Flashcards in Chapter 7 Deck (50):
What two things play an important role in determining the extent and speed of a chemical reaction?
1) Thermodynamics, which deals with energy changes in chemical reactions
2) Kinetics, which describes the rate or speed of a chemical reaction
study of energy, work, and heat
3 Basic laws of thermodynamics?
1) energy cannot be created or destroyed, only converted from one form to another
2)the universe spontaneously tends toward increasing disorder or randomness
3)the disorder of a pure, perfect crystal at absolute zero is zero 0 (Kelvin)
Average kinetic energy of atoms or molecules does what with increasing temperature?
What happens when some collisions of molecules occur with sufficient energy?
can break bonds in molecules
What can happen when a reactant bond is broken?
new bonds may be formed and products result
contains the process under study
encompass the rest of the universe (system)
transfer of thermal energy to the surroundings; sometimes consider heat flow
Experimental strategies for measuring temperature change and calculating heats of reactions
Releases energy to the surroundings (surroundings become warmer)
representative with a negative sign
absorbs energy from the surrounds (surrounding become colder)
representative with a positive sign
term used to represent heat and is symbolized as H
If H reactants > H products, what is H?
H must be negative and the reaction is exothermic
If H reactants < H products, what is H?
H must be positive and the reaction is endothermic
A measure of the randomness of a chemical system.
Symbol for entropy?
symbol G, represents the combined contribution of the enthalpy and entropy values for a chemical reaction
4 situations of G
-H (neg) & S (pos), G is always pos, regardless of temp
-H (pos) & S (neg), G is always neg, regardless of temp
-H (pos) & S (neg), G depends on temp
-H (neg) & S (neg), G depends on temp
number of calories (cal) of heat needed to raise the temperature of 1 gram (g) of the substance 1 degree Celsius (c).
Quantity of heat absorbed or released by the reaction (Q)?
mass of solution in the calorimeter (Ms), (X)
specific heat of the solution (SHs), (X)
change in temperature (Ts) of the solution
is the amount of energy per g of food
Nutritional Calories (Cal)
equivalent to one kilo-calorie (1000 cal), known as the large Calorie
measurement of the fuel value (Cal) of foods
producing product molecules (requires sufficient energy and, in the case of complex molecules, the proper orientation of reaction molecules.
Ea, minimum amount of energy required to initiate a chemical reaction
reaction proceeds from reactants to products through an extremely unstable state
Factors that affect reaction rate
1) structure of the reacting species
2) molecular shape and orientation
3) the concentration of reactants
4) the temperature of reactants
5) the physical state of reactants
6) the presence of a catalyst
substance that increases the reaction rate
rate constant @ specific temp
rate being equal to the rate constant multiplied by the reactant concentration raised to an exponent
reactions that do not go to completion. no further obvious change is taking place, measurable quantities of reactants and products remain
process that can occur in both directions
situation in which the rate of the forward process in a reversible reaction is exactly balanced by the rate of the reverse process
Keq = products/reactants
Is Keq temp dependent or not?
what temp is equilibrium constant reported at?
25 degree C
if a stress is placed on a system at equilibrium, the system will respond by altering the equilibrium composition in such a way to minimize the stress
Add product, equilibrium shifts to the ?
Add reactant, equilibrium shifts to the ?
N2(g) + 3H2 (G) 2NH3 (g) + kcall is a what reaction?
How does equilibrium shift when heat is added to exothermic reaction?
will shift left
How does equilibrium shift when heat is removed from an exothermic reaction?
will shift right
How does equilibrium shift when heat is added to endothermic reaction?
will shift right
How does equilibrium shift when heat is removed from an endothermic reaction?
will shift left
39 kcal + 2N2(g) + O2(g) 2N2O(g) is what type of reaction?
Pressure on an equilibrium reaction does what to reaction
shifts to the side that has the least amount of mole
pressure released on an equilibrium reaction does what to the reaction
shifts to the side that has the most amount of moles