Download Regents Chemistry Name KEY Unit 10 Kinetics Practice Test Using

Regents Chemistry
Unit 10 Kinetics Practice Test
Name KEY
Using your knowledge of Chemistry select the best answer, of those provided, to each question.
Record your answer in the space provided.
Given the equation representing a reaction:
N2O4(g) ↔ 2NO2(g)
_____1. Which statement describes this
reaction at equilibrium?
(1)The concentration of N2O4(g) must equal
the concentration of NO2(g).
(2)The concentration of N2O4(g) and the
concentration of NO2(g) must be constant.
(3) The rate of the forward reaction is greater
than the rate of the reverse reaction.
(4) The rate of the reverse reaction is greater
than the rate of the forward reaction.
Given the equation representing a reaction
at equilibrium:
H2(g) + I2(g) + heat ↔ 2HI(g)
_____2. Which change favors the reverse
reaction?
(1) decreasing the concentration of HI(g)
(2) decreasing the temperature
(3) increasing the concentration of I2(g)
(4) increasing the pressure
_____3. Which factors must be equal in a
reversible chemical reaction at equilibrium?
(1)the activation energies of the forward and
reverse reactions
(2) the rates of the forward and reverse
reactions
(3) the concentrations of the reactants and
products
(4) the potential energies of the reactants and
products
_____4. Systems in nature tend to undergo
changes toward
(1) lower energy and less disorder
(2) lower energy and more disorder
(3) higher energy and less disorder
(4) higher energy and more disorder
_____5.How is a chemical reaction affected
by the addition of a catalyst?
(1) The activation energy decreases.
(2) The heat of reaction increases.
(3) The number of collisions between particles
decreases.
(4) The potential energy of the reactants
increases.
_____6. Which 1-mole sample has the least
entropy?
(1) Br2(s) at 266 K
(3) Br2(l) at 332 K
(2) Br2(l) at 266 K
(4) Br2(g) at 332 K
Given the balanced equation representing a
reaction:
Cu + S → CuS + energy
_____7. Which statement explains why the
energy term is written to the right of the
arrow?
(1) The compound CuS is composed of two
metals.
(2) The compound CuS is composed of two
nonmetals.
(3) Energy is absorbed as the bonds in CuS
form.
(4) Energy is released as the bonds in CuS
form.
_____8. At 20.°C, a 1.2-gram sample of Mg
ribbon reacts rapidly with 10.0 milliliters of
1.0 M HCl(aq). Which change in conditions
would have caused the reaction to proceed
more slowly?
(1) increasing the initial temperature to 25°C
(2) decreasing the concentration of HCl(aq) to
0.1 M
(3) using 1.2 g of powdered Mg
(4) using 2.4 g of Mg ribbon
Given the balanced equation:
_____9. As the number of effective collisions
between reacting particles increases, the rate
of reaction
(1) decreases
(2) increases
(3) remains the same
Use the diagram below to answer question 13
which represent the changes in potential
energy that occur during the given reaction.
_____10. In most aqueous reactions, as
temperature increases, the effectiveness of
collisions between reacting particles
(1) increases
(2) decreases
(3) remains the same
The potential energy diagram below
represents a chemical reaction.
KNO3 (s) + 34.89 kJ
H2O
K+ (aq) + NO3- (aq)
_____12. Which statement best describes this
process?
(1) It is endothermic and entropy increases
(2) It is endothermic and entropy decreases
(3) It is exothermic and entropy increases
(4) It is exothermic and entropy decreases
Given the reaction: A + B → C.
_____13. What type of reaction is seen in the
diagram above?
(1) Exothermic because a single product is
formed
(2) Exothermic because the products have
more potential energy than the reactants.
(3) Endothermic because a single product is
formed.
(4) Endothermic because the products have
more potential energy than the reactants.
Given the reaction:
_____11. Which arrow represents the
activation energy of the forward reaction?
(1) A
(2) B
(3) C
(4) D
2 H2(g) + O2(g) → 2 H2O(l) + 571.6 kJ
_____14. What is the approximate ΔH for
the formation of 1 mole of H2O(l)?
(1) -285.8 kJ
(2) +285.8 kJ
(3) -571.6 kJ
(4) +571.6 kJ
Given the equation representing a phase change at equilibrium:
C2H5OH(l) ↔ C2H5OH(g)
_____15. Which statement is true?
(1) The forward process proceeds faster than the reverse process.
(2) The reverse process proceeds faster than the forward process.
(3) The forward and reverse processes proceed at the same rate.
(4) The forward and reverse processes both stop.
Part B: Complete all questions in this part of the test. Record your answers in the space provided.
Use the balanced equation below to answer question 16.
Ba(s) + CaCO3(aq) → Ca(s) + BaCO3(aq)
16. Explain, using information from Reference Table J, why this reaction is spontaneous. [2]
Ba is above Ca on Table J, Ba is more active than Ca therefore this reaction is spontaneous
17. Nitrogen gas, hydrogen gas, and ammonia gas are in equilibrium in a closed container at
constant temperature and pressure. The equation below represents this equilibrium.
N2(g) + 3H2(g) ↔ 2 NH3(g)
The graph below shows the initial concentration of each gas, the changes that occur as a result of
adding H2(g) to the system, and the final concentrations when equilibrium is re-established.
a.) What information on the graph indicates that the system
was initially at equilibrium? [1] The concentration remains
constant over the initial time
b.) Explain, in terms of LeChatelier’s principle, why the final
concentration of NH3(g) is greater than the initial
concentration of NH3(g). [1] H2 was added, this drives the
reaction to the right
Base your answers to questions 18 through 20 on the reaction represented by the balanced equation
below.
2H2(g) + O2(g) → 2H2O(l) + 571.6 kJ
18. Explain why the entropy of the system decreases as the reaction proceeds. [2]
Liquid water has less entropy than water vapor AND/OR there is a decrease in temperature.
19. Identify the information in this equation that indicates the reaction is exothermic. [1]
heat is on the product side of the equation. ∆H is negative.
20. If the amounts of H2 and O2 are both tripled, how much heat will be produced? [1]
3 x 571.6 kJ = 1714.8 kJ
Base your answers to questions 21 through 22 on the information and potential energy diagram
below.
Chemical cold packs are often used to reduce swelling after an athletic injury. The diagram
represents the potential energy changes when a cold pack is activated.
21. Which lettered interval on the diagram represents the
potential energy of the products? [1] D
22. Which lettered interval on the diagram represents the heat of
reaction?[1] C