Final Flashcards
What is a Bronsted-Lowry Base?
a proton acceptor
What is a Bronsted-Lowry Acid?
proton donor
What does it mean to be amphiprotic?
a species that can either donate or accept an electron in a bronsted-lowry reaction
what does it mean to be amphoteric?
a species that can act as either an acid or a base
what is autoionization?
for water, the transfer of protons to yield hydronium and hydroxide ions
What is a buffer?
a mixture of appreciable amounts of a weak acid-base pair
it spH resists change when small amounts of acid or base are added
what is buffer capacity?
the amount of an acid or base that can be added to a volume of a buffer solution before its pH changes significantly
what is a conjugate acid?
a substance formed when a base gains a proton
what is a conjugate base?
a substance formed when an acid loses a proton
what is a diprotic acid/base?
an acid containing two ionizable hydrogen atoms per molecule
or
a base capable of accepting two protons
what is the levelling effect?
the strength of acid-base solutes in a given solvent is limited to the solvent’s characteristic acid and base species
in water, hydronium and hydroxide
what does a titration curve display?
pH vs volume of an added titrant
why does the neutralization reaction of a weak acid with a strong base give a weakly basic solution?
the salt ionizes the solution, but the anion slightly reacts with water to formulate a weak acid. The reaction also forms OH-, which then causes the solution to be basic.
what two assumptions can simplify calculations of equilibrium concentrations in a weak acid or base?
- Assume that the initial concentration of the acid is neglected, so this concentration can be assumed constant and equal to the initial value of the total acid concentration.
- Assume we can neglect the contribution of water to the equilibrium concentration of H3O+.
Explain why the pH does not change significantly when a small amount of an acid or a base is added to a solution that contains equal amounts of the acid H3PO4 and a salt of its conjugate base NaH2PO4.
Excess H3O+ is removed primarily by the reaction:
H3O+(𝑎𝑞) + H2PO4 (𝑎𝑞) ⟶ H3PO4(𝑎𝑞) + H2O(𝑙)
Excess base is removed by the reaction: OH−(𝑎𝑞) + H3PO4(𝑎𝑞) ⟶ H2PO4−(𝑎𝑞) + H2O(𝑙)
Explain how to choose the appropriate acid-base indicator for the titration of a weak base with a strong acid.
At the equivalence point in the titration of a weak base with a strong acid, the resulting solution is slightly acidic due to the presence of the conjugate acid. Thus, pick an indicator that changes colour in the acidic range and brackets the pH at the equivalence point. Methyl orange is a good example.
what is a salt?
an ionic solid that dissociates completely in water
define system
the part of the universe being studied
define surroundings
a part of the universe not being studied
anything that is not a part of the system
define universe
everything
system + surroundings = universe
define the enthalpy of formation
the enthalpy change of a chemical reaction in which 1 mole of a pure substance is formed from its elements in their most stable states under standard state conditions
what is specific heat capacity?
intensive property of a substance that represents the quantity of heat required to raise the temperature of 1 gram of the substance by 1 degree Celsius (or 1 kelvin)
what is pressure-volume work?
expansion work (or pressure-volume work) occurs when a system pushes back the surroundings against a restraining pressure, or when the surroundings compress the system.
what is internal energy?
the total energy of a system
U = Ek + Ep
what is entropy?
state function that is a measure of the matter and/or energy dispersal within a system, determined by the number of system microstates; often described as a measure of the disorder of the system
what is free energy? how does it relate to spontaneity, enthalpy and entropy?
what is spontaneity? how does it relate to free energy, enthalpy and entropy?
how can you alter spontaneity?
what is the first law of conservation of energy?
energy can be converted from one form to another, but cannot be created nor destroyed
What is energy?
the ability to do work (J)
what is kinetic energy?
energy due to motion (thermal energy )
what is potential energy?
energy due to position (stored energy)
what is temperature?
the measure of the average kinetic energy of atoms or molecules
the quantity that determines the direction of heat flow
measure of thermal energy in a system
what is thermal equilibrium?
what is heat?
what is an intensive property?
property of a substance that is independent of the amount of the substance
ie. density
what is an extensive property?
property of a substance that depends on the amount of the substance
what is a microstate (W)
A microstate is a specific configuration of all the locations and energies of the atoms or molecules that make up a system.
what is a state funtion
property depending only on the state of a system, and not the path that is taken to reach that state
ex. enthalpy
what is bomb calorimetry?
what is isobaric calorimetry?
is specific heat capacity intensive or extensive?
it is intensive
is heat capacity extensive or intensive?
it is extensuve
