Module 1 and 2 Flashcards
K > Q which reaction is favoured
Forward
K < Q which reaction is favoured
Backward
Will a precipitate form if Q > K
Yes
Will a precipitate form if Q < K
No
The stronger the acid or base, the _____ the conjugate
Weaker
Ligands act as
Lewis bases
Acid base reactions involve the exchange of
1 proton
Redox reactions involve the exchange of
Electrons
“X is titrated with Y” (where are these solutions located)
X in flask (unknown concentration), Y in burette (known concentration)
Ratio of buffer made with weak acid or base and conjugate
1:1
Ratio of buffer made with weak acid/base and strong acid/base
2:1
Ionisation status depends on
pH of solution and pKa of functional group
Percent protonated when >1 unit below pKa
90%
Percent deprotonated when >1 unit above pKa
90%
Amino acid pKa below which all are protonated
2.5
Amino acid pKa above which all are deprotonated
9.5
𝚫fH
change in enthalpy for the formation of 1 mole of a compound from its constituent elements in their standard states (already in standard states= 0)
𝚫vapH
change in enthalpy for one mole of a substance changing from a liquid to a gas
𝚫fusH
change in enthalpy for one mole of a substance changing from a solid to a liquid
𝚫comH
change in enthalpy for the combustion of one mole of a substance in oxygen (products CO2, H2O)
Negative change in enthalpy
Exothermic
Positive change in enthalpy
Endothermic
Spontaneous meaning
Once started continues without help, not necessarily to completion
Standard entropy conditions
1molL^-1, 1 bar pressure, no value for temperature
Positive Gibbs energy
Non spontaneous under standard conditions
Negative Gibbs energy
Spontaneous under standard conditions
Gibbs energy = 0
Equilibrium
What does the magnitude of G tell us
How far a reaction will go to completion (no absolute value of G)
𝚫fG for a pure element
0
Units for enthalpy
kJmol^-1
Units for entropy
JK^-1mol^-1
Positive enthalpy and entropy
Spontaneous at high temperatures
Negative entropy, negative enthalpy
Spontaneous at low temperatures
Positive entropy, negative enthalpy
Spontaneous at all temperatures
Negative entropy, positive enthalpy
Non spontaneous at all temperatures
Units of k 0th order
molL^-1s^-1
Units of k 1st order
s^-1
Units of k 2nd order
Lmol^-1s^-1
Units of k 3rd order
L^2mol^-2s^-1
What is a pseudo first order reaction
[B]»_space; [A], when [B] changes [A] doesn’t change much
Unit for rate
molL^-1s^-1
What is Ea
Energy difference between reactant and highest energy transition state
Straight line Arrhenius equation rearrangement
lnk = -Ea/R 1/T + lnA
When can you use the integrated rate law
Only for first order reactions
The rate doubles for every ___ increase in temperature
10C
E standard will always be _____ for a spontaneous reaction
Positive
The smaller the Ka or Kb, the _____ the acid or base
Weaker
The larger the pKa or pKb, the _____ the acid or base
Weaker
The larger the Ka or Kb, the _____ the acid or base
Stronger
The smaller the pKa or pKb, the _____ the acid or base
Stronger
Ligand definition
Molecule or ion in which one or more donor atoms have a lone pair of electrons (biologically important donor atoms: N, O, P, S) (an ion or molecule attached to a metal atom by coordinate bonding.)
Ligands act as
Lewis bases (donate electrons to transitional metal ion)
When water is the ligand, resulting complex can act as
Weak base
Ligand complex becomes more acidic as
Charge on cation increases
What doesn’t appear in Kc expressions
Pure solids AND liquids
The _____ the acid or base, the ______ the conjugate
Stronger, weaker
Straight line axes for linear first order reaction
ln[X] vs t
Arrhenius equation
K = Ae^-Ea/RT