Chapter 10 CHEMISTRY
P4(s)+5O2(g)⇌P4O10(s)
Kc=1/[O2]^5
2Fe2O3(s)+3C(s)⇌4Fe(s)+3CO2(g)
Kc=[CO2]^3
Find the equilibrium expression for the reversible reaction below. 2CO2(g)⇌2CO(g)+O2(g)
Kc=[CO]^2[O2] --------------- [CO2]^2
What is the equilibrium constant for the reversible reaction shown below? N2(g)+3H2(g)⇌2NH3(g)
Kc=[NH3]^2 --------- [N2][H2]^3
The rate at which a reaction is proceeding at a specific point in time is called the:
instantaneous rate
Which is an example of the state of subdivision of the reactants affecting the rate of reaction?
large pieces of iron react slowly with acids while finely divided iron reacts more rapidly
The first postulate of collision theory states that the rate of a reaction is _______ to the rate of reactant collisions.
proportional
A catalyst lowers the activation energy of a reaction by:
providing an alternate pathway or mechanism
How will increasing the temperature by ten degrees Celsius impact the rate of reaction?
depends on the reaction
Which of the following are postulates of collision theory?
-The rate of a reaction is proportional to the rate of effective reactant collisions. -The reacting species must collide with the optimal orientation to allow the appropriate bonds to break and/or form as reactants are converted to products. -The collision must occur with adequate energy to permit mutual penetration of the reacting species' valence shells so that the electrons can rearrange and form new bonds.
Which is an example of concentration affecting the rate of reaction?
A reaction slows down as it proceeds.
Of the following, which is a false statement regarding chemical equilibrium?
A reversible reaction means a reaction that is at equilibrium between reactants and products.
Which description best fits the definition of activated complex?
An activated complex is an unstable combination of reactant species representing the highest energy state of a reaction system.
Which of the following react relatively slowly (hours to years) rather than nearly instantaneously? (select all that apply)
An egg spoiling in a freezer Calcium exposed to water Iron train tracks exposed to the air
Of the following, which are TRUE about collision theory? (select all that apply)
Collision theory explains why reaction rates tend to increase with higher concentrations. Collision theory states that, in addition to a collision in the proper orientation, adequate activation energy is required for a reaction to occur. Collision theory explains that more frequent collisions lead to a faster reaction rate.
Identify the options below that are false about chemical equilibria. (select all that apply)
Concentrations of products and reactants oscillate between a set range of values. At equilibrium, all species have stopped reacting altogether.
Of the following, which are true of chemical equilibria? (select all that apply)
Correct answer: The reaction proceeds in the forward and reverse directions simultaneously. The forward and reverse reactions occur at equal rates.
The rate at which a reaction proceeds when the reaction first commences is called the:
Correct answer: initial rate
Choose the options below that are true of chemical equilibria. (select all that apply)
The reaction proceeds in the forward and reverse directions at the same rate. Both the forward and the reverse reactions are achievable. There is no net change in concentrations of reactants and products.
Which of the following is an unstable combination of reactant species representing the highest energy state of a reaction system?
activated complex
The conductivity of the solution in a reaction can be used to measure rates of reactions involving:
aqueous electrolytes
Which is an example of the chemical nature of substances affecting the rate of reaction?
calcium reacts with water moderately, sodium can react explosively with water
K is always __________.
dependent on the reaction
As a reaction proceeds in the forward direction, K will:
increase
A rate expression for any reactant in a chemical reaction will always be:
negative
Which of the following is a postulate of Collision Theory? 1. none of the above 2. The rate of a reaction is equal to the rate of collisions. 3.The reactants can collide in any orientation with no effect on the likelihood of the reaction. 4. Collisions must occur below a maximum energy in order to lead to reactions.
none of the above
Which is an example of the chemical nature of substances affecting the rate of reaction?
sodium oxidizes overnight whereas iron takes much longer
Kc expressions will exclude:
solids
The orientation of the molecules in a collision must allow for contact between:
the atoms that will be bonded to one another in the product
Which of the following is true about the rate expressions in a chemical reaction?
the rate expression for any product will be positive, and that for any reactant will be negative
Which is an example of the state of subdivision of the reactants affecting the rate of reaction?
the smaller the piece of wood, the faster it burns
Why do collisions have to have more kinetic energy than the activation energy of the reaction in order for the reaction to proceed?
the valence shells of the colliding atoms must achieve mutual penetration
As the activation energy is reached, what type of complex is generated?
transition state
The structure in a reaction that has the highest potential energy is the:
transition state
The transition state of a reaction can easily be isolated:
under no circumstance
When is the average rate of a reaction equal to its instantaneous rate at a given second?
when the reaction proceeds at a constant rate