Equilibrium
What must be true about the forward and reverse reactions in a system at equilibrium?
They are equal.
Equilibriums must occur in what type of system?
Closed system.
Define temperature.
Average KE of all the particles in a sample of a material.
Energy is absorbed as bonds are broken. True or false?
True
Yes.
What is a stress? Give 3 examples.
Something that changes an equilibrium. Change in temp, concentration, or pressure.
How can you cause the rate of a reaction to increase for a chemical reaction?
Increase temp, increase surface area, increase concentration of reactants.
Explain how heat would transfer between a 40g block of solid zinc at 35 degrees C and a 35g block of solid steel at 50 degrees C that are in contact with each other.
The heat would transfer from the steel to zinc because the steel has more thermal energy and thermal energy transfers from high to low.
What is entropy
Randomness/disorder in systems.
How many sig figs in 2.034
4
What must be true about the concentrations of reactants and products in a system at equilibrium?
They must be constant. Not necessarily equal.
What is Le Chatlier's Principle?
Systems at equilibrium will shift to reduce the impact of a stress on that equilibrium.
The amount of energy needed to add to a solid sample of a material at it's melting point to cause a phase change.
Heat of fusion.
What does it mean for a reaction to be spontaneous?
The reaction can proceed without requiring an activation energy.
What is the difference between an ionic bond and a covalent bond.
Electrons are transferred/shared.
In the following reaction, predict what would happen if more of A was added.
A + B <--> C + energy
Equilibrium would shift right, away from stress.
Given the following reaction, describe what an increase in temperature would do to the rate of the forward reaction.
H2O (l) + energy <--> H2O (g)
Increase the rate.
Draw an energy graph for an exothermic reaction.
_-_
--/ \
\
\______________
What is collision theory?
States that reactions occur if and only if particles collide with proper orientation and proper energy.
What is the molecular formula for potassium oxide.
K2O
Suppose you want to make more NH3 using this reaction. How could you do that?
N2(g) + 3H2(g) --> 2NH3(g) + heat
Cool the system, add N2 or H2
Given the following reaction, state what would happen if pressure was increased and all other conditions were held constant?
N2(g) + 3H2(g) --> 2NH3(g) + heat
Reaction would shift to the right.
Draw an energy graph for an endothermic reaction and label the activation energy. Then draw what a catalyst would do.
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Systems in nature tend to shift towards __________ entropy and ________ energy
High, low
Explain how a neon sign works.
Electricity is run through a sample of neon causing some electrons enter the excited state and move up an energy level. Those electrons then drop back down to lower energy levels and release photons of energy that we see as neon light.