CH7 Unit 4
Card Set Information
CH7 Unit 4
chem 107 chapter unit
energy rate and equilibrium
the study of energy, work and heat
the law of ___ help us to understand why some chemical reactions occur and others do not
contains the process under study
the rest of the universe
___ ___ for energy stored in a chemical system cannot be measured
can measure the ___ ___ ___ during these chemical changes
change in energy
breaking of bonds means?
forming bonds means?
give off energy
first law of thermodynamics?
energy of the universe is constant
AB + CD ->?
AD + CB
if a reaction will occur?
bonds must break
breaking bonds requires energy
energy is a product in this reaction
+in an exothermic reaction ( AB +CD-> AD + CB) what happens to the reactants? what happens to the products?
the bonds must be broken, requiring energy
the bonds are formed, releasing energy
in an exothermic reaction, where is the heat?
in the product
in an endothermic reaction, where is the heat?
in the reactants
represents heat energy
what reduces activation energy?
is exothermic negative or positive?
negative delta H
is endothermic negative or positive?
positive delta H
energy released, enthalpy is?
energy absorbed, enthalpy is?
sign for enthalpy?
add energy to make it go from A to B in a reaction
endothermic (+delta H)
occurs without an external energy input
most exothermic reactions are?
what is used to help predict is a reaction will occur?
gibbs free energy equation?
delta G = delta H - delta S (entropy)
measure of disorder
entropy( delta s)
a measure of the randomness of a chemical system
the universe spontaneously tends toward increasing disorder or randomness
the second law of thermodynamics
highly disordered system, the absence of a regular, repeating pattern
well organized system such as a crystalline structure
there is not such thing as negative
entropy reaction formula?
delta S = S(products) - S (reactants)
a positive entropy means?
an increase in disorder for the reaction
a negative entropy means?
a decrease in disorder for the reaction
(goes toward more order)
processes having positive entropy?
represents the combined contribution of the enthalpy and entropy values for a chemical reaction
free energy (delta G)
what does free energy predict?
spontaneity of chemical reactions
negative free energy?
positive free energy?
if exothermic and positive entropy?
if endothermic and negative entropy?
need to know both ___ and ___ to predict the sign of free energy
___ also may determine direction of spontaneity
the measurement of heat energy changes in a chemical reaction
device which measures heat changes in calories
the change in temperature is used to measure the?
loss or gain of heat
the number of calories of heat needed to raise the temperature of 1gof the substance 1 degrees C
what do you need to determine heat released or absorbed?
total number of grams of solution
if heat is absorbed it is ?
1000 cal = __ kcal = __ Cal
C (capital c)
used to measure nutritional Calories
the study of the rate of chemical reactions
determines if a reaction will occur spontaneously, but tells us nothing about the amount of time the reaction will take
represents changes over time
the rate of ___ ___ can aid in calculating the rate of the chemical reaction
one that produces product molecules
___ is required to break bonds
the minimum amount of energy required to initiate a chemical reaction
an extremely unstable, short lived intermediate complex
factors that affect reaction rate?
shape and orientation
presense of a catalyst
___ charged species react more rapidly
ions with the same charge?
do not react
magnitude of the activation energy is related to?
rate will generally ____ as concentration ___
rate ___ as temperature ____
a higher percentage of these collisions will result in product formation
higher kinetic energy
a substance that increases the reaction rate
a ___ interacts with the reactants to create an alternative pathway for product production
atoms, ions, compounds are close together but restricted in motion
particles are free to move but often are far apart causing collisions to be relatively infrequent
particles are free to move and are in close proximity
reactions are ____ in the liquid state and ____ in the solid state
in a rate equation, used?
this type of reaction has a double arrow
equilibrium reactions are also called
ex of physical equilibrium?
sugar dissolved in water
dissolved oxygen in lake water
a process that can occur in both directions
the rate of the forward process in a reversible reaction is exactly balanced by the rate of the reverse process
if you increase the pressure, it drives the equilibrium to side with
in the dynamic equilibrium, rate forward=
never include what in a concentration ?
solids or liquids
if keq is very large, tan you have?
lots of products
if keq is very small, then you have?
lots of reactants
means the equilibrium will be disturbed
if a stress is placed on a system at equilibrium, the system will respond by altering the equilibrium composition in such a way as to minimize the stress
to relieve stress,?
remove as much of added material as possible by converting it to reactants
product introduced, equilibrium shifts to?
reactant introduced, equilibrium shifts to?
treat heat as a product
treat heat as a reactant
affects the equilbirum only if one or more substances in the reaction are gases
when pressure goes up, shift to side with?
less moles of gas
when pressure goes down, shift to side with?
more moles of gas
has no effect on the equilibrium composition