General Chemistry
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For the following certain single-step reaction represented by P + Q ⇌ R + S, Derive a relationship between the equilibrium constant and the rate constants of the forward and reverse reaction.
Describe what happens to the rate of the reaction when chemical equilibrium is achieved.
A hypothetical reversible reaction M → N is represented by the following five figures. Blue spheres represent M while yellow spheres represent N. The progress of the reaction is depicted by the figures from left to right. Does the reaction reach equilibrium in any of the figures? If so, which figure(s) show the system in equilibrium?
Which of the following figures represent chemical equilibrium?
Choose the statement that correctly describes the concept of chemical equilibrium
Which of the following statements about chemical equilibrium are true?
Consider the following reaction is carried out at constant volume:
CaCO3(s) ⇌ CaO(s) + CO2(g)
An equilibrium state can be achieved if one of these conditions are met:
Identify the reaction which does not show a homogenous equilibrium.
In a system wherein the liquid and the vapor are in equilibrium, the pressure that the vapor is exerting on the liquid is called the vapor pressure. Write a reaction equation to represent the equilibrium between liquid methanol and methanol vapor and provide the Kp expression for the reaction.
Write the equilibrium constant expressions for Kc and Kp of the reversible reaction:
2 FeS (s) + 3 O2 (g) ⇌ 2 FeO (l) + 2 SO2 (g)
The equilibrium constant, Kc, for the single-step reaction X(g) + Y(g) ⇌ XY(g) is 3.0×103. Which one of the following is true?
Propane undergoes thermal cracking for light olefin production. One of two thermal decomposition reactions that occur in a reactor is shown below. Write the equilibrium constant expressions Kp and Kc for the reaction.
C3H8 (g) ⇌ C2H4 (g) + CH4 (g)
The equilibrium state for the reaction X2 + Y2 ⇌ 2 XY is depicted in the following image.
Which rate constant, kr or kf, is bigger? Explain.
Compare the rate constants for the forward (kf) and the reverse (kr) reaction if the mixture contains a low concentration of reactants and a large concentration of products.
The rates of the forward and reverse reaction of A + B2 ⇌ AB2 are 15 M/s and 9 M/s respectively. In which direction will the reaction proceed to reach equilibrium?
Identify which gives a comparable concentration of products and reactants at equilibrium.
For the given reaction, provide the Kc expression and determine if it is homogenous or heterogenous:
2 Hg(l) + O2(g) ⇌ 2 HgO(s)
I2(s) + Cl2(g) ⇌ 2 ICl(g)
H2(g) + I2(g) ⇌ 2 HI(g)
Identify the following statement as correct or incorrect: A small value of the equilibrium constant indicates that the rate of the reverse reaction is greater than the rate of the forward reaction.
For the following reaction, determine which direction the reaction lies and identify if it is reactant-favored or product favored.
H2(g) + I2(g) ⇌ 2 HI(g) Kc = 50.5
Consider the following reaction: Cu+(aq) + 2 I–(aq) ⇌ [CuI2]–(aq), K = 8.0×108. Determine whether the forward or reverse reaction has a larger rate constant assuming that both reactions are elementary reactions.
Identify the incorrect statement.
Identify the correct K expression for the reaction 2 NO(g) + 2 H2(g) ⇌ N2(g) + 2 H2O(l)
Provide the K expression for the following reaction: SnO2(s) + 2 CO(g) ⇌ Sn(s) + 2 CO2(g)
Provide the K expression for the following reaction: 4 CuO(s) + CH4(g) ⇌ CO2(g) + 4 Cu(s) + 2 H2O(g)
For each equilibrium constant, identify if the reactants or products are favored.
i. K = 1.983ii. K = 5.38 × 10–2
The reaction of chlorine gas (Cl2) with a slurry of calcium hydroxide ((Ca(OH)2) produces calcium oxychloride (). The reaction takes place according the following chemical equation:
Ca(OH)2(s) + Cl2(g) ⇌ Ca(OCl)2(aq) + H2O(l)
Write an expression for the equilibrium constant (Kc) for this reaction.
Which of the following statements is correct for the following reaction:
NO2(g) + NO3(g) ⇌ N2O5(g) K= 2.1x10-20
Which of the following statements is true for a chemical reaction for which the value of equilibrium constant (K) is too large (K >> 1)?
Identify the expression for Kc for the following reaction: Ti(s) + 2 Cl2(g) ⇌ TiCl4(l)
Consider the following equilibrium:
H2O(l) ⇌ H2O(g)
At 70°C, what is the value of Kp for this reaction?
The vapor pressure of any liquid and the pressure exerted by its vapor are equal when the two are in equilibrium. Determine the value of Kp at the normal boiling point of a liquid in equilibrium with its vapor.
The equilibrium constant for the following decomposition reaction at 75.0 °C is 2.73.
NH3BF3(s) ⇌ NH3(g) + BF3(g)
What is the minimum amount of NH3BF3(s) in grams that has to be added to a 0.350 L flask in order to reach equilibrium?
What are the equilibrium concentrations of NH3 and BF3 if a sample of NH3BF3(s) is put inside a closed container at 75.0 °C and allowed to reach equilibrium?
The equilibrium constant for the following decomposition reaction at 212 °C is 1.20.
Ca(OCl)2(s) → Ca(s) + Cl2(g) + O2(g)
What are the equilibrium concentrations of Cl2 and O2 if a sample of Ca(OCl)2(s) is put inside a closed container at 212 °C and allowed to reach equilibrium?
For the reaction A + X ⇌ B, where X = C (blue), D (orange), or E (grey), refer to the three images below showing the reaction at equilibrium at the same temperature. Arrange Keq for the three reactions from smallest to largest.
A dry ice container with a capacity of 20.0 US liquid quarts was used to hold cylindrical dry ice pellets. Assuming that each pure cylindrical dry ice pellet has a density of 1.6 g/cm3, a diameter of 1.6 cm, and a length of 6.0 cm, find the number of pellets required to saturate the container with gaseous carbon dioxide. The equilibrium constant Kc for the sublimation of carbon dioxide is 1889.2.
CO2 (s) ⇌ CO2 (g)
Like naphthalene balls, 1,4-Dichlorobenzene (para-dichlorobenzene) balls are used to kill moth larvae by their slight sublimation at room temperature. A reasonable amount of these were left exposed in a 5.0 m by 5.0 m by 5.0 m room at 25 °C. Assuming that these spheres are pure solid para-dichlorobenzene and that the Kc value for the sublimation reaction is 2.72×10−13 at 25 °C, determine the number of gaseous para-dichlorobenzene molecules present in the room at equilibrium.
C6H4Cl2 (s) ⇌ C6H4Cl2 (g)
Nitrogen and hydrogen combine to form ammonia. The Kp of the reaction at 25 °C is 1.4×10–6.
N2 (g) + 3 H2 (g) ⇌ 2 NH3 (g)
Calculate the number of molecules of ammonia present at equilibrium in 11 million cubic meters of air at 25 °C and 730 mmHg. Note that the percent nitrogen and hydrogen in the air are 78.1 % and 0.00005 % respectively.
Butanoic acid was reacted with methanol at 323 K. The equilibrium constant of the reaction at this temperature is 9.0.
CH3OH (aq) + CH3CH2CH2CO2H (aq) ⇌ CH3CH2CH2CO2CH3 (aq) + H2O (aq)
Calculate the number of moles of methyl butanoate present in equilibrium with 4.0 mol of water, 2.0 mol of methanol, and 2.0 mol of butanoic acid at 323 K.
Hydrogen chloride gas can be rapidly formed by directly combining hydrogen gas and chlorine gas above 250 °C. If the Kc for the reaction is 121, and a mixture of H2, Cl2, and HCl at equilibrium contains 1.54×10-3 M H2 and 1.54×10-3 M Cl2, determine the concentration of HCl.
H2 (g) + Cl2 (g) ⇌ 2 HCl (g)
Liquid dinitrogen tetroxide is an oxidizing substance that consists of a mixture of colorless N2O4 and red-brown NO2. If the value of Kc for the equilibrium of the two gases is 0.212 at 100 °C, will a gas be in a much greater concentration than the other at equilibrium? Calculate the equilibrium concentration of NO2 if the equilibrium concentration of N2O4 in a reaction mixture is 2.00×10-3 M.
N2O4 (g) ⇌ 2 NO2 (g)
The reaction P ⇌ Q represents the interconversion of P molecules (orange) and Q molecules (purple). The diagrams below depict four separate experiments showing the progress of the reaction with time:
Calculate the value Kc for the reaction P ⇌ Q.
At 27.0 °C, the aqueous reaction between CH3OH and HBr is as follows: CH3OH(aq) + HBr(aq) → CH3Br(aq) + H2O(l). What is the rate constant for the reverse reaction (kr) if the rate constant for the forward reaction (kf) and equilibrium constant (Kc) at 27.0 °C are, respectively, 1.67×10—4 M—1•s—1 and 1.20×102?
At 63.5 °C, ethanol (CH3CH2OH) has a vapor pressure of 0.526 atm. Determine the Kp and Kc values for the equilibrium CH3CH2OH(l) ⇌ CH3CH2OH(g) at 63.5 °C.
The equilibrium constant (Kp) for the oxidation of nitric oxide (NO) is 1152 at 150 °C.2 NO(g) + O2(g) ⇌ 2 NO2(g)In the reaction mixture at equilibrium, O2 has a partial pressure of 0.345 atm while the partial pressure of NO2 is 0.225 atm. Calculate the partial pressure of NO at equilibrium.
The equilibrium constant (Kc) of the reaction MgC2O4(s) ⇌ Mg2+(aq) + C2O42–(aq) at 25.0°C is 8.6×10–5. In a saturated solution of MgC2O4, calculate the equilibrium concentrations of Mg2+ and C2O42–.
Sulfur dioxide (SO2) gas reacts with oxygen (O2) to produce sulfur trioxide (SO3): 2 SO2(g) + O2(g) ⇌ 2 SO3(g). A 5.5 L reaction vessel is charged with a mixture of SO2 and O2 at 300 °C. When the equilibrium was established, the mixture had the three gases at these partial pressures: PSO2 = 1.15 atm, PO2 = 2.35 atm, and PSO3 = 0.855 atm. Determine Kp.
The diagram below shows nitric oxide (NO) reacting with oxygen (O2) to form nitrogen dioxide (NO2).2 NO(g) + O2(g) ⇌ 2 NO2(g)Using the information in the diagram, calculate the value of the equilibrium constant, Kc, for the reaction. Assume the volume of the container is 3.4 L.
In an equilibrium mixture, [SO2] = 3.50 M and [SO3] = 9.20 M. Calculate [O2] at equilibrium for the mixture.
2 SO2(g) + O2(g) ⇌ 2 SO3(g), Keq = 560
At 30 ºC, the reaction A(g) + 2 B(g) ⇌ 2 C(g) was found to have equilibrium concentrations of [A] = 0.83 M, [B] = 1.12 M, and [C] = 2.25 M. Calculate Kc for the reaction.
The following reaction takes place at very high temperatures:
ZnO(s) + CO(g) ⇌ Zn(l) + CO2(g) Keq = 1.25
If the equilibrium concentration of carbon dioxide (CO2) is found to be 0.213 M, what concentration of carbon monoxide (CO) is present in the reaction mixture?
The formation of hydrogen chloride (HCl) through a reaction of hydrogen (H2) and chlorine (Cl2) is a reversible reaction that takes place according to the following equation:
H2(g) + Cl2(g) ⇌ 2HCl(g)
When the reaction is carried out at 450 °C, the equilibrium mixture contains the following amounts: [H2] = 1.22 M, [Cl2] = 1.35 M and [HCl] = 0.67 M.
Calculate the value of the equilibrium constant (Kc) for this reaction.
The following equation below shows the reaction of hydrogen sulfate anion (HSO4-) with ammonia (NH3) to form sulfate (SO42-) and ammonium ions (NH4+).
HSO4-(aq) + NH3(aq) ⇌ SO42-(aq) + NH4+(aq)
The value of Ka for hydrogen sulfate anion (HSO4-) is 1.26 x 10-2 while the Kb value for ammonia (NH3) is 1.8 x 10-5.
Determine whether the value of Kc will be >1 or <1 for this reaction? Identify the direction which will be favored at equilibrium for this reaction.
2NO(g) + Br2(g) ⇌ 2NOBr(g)
At 600 K, the partial pressures of the three gases in the equilibrium mixture, NO, Br2, and NOBr, are 0.150 atm, 0.115 atm, and 0.348 atm, respectively.
Determine the value of Kc at this temperature.
Write the expression for the equilibrium constant, Kp, and provide the equation that relates Kp to Kc for the reaction C2H6(g) + Cl2(g) ⇌ C2H5Cl(s) + HCl(g).
Cyclobutane gas decomposes to butene gas when heated.
The equilibrium constant Kc for this reaction is 3.0×104 at 700 K. What is the value of Kp at 700 K?
A hypothetical gas phase reaction C → D has a forward rate constant of 4.22×10−2 s−1. The reverse reaction D → C has a rate constant of 1.74×10−4 s−1. Which component, C or D, has a smaller partial pressure at equilibrium?
When the reaction CH4(g) + H2O(g) ⇌ CO(g) + 3 H2(g) occurs at 1200 K, the Kp = 2.47×103. Calculate the Kc for the reaction at this temperature.
The value of Kc for the following reaction 2 NO2(g) ⇌ N2O4(g) is 4.72 at 100°C. Determine its Kp value at this temperature.
Consider the following diagram of a gas-phase reaction wherein each molecule represents 1.0 mol and a box with a volume of 1.0 L. What is the change in the number of gas molecules (Δn) as a result of the reaction?
The reaction PH3BCl3(s) ⇌ PH3(g) + BCl3(g) has Kc = 6.96 × 10–5 at 60 ºC. Determine the value of Kp.
The reaction 2 NO(g) + Br2(g) ⇌ 2 NOBr(g) has Kp = 2.40 at 100 ºC. Determine the value of Kc.
What is the change in the number of gas moles (Δn) for each of the following reactions?
I) H2(g) + Br2(l) → 2HBr(g)
II) (NH4)2CO3(s) → 2NH3(g) + CO2(g) + H2O(g)
III) 3H2(g) + N2(g) → 2NH3(g)
IV) Mg(s) + I2(s) → MgI2(s)
At 789 K, the equilibria for the following reactions are
CuS(s) + H2(g) → Cu(s) + H2S(g) Kc = 78.9
CS2(g) + H2(g) → CS(g) + H2S(g) Kc = 0.289
Based on the given equilibria, what will be the Kc for CuS (s) + CS (g) → Cu (s) + CS2 (g)?
Calculate the equilibrium constant Kp for the following reaction at 373.15 K:
2 NO2(g) ⇌ N2(g) + 2 O2(g)
Use the following reactions and their Kc at the same temperature:
NO(g) + 1/2 O2(g) ⇌ NO2(g) Kc = 8.0×104
2 NO(g) ⇌ N2(g) + O2(g) Kc = 5.0×1024
The dissociation of hydrogen selenide (H2Se) takes place in two steps:
H2Se ⇌ H+ + HSe- K1 = 1.29×10-4
HSe- ⇌ H+ + Se2- K2 = 1.00×10-11Calculate the equilibrium constant for the following reaction:Se2- + 2H+ ⇌ H2Se