts, permeable
To measure the donnan potential accurately, we need to add electrodes that are _____ into each solution
ion-selective
