Gen Chem 2 – Flashcards
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| Larger Ksp |
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| more salt in saturated solution |
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| How to increase the solubility if the anion is the conjugate base of a weak acid? |
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| adding strong acid |
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| Qc |
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| [products]/[reactants] |
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| Qsp |
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| Qc[PbF2] = [Pb2+][F-]2 |
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| spontaneous change |
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| occurs without continuous input of energy |
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| activation energy |
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| spontaneous process needs no further input of energy |
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| non-spontaneous change |
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| occurs only if surrounds continuously supply energy |
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| First Law of Thermodynamics |
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| energy is conserved |
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| More order ---> Less order (entropy) |
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| solid ---> liquid ---> gas |
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| More order ---> Less order (entropy) |
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| crystal + liquid ---> ions in solution |
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| S = k ln W |
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| Where S is entropy, W is the number of ways of arranging the components of a system, and k is a constant |
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| smaller W |
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| system with few ways to arrange it's components has less disorder and low entropy |
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| larger W |
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| system with many ways to arrange it's components has more disorder and high entropy |
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| Second Law of Thermodynamics |
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| entropy always increases |
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| reversible process |
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| one that occurs in such tiny increments that the system remains essentially at equilibrium, and the direction of the change can be reversed by an infinitesimal reversal of conditions |
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| Change in 2 for reversible process |
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| Change in S = q/T |
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| Temperature changes with S |
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| as temperature rises, S increase |
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| Physical states with S |
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| More order to less order - S increase |
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| Dissolving a solid or liquid with S |
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| As a solid and liquid dissolve, S increases |
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| Dissolving a gas with S |
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| as a gas dissolved, S increases |
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| Atomic size with S |
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| As mass increases, S increases |
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| Molecular complexity with S |
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| as complexity increases, S increases |
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| G for a spontaneous process |
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| G is the maximum work obtainable from the system as the process takes place. G = work |
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| G for a non-spontaneous process |
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| G is the minimum work that must be done to the system as the process takes place. |
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| more negative G |
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| larger K |
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| small change in G |
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| large change in K |
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| more positive G |
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| smaller K |
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| When an oxidizing agent is reduced |
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| It gains electrons |
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| When a reducing agent is oxidized |
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| It loses electrons |
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| Oxidation |
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| loss of electrons, increase in oxidation number |
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| Reduction |
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| gain of electrons, decrease in oxidation number |
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| Half-Reaction steps in acidic solution |
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| 1. write two half reactions from skeleton reaction 2. balance atoms and charges a. atoms other than O and H b. O atoms - add H2O c. H atoms - add H+ d. charge - add e- where needed 3. Multiple to have the same e- in both reactions 4. Add balanced half reactions 5. Check that atoms are balanced and cancel out |
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| Half-Reaction steps in basic solution |
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| 1. write two half reactions from skeleton reaction 2. balance atoms and charges a. atoms other than O and H b. O atoms - add H2O c. H atoms - add H+ d. charge - add e- where needed 3. Multiple to have the same e- in both reactions 4. Add balanced half reactions 5. Add one OH to both sides of equation for each H present 6. Combine H and OH to form H2O and simplify 7. Check that atoms and charges are balanced |
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| oxidation half-cell |
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| components of anode compartment (left) |
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| reduction half-cell |
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| components of cathode compartment (right) |
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| 1 amp |
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| 1 coulomb/second |
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| 1 volt |
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| 1 joule/coulomb |
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| all standard electrode potentials are |
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| reductions |
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| Ecell equation |
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| Ecell = Ecathode - Eanode |
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| strongest reducing agent |
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| most negative E value on chart |
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| strongest oxidizing agent |
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| most positive E value on chart |
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| Positive E cell values |
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| spontaneous |
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| Negative E cell values |
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| non-spontaneous |
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| Cathode |
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| is the electrode where reduction takes place |
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| Anode |
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| is the electrode where oxidation takes place |
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| How to determine cathode from anode |
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| When the reactant is smaller on the product side, it is a cathode. |
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| Cell potential and free energy |
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| G=-nFE |
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| Faraday's constant C/mol(e-) |
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| 9.65 * 10^4 C/mol(e-) |
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| Faraday's constant e-/C |
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| 6.24 * 10^18 e-/C |
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| Cell potential |
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| E= (0.0592 V/n) * logK |
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| concentration cells |
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| uses effect of concentration changes on cell potential |
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| battery |
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| individual voltaic cells arranged in series, voltages add |
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| primary battery |
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| cannot be recharged ("dead" when the cell reaction reaches equilibrium) |
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| secondary battery |
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| rechargeable. Electrical energy is supplied to reverse the cell reaction |
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| silver button battery |
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| the mercury battery uses HgO as the oxidizing agent instead of Ag2O and has cell potential of 1.3 V |
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| lithium battery |
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| used in watches, implanted medical devices, and remote-control devices |
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| lead-acid battery |
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| the lead-acid car battery is a secondary battery (rechargeable) |
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| lithium-ion battery |
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| the secondary (rechargeable) lithium-ion battery is used to power laptops, and cell phones |
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| Fuel cell (flow cell) |
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| reactants enter the cell and products leave - reaction rates are lower than other batteries |
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| Electrocatalyst |
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| decreases activation energy |
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| Faraday's law of electrolysis |
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| amount of substance produced at each electrode is directly proportional to the quantity of charge flowing through the cell |
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| Electrolysis Stoichiometry |
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| Mass of substance x mol of substance x mol of e- x charge x current |
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| Electrolysis |
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| the splitting of a substance by the input of electrical energy |
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| When an (aq) salt solution is electrolyzed |
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| the strongest oxidizing agent is reduced, the strongest reducing agent is oxidized |
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| Overvoltage |
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| additional voltage needed to produce gases at metal electrodes |
