Flashcards in General Chemistry Deck (52):
What is collision theory?
The rate of reaction is proportional to the number of collisions/second between reacting molecules. Considers each potential reaction to be "all-or-nothing" in term of energy.
What equation represents the rate of reaction?
A= frequency factor of collisions
What is the Ideal Gas Constant?
R= 0.0821 (L atm)/ (mol K)
R= 8.314 J/(mol K)
In an exergonic reaction delta G is ____ and energy is____.
negative; given off
In an endergonic reaction delta G is ___ and energy is ____.
What are homogenous catalysts?
Catalysts in the same phase as the reactants.
What are heterogenous catalysts?
Catalysts in a different phase as the reactants.
What is the rate law of zero-order reactions?
What is the rate law of first-order reactions?
rate= k(1/s) [A}
What is the rate law of second-order reactions?
rate= k(1/Ms) [A][B]
rate= k [A]^2
rate= k [B]^2
What is dynamic equilibrium?
rate of forward reaction=rate of reverse reaction; [R] and [P] remains constant
When will a reversible reaction reach equilibrium?
Entropy is maximized; Gibbs free energy is minimized
What is the equation for the law of mass action?
negative; forward since [R]>[P]
When Q>Keq, delta G is ___ and the reaction goes ___.
positive; reverse since [P]>[R]
When Q=Keq, delta G is ___ and the reaction goes ___.
0; at the same rate in both forward and reverse directions since [R] and [P] are at equilibrium proportions
If Keq>1, [P] is ____ [R] and delta G is ___.
greater than; negative (spont rxn)
If Keq<1, [P] is ____ [R].
less than (but reacted R IS NOT negligible)
If Keq<<<1, [P] is ____ [R] and delta G is ___.
extremely less than (reacted R IS negligible); positive (non spont rxn)
If you compress a system, what way will the reaction shift (according to Le Chatelier)?
To the side with the less # of gas mols. (increase P, increase mol, oppose)
If you expand a system, what way will the reaction shift (according to Le Chatelier)?
To the side with the more # of gas mols. (decrease P, decrease mol, oppose)
In an endothermic reaction, delta H is ____ and heat is a ____.
In an exothermic reaction, delta H is ____ and heat is a ____.
What is an isolated system?
A system where NOTHING is exchanged between system and surroundings.
What is a closed system?
A system where heat and work are exchanged between system and surroundings but NOT matter.
What is a open system?
A system where heat, work, AND matter are exchanged between the system and surroundings.
What is the first law of thermodynamics?
deltaU=Q(heat in)- W (work done by system)
What is the molar volume if an ideal gas at STP?
What is Avagadro's number?
6 x 10^23 molecules/mol
What is the equation for energy of a photon emitted by an atom moving from one energy state to another?
E= -Rh [(1/ni^2) - (1/nf^2)]
What is the value of Rh (Rydberg unit of energy)?
Rh= 2.18x10^-18 J/e-
Rh= 13.6 eV/e-
What is the value of h (Plank's constant)?
h= 6.26x10^-34 Js
What is the speed of light?
c=3 x 10^3 m/s
What is the conversion of J to eV?
1 eV= 1.6 x 10 ^-19 J
What is the formula for osmotic pressure?
What is shielding?
The electrons can't feel the pull of the nucleus due to all the other electrons shielding it.
substance made up of an array of repeating covalently bonded atoms
hard, very high melting points, and poor conductors
substance composed of metal atoms held together by metallic bonds
high melting points, ductile, good conductors
The first law of thermodynamics
energy cannot be created or destroyed
The second law of thermodynamics
the total entropy of an isolated system can never decrease over time
The third law of thermodynamics
as temperature goes down to 0 the entropy should be 0
What kinds of orbitals are favorable?
full, empty, and half-full
differ in the number of neutrons
substance made of positive and negative ions held together by electrostatic attractions.
very high melting points, brittle, poor conductors
Substance made of atoms or molecules held together by LDF, dipole-dipole forces, or hydrogen bonds (ex: sucrose)
low melting points, flexible, poor conductors
take electrons from another atom and is reduced
donate electrons to another atom and is oxidized
A more acidic molecule
has electron withdrawing groups that stabilize the conjugate base (strong acid--> weak/stable CB)
A less acidic molecule
has electron donating groups that destabilize the conjugate base
Keq of the reverse reaction
is equal to the inverse of the Keq of the forward reaction (and vice versa)
During phase changes...
there is not change in temperature (q=mL)