CHM102 MasteringChemistry Ch. 15
A mixture initially contains A, B, and C in the following concentrations: [A] = 0.500 M, [B] = 0.700 M, and [C] = 0.500 M. The following reaction occurs and equilibrium is established: A + 2B ⇌ C At equilibrium, [A]= 0.300 M and [C]= 0.700 M. Calculate the value of the equilibrium constant, Kc.
25.9
Given the two reactions: H2S ⇌ HS− + H+ K1 = 9.44 × 10^−8 and HS− ⇌ S2− + H+ K2 = 1.50 × 10^−19 what is the equilibrium constant Kfinal for the following reaction? S2− + 2H+ ⇌ H2S
7.06 x 10^25
A mixture of 0.10 mol of NO, 0.050 mol of H2, and 0.10 mol of H2O is placed in a 1.0-L vessel at 300 K. The following equilibrium is established: 2NO(g) + 2H2(g) ⇌ N2(g) + 2H2O(g) At equilibrium [NO]=0.062M. A) Calculate the equilibrium concentration of H2. B) Calculate the equilibrium concentration of N2. C) Calculate the equilibrium concentration of H2O. D) Calculate Kc.
A) 1.2 x 10^-2 M B) 1.9 x 10^-2 M C) 0.138 M D) 650
What is the proper form of the equilibrium constant expression for the equation? N2(g) + O2(g) ⇌ 2NO(g)
K = [NO]^2 / [N2][O2]
List the equilibria from largest to smallest equilibrium constant.
KCl2 > KBr2 > KI2
Now consider the reaction A + 2B ⇌ C for which in the initial mixture Qc= [C] / [A][B]^2 = 387 Is the reaction at equilibrium? If not, in which direction will it proceed to reach equilibrium?
The reaction will proceed in reverse to form reactants.
Consider the following system at equilibrium: 3A(aq) + 3B(aq) ⇌ 5C(aq) Classify each of the following actions by whether it causes a leftward shift, a rightward shift, or no shift in the direction of the net reaction.
leftward shift -increase [C] -decrease [A] -decrease [B] -double both [B] and [C] rightward shift -increase [A] -increase [B] -decrease [C] no shift -double [A] and reduce [B] to one half
The following system is at equilibrium: X(s) + 3Y(g) ⇌ Z(g) Classify each of the following actions by whether it causes a leftward shift, a rightward shift, or no shift in the direction of the net reaction.
leftward shift -increase the volume rightward shift -decrease the volume no shift -add more X -remove some X
The K of the reaction: NO2(g) + NO3(g) ⇌ N2O5(g) is K = 2.1 × 10^−20. A) What can be said about this reaction? B) Where does the equilibrium of this reaction lie?
A) At equilibrium the concentration of reactants is much greater than that of products. B) to the left
How does the magnitude of Kp for the reaction 2HI(g) ⇋ H2(g) + I2(g) change if the equilibrium is written 6HI(g) ⇋ 3H2(g) + 3I2(g)?
It is cubed.
Consider the equilibrium between NO2 and N2O4. How can you tell if you are at equilibrium?
The color in the tube stops changing.
For the reaction 2HBr(g) ⇌ H2(g) + Br2(g) K = 2.00 × 10^−19 at 298 K what can be said about this reaction at this temperature?
The equilibrium lies far to the left.
For the reaction H2(g) + I2(g) ⇌ 2HI(g) K= 57.0 at 700 K what can be said about this reaction at this temperature?
The reaction contains significant amounts of products and reactants at equilibrium.
The reaction 2CH4(g) ⇌ C2H2(g) + 3H2(g) has an equilibrium constant of K= 0.154. If 6.90 mol of CH4, 4.75 mol of C2H2, and 10.55 mol of H2 are added to a reaction vessel with a volume of 5.00 L , what net reaction will occur?
The reaction will proceed to the left to establish equilibrium.
Given the two reactions PbCl2 ⇌ Pb2+ + 2Cl− K3 = 1.72 × 10^−10 and AgCl ⇌ Ag+ + Cl− K4 = 1.29 × 10^−4, what is the equilibrium constant Kfinal for the following reaction? PbCl2 + 2Ag+ ⇌ 2AgCl + Pb2+
1.03 x 10^-2
Gaseous hydrogen iodide is placed in a closed container at 425 degrees C, where it partially decomposes to hydrogen and iodine: 2HI(g) ⇌ H2(g) + I2(g). At equilibrium it is found that [HI] = 3.58 × 10^−3 M, [H2] = 4.86 × 10^−4 M , and [I2]= 4.86 × 10^−4 M . What is the value of Kc at this temperature?
1.84 × 10^−2
The reaction A2(g) + B(g) ⇌ A(g) + AB(g) has an equilibrium constant of Kp=2. The accompanying diagram shows a mixture containing A atoms (red - 2 ), A2 molecules (2) , and AB molecules (red and blue - 4). How many B atoms should be added to the diagram to illustrate an equilibrium mixture?
2 atoms
At 2000 ∘C the equilibrium constant for the reaction 2NO(g) ⇌ N2(g) + O2(g) is Kc = 2.4×10^3. A) If the initial concentration of NO is 0.171 M, what is the equilibrium concentration of NO? B) If the initial concentration of NO is 0.171 M, what is the equilibrium concentration of N2? C) If the initial concentration of NO is 0.171 M, what is the equilibrium concentration of O2?
A) 1.7 x 10^-3 M B) 8.5 x 10^-2 M C) 8.5 x 10^-2 M
A) Write the expression for Kc for the following reaction: 2Ag(s) + Zn2+(aq) ⇌ 2Ag+(aq) + Zn(s) B) Indicate whether the reaction is homogeneous or heterogeneous.
A) Kc = [Ag+]^2 / [Zn2+] B) heterogeneous
A) Write the expression for Kc for the following reaction: Ni(CO)4(g) ⇌ Ni(s) + 4CO(g) B) Indicate whether the reaction is homogeneous or heterogeneous.
A) Kc = [CO]^4 / [Ni(CO)4] B) heterogeneous
A) Write the expression for Kc for the following reaction: CH4(g) + 2H2S(g) ⇌ CS2(g) + 4H2(g) B) Indicate whether the reaction is homogeneous or heterogeneous.
A) Kc = [CS2][H2]^4 / [CH4][H2S]^2 B) homogeneous
A) Write the expression for Kc for the following reaction: HF(aq) ⇌ H+(aq) + F−(aq) B) Indicate whether the reaction is homogeneous or heterogeneous.
A) Kc = [H+][F-] / [HF] B) homogeneous
A) Write the expression for Kc for the following reaction: 3NO(g) ⇌ N2O(g) + NO2(g) B) Indicate whether the reaction is homogeneous or heterogeneous.
A) Kc = [N2O][NO2] / [NO]^3 B) homogeneous
A) Based on the shown energy profile, predict whether kf > kr or kf < kr. B) Using the equation kf/kr = the equilibrium constant, predict whether the equilibrium constant for the process is greater than 1 or less than 1.
A) kf > kr B) greater than 1
Methanol (CH3OH) can be made by the reaction of CO with H2: CO(g) + 2H2(g) ⇌ CH3OH(g) A) The enthalpy change for the reaction is -90.7 kJ. To maximize the equilibrium yield of methanol, would you use a high or low temperature? B) To maximize the equilibrium yield of methanol, would you use a high or low pressure?
A) low temperature B) high pressure
The equilibrium constant for the reaction: 2NO(g) + Br2(g) ⇌ 2NOBr(g) is Kc=1.3×10−2 at 1000 K A) At this temperature does the equilibrium favor NO and Br2, or does it favor NOBr? B) Calculate Kc for 2NOBr(g) ⇌ 2NO(g) + Br2(g) C) Calculate Kc for NOBr(g) ⇌ NO(g) + 1/2Br2(g)
A) the equilibrium favor NO and Br2 B) 77 C) 8.8
Hydrogen is used as a rocket fuel because it is very light and reacts explosively and completely with oxygen. For the combustion reaction 2H2(g) + O2(g) ⇌ 2H2O(g) what is the likely magnitude of the equilibrium constant K?
K > 10^3
Ammonia can be produced via the chemical reaction N2(g) + 3H2(g) ⇌ 2NH3(g) During the production process, the production engineer determines the reaction quotient to be Q= 3.56×10−4. If K= 6.02×10−2, what can be said about the reaction?
The reaction is not at equilibrium and will proceed to the right.
The industrial production of lime (CaO) from calcium carbonate is accomplished via the following reaction: CaCO3(s) ⇌ CaO(s) + CO2(g) Given the following data: Temperature K 298 1.93 x 10^-23 1200 1.01 what can be said about this reaction?
The reaction makes more lime at higher temperatures.
For the following systems at equilibrium A : 2NOCl(g) ⇌ 2NO(g) + Cl2(g) B : H2(g) + I2(g) ⇌ 2HI(g) classify these changes by their effect.
leftward shift - system A decrease container size no shift -system B increase container size -system B decrease container size rightward shift -system A increase container size
For a certain chemical reaction, ΔH degrees = −156 kJ. Assuming the reaction is at equilibrium, classify each of the following actions by whether it causes a leftward shift, a rightward shift, or no shift in the direction of the net reaction.
leftward shift -increase the temperature rightward shift -decrease the temperature no shift N/A
For the following systems at equilibrium A: CaCO3(s) ⇌ CaO(s) + CO2(g)g ΔH = +178 kJ/mol B : PCl3(g) + Cl2(g) ⇌ PCl5(g) ΔH = -88 kJ/mol classify these changes by their effect.
leftward shift -system C decrease temperature -system D increase temperature no shift N/A rightward shift -system C increase temperature -system D decrease temperature
