Quiz On Equilibrium And Kinetics Answer Sheet Part I B
CLEANED: Quiz Equilibrium And Kinetics Answer Sheet Part I Brief Res
Briefly and completely answer each question related to equilibrium and kinetics based on the provided scenarios and concepts. Focus on understanding reaction rates, surface area effects, equilibrium constants, and the effects of changing conditions on chemical systems. Include explanation and reasoning for each answer, and support with relevant scientific principles and examples.
Paper For Above instruction
Introduction
The study of equilibrium and kinetics is fundamental in understanding how chemical reactions proceed and reach their stability. These principles are crucial in industrial applications, biological systems, and environmental processes. This paper addresses various questions on reaction rates, surface area influence, equilibrium constants, and the effects of temperature, pressure, and catalysts, supporting answers with scientific reasoning and examples.
Part I: Short Response Questions
1. Which trial would produce the fastest reaction?
The trial expected to produce the fastest reaction is Trial D, which features small particle size, higher HCl concentration (2 M), and higher temperature (40 ºC). Reaction rate is influenced by surface area, concentration, and temperature, with smaller particles offering greater surface area for reaction, higher concentrations increasing collision frequency, and higher temperature providing more energy to overcome activation barriers.
2. Which two trials could be used to measure the effect of surface area?
Trials A and B are suitable for assessing surface area effects because they involve the same concentration and temperature, differing only in particle size (small vs. large). The comparison isolates surface area as the variable affecting reaction rate.
3. What is the name for the energy needed to start a chemical reaction?
Activation energy (Ea) is the energy barrier that must be overcome for reactants to form products in a chemical reaction.
4. A reaction is most likely to occur when reactant particles collide with
Reactant particles collide with sufficient energy (equal to or greater than activation energy) and proper orientation for reactions to occur.
5. Joey put 100 mL of HCl into four bakers under different conditions. Which beaker will have the fastest reaction with a magnesium strip? Why?
The beaker with the highest concentration of HCl (2 M) at the highest temperature (40 ºC) will have the fastest reaction because increased concentration and temperature increase collision frequency and energy.
6. Which equilibrium constant indicates the highest concentration of product? Explain.
Option D, K = 4, indicates the highest concentration of product because a larger K value means the equilibrium favors product formation more strongly.
7. For the reaction H₂(g) + Br₂(g) ⇌ 2 HBr(g), what is the relationship between the forward and reverse rates?
At equilibrium, the rate of the forward reaction equals the rate of the reverse reaction, maintaining constant concentrations of reactants and products.
8. Which is the equilibrium expression for the reaction 2CO(g) + O₂(g) ⇌ 2 CO₂(g)?
K = [CO₂]² / ([CO]² [O₂])
9. Which chemical equation corresponds to the given equilibrium expression? 2/3 [A] / [B] [C] K = 10.
This suggests a proportional relationship where the product of concentrations of B and C relates to the concentration of A raised to a power, consistent with the equilibrium expression for a reaction such as A ⇌ B + C.
10. Considering the reaction 2H₂(g) + O₂(g) ⇌ 2H₂O(g) + heat, if pressure increases due to volume decrease, what is the effect on [O₂]? Explain.
Increasing pressure (reducing volume) will increase all gaseous concentrations, including [O₂], because the total number of molecules remains constant or the reaction shifts to counteract pressure changes, often favoring side with fewer moles (here, possibly troubleshooting depending on equilibrium shift).
11. For the reaction 2A(g) + 3 B(g) ⇌ A₂B₃(g) + heat, what change will not affect the concentrations? Why?
Option B, adding a catalyst, will not change concentrations because catalysts only affect reaction rate, not equilibrium position.
12. For N₂(g) + O₂(g) + energy ⇌ 2 NO(g), which change decreases NO?
Option C, decreasing N₂ concentration, will decrease NO because it reduces the reactant pool and shifts equilibrium leftward.
Part II: Extended Response
13. Equilibrium expressions for reactions
a. For 2H₂O(g) + 4KO₂(s) ⇌ 4KOH(s) + 3O₂(g), the equilibrium expression is: K = [O₂]³, since pure solids are omitted.
b. For CuO(s) + H₂(g) ⇌ Cu(l) + H₂O(g), the expression is: K = [H₂O], as solids are omitted and only gases and liquids are included.
14. For 2HBr(g) ⇌ Br₂(g) + H₂(g), K = 6.45 × 10⁻⁴. Which side is favored?
Since K
15. N₂(g) + 2O₂(g) ⇌ 2NO₂(g).
Analysis of equilibrium constant and reaction conditions reveals that increasing temperature or decreasing pressure shifts favorability toward the reactants or products depending on the reaction’s entropy change; in this case, increasing temperature favors the endothermic formation of NO₂.
16. Calculation of parameters at equilibrium
Given the concentrations, the equilibrium constant K can be calculated, and the concentration of N₂ at equilibrium can be derived accordingly, following the law of mass action.
17. Effect of changes on O₂ concentration
a. Water addition: The concentration of O₂ remains unchanged as water does not directly affect oxygen gas.
b. Temperature decrease: Decreases reaction rate and possibly shifts equilibrium to form more O₂ if the reaction is exothermic.
c. Removing H₂: The equilibrium shifts to produce more H₂O, affecting O₂ concentration depending on the shift direction.
18. Changes in collisions and reaction rate
a. Decreasing concentration reduces collisions and reaction rate.
b. Increasing temperature increases collision energy and frequency, raising reaction rate.
c. Increasing volume decreases particle collisions, reducing reaction rate.
d. Decreasing volume increases collision frequency, raising reaction rate.
e. Adding a catalyst increases collision efficiency, enhancing reaction rate without changing collision number.
19. Equilibrium constant of reverse reaction: 2HOCl(g) ⇌ Cl₂O(g) + H₂O(g)
The inverse of the original, so K = 1 / 0.0090 ≈ 111.11. For the reaction 2 Cl₂O + 2 H₂O ⇌ 4 HOCl, K is (0.0090)² = 8.1 × 10⁻⁵.
20. Is the reaction at equilibrium and shifts?
Calculating the reaction quotient (Q) and comparing to K determines if the system is at equilibrium. If Q ≠ K, the reaction will shift toward the side that restores equilibrium, either producing more N₂ or consuming some, depending on the comparison.
Conclusion
This comprehensive review of equilibrium and kinetics covers reaction rates, factors influencing reactions, equilibrium constants, and the effects of changing conditions on chemical systems. Understanding these principles enables better control and prediction of chemical processes across scientific disciplines.
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