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What is a solute?
Normally the component present in the smaller amount.
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What is a solvent?
The dissolving medium, normally the component present in the larger amount.
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What is molality?
moles solute/ kilograms of solvent.
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What is molarity?
moles solute/liters of solution
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What does parts per million mean? (ppm)
A concentration of 1 ppm means that every million grams of solution contain 1 g of solute.
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What is the dilution equation?
MiVi = MfVf
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What is electrical conductivity governed by, in the case of aqueous solution?
It is governed by the presence and concentration of ions in solution.
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What are electrolytes?
Solutes whose solutions are conductive.
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When is a solute considered a strong electrolyte?
If it dissociates completely into its constituent ions.
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What are examples of strong electrolytes?
NaCl and KI and molecular compounds with highly polar covalent bonds that dissociate into ions when dissolved like HCL in water.
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What does a weak electrolyte do in aqueous solutions?
It ionizes or hydrolyzes incompletely in aqueous solution and only some of the solute is present in ionic form.
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What are examples of weak electrolytes?
Acetic acid and other weak acids, ammonia and other weak bases and HgCl2.
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What are nonelectrolytes?
Compounds that do not ionize at all in aqueous solution, retaining their molecular structure in solution.
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What are examples of nonelectrolytes?
Nonpolar gases and organic compounds such as oxygen and sugar.
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What are colligative properties?
The presence of solute particles can make the physical properties of a solution different from those of the pure solvent.
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What is vapor pressure?
the pressure of the vapor above a fluid due to evaporated molecules.
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WHen does a liquid boil?
When its vapor pressure is equal to the ambient pressure.
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Which is higher, the boiling point of a solution or the boiling point of a pure solvent?
The boiling point of a solution is higher than that of the pure solvent.
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What happens to the freezing point of a liquid with the addition of solute?
The freezing point of a liquid decreases with the addition of solute.
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What is the definition of osmotic pressure?
The pressure that would have to be applied to a solution to prevent diffusion of pure solvent through a semipermeable membrane into that solution.
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What is the equation for osmotic pressure?
pi = MRT
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What is reduction?
The gain of electrons (RIG)
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What is oxidation?
Loss of elections (OIL)
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Describe the oxidizing agent?
It gets reduced and oxidizes something else.
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Describe the reducing agent.
It gets oxidized; reduces something else.
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What is the oxidation number of an element in its elemental form?
0
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What is the oxidation state of a monatomic ion?
The same as its charge.
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How do you assign oxidation numbers based on periodic trends?
alkali metals (group 1): +1, alkaline earth metals (group 2): +2, etc.
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What are the two types of electrochemical cells?
Galvanic cells and electrolytic cells.
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What is the anode and cathode?
The anode is the site where oxidation occurs. The cathode is where reduction occurs.
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What is a salt bridge?
It dissipates the presences of a charge gradient and it permits the exchange of cations and anions. They contain an inert electrolyte
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Describe electrolytic cells.
Has a positive DG and is nonspontaneous. Electrical energy is required to induce the reaction.
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Describe Galvanic cells.
They have a negative DG and are spontaneous and are used to do work.
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Where does oxidation and reduction occur?
Oxidation at the anode; reduction at the cathode. (An Ox, Red cat)
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How do electrons flow (talking about electrodes)?
Electrons flow through the wire from anode to cathode.
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What is the reduction potential?
The tendency of a species to acquire electrons and be reduced. The more positive the potential, the greater the species' tendency to be reduced.
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What can we determine from the reduction potential of a species?
THe species in a reaction that will be oxidized or reduced can be determined from the reduction potential of each species.
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What can we learn from the following:
F2 (g) + 2e- --> 2F- (aq) Ei red = +2.87 V
F2(g) likes to be reduced (since it has a large, positive Eired) and is therefore a strong oxidizing agent.
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What can we learn from the following equation:
Li+ (aq) + e- --> Li(s) Eired = -3.05 V
Li+ doesn't like to undergo reduction (it has a large, negative Eired).
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What can we learn from the following equation: Li(s) --> Li+ (aq) + e- Eiox= +3.05
Li didn't like to undergo reduction (large, negative Eired) but flipping the equation, means flipping the signs. Therefore, Li(s) likes to undergo oxidation and is therefore, a strong reducting agent.
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What is used to calculate the standard electromotive force (EMF)?
Standard reduction potentials.
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What is the equation for EMF?
EMF = Eored + Eoox
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What are the signs of standard EMF's of a galvanic and electrolytic cell?
The standard EMF of a galvanic cell is positive while the standard EMF of an electrolytic cell is negative.
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What are the three definitions of acids and bases?
Arrhenius, Bronsted-Lowry and Lewis.
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Describe the Arrhenius definition of acid/base.
An acid is a species that produces H+ (protons) in an aqueous solution, a base produces OH- in an aqueous solution.
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What is the Bronsted-Lowry definition of acid/base?
An acid is a species that donates protons, while a Bronsted-Lowry base is a species that accpets protons.
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What is an example of a Bronsted-Lowry base but not an Arrhenius base?
NH3 and Cl-
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What is the Lewis definition of an acid and base?
An acid is an electron-pair acceptor, and a base is an electron-pair donor.
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Is H2O an acid or a base?
It's both; It's either a proton donor or an acceptor toward itself (amphoteric).
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What is Keq for water?
Keq= Kw= [H3O][OH-] = 1 x 10-14
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What is the pH?
pH = -log[H] = log(1/[H])
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What pH's are considered neutral, acidic and basic?
acidic = less than 7, basic = greater than 7 and neutral = 7.
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What are some examples of strong acids?
HClO4, HNO3, H2SO4, HCl, HBr and HI.
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What are some examples of strong bases?
NaOH, KOH, and other soluble hydroxides of Group IA and IIA metals
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What are weak acids and bases?
They do not ionize completely and are weak electrolytes. They only partially dissociate in aqueous solution.
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What is a dissociation constant?
Ka- a measure of the degree to which an acid dissociates.
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What is the general equation for the acid dissociation constant?
Ka= [H3O+][A-]/ [HA]
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What is a titration?
It involves the addition of a solution to determine its concentration.
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What occurs at the equivalence point?
the number of moles added equals the number of moles of acid intitailly present.
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What is the equation for the equivalence point?
VaMa = VbMb
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