Mastering Chem Ch. 14

The equilibrium-constant of the reaction NO2(g)+NO3(g)⇌N2O5(g) is K=2.1×10−20. What can be said about this reaction?

At equilibrium the concentration of reactants is much greater than that of products.

According to Le Chatelier's principle, if the volume of the vessel containing the equilibrium system shown below is decreased, there will be an increase in the concentration of ________ and a decrease in the concentration of ________. H2(g)⇌2H(g)

H2(2 is down subscript), H

The equilibrium constant, Kp, equals 3.40 at 25°C for the isomerization reaction: cis-2-butene → trans-2-butene. If a flask initially contains 3.00 atm of each gas, in what direction will the system shift to reach equilibrium?

It will shift right.

The acid HOCl (hypochlorous acid) is produced by bubbling chlorine gas through a suspension of solid mercury(II) oxide particles in liquid water according to the equation 2HgO(s)+H2O(l)+2Cl2(g)⇌2HOCl(aq)+HgO⋅HgCl2(s) What is the equilibrium-constant expression for this reaction?

K=[HOCl]^2/[Cl2]^2

Identify the proper form of the equilibrium-constant expression for the equation N2(g)+O2(g)⇌2NO(g)

K=[NO]^2/[N2][O2]

At a certain temperature, hydrogen and iodine react to form hydrogen iodide: H2(g) + I2(g) → 2 HI(g). When initial amounts of H2, I2, and HI are mixed, the concentration of HI increases. Which statement below is true?

Kc > Q

A mixture initially contains A, B, and C in the following concentrations: [A] = 0.500 M , [B] = 1.35 M , and [C] = 0.500 M . The following reaction occurs and equilibrium is established: A+2B⇌C At equilibrium, [A] = 0.370 M and [C] = 0.630 M . Calculate the value of the equilibrium constant, Kc.

Kc= 1.43 0.500...1.35....0.500 [A]=0.500-x=0.370 x=0.130M [B]=1.35-2(0.130)=1.09M [C]=0.500+0.130=0.63M Kc=0.63/0.370(1.09)^2=1.43

Determine the value of the equilibrium constant, Kgoal, for the reaction CO2(g)⇌C(s)+O2(g), Kgoal=? by making use of the following information: 1. 2CO2(g)+2H2O(l)⇌CH3COOH(l)+2O2(g), K1 = 5.40×10−16 2. 2H2(g)+O2(g)⇌2H2O(l), K2 = 1.06×1010 3. CH3COOH(l)⇌2C(s)+2H2(g)+O2(g), K3 = 2.68×10−9

Kgoal= 1.24x10^-7

Determine the equilibrium constant, Kgoal, for the reaction 4PCl5(g)⇌P4(s)+10Cl2(g), Kgoal=? by making use of the following information: P4(s)+6Cl2(g)⇌4PCl3(g), K1=2.00×1019 PCl5(g)⇌PCl3(g)+Cl2(g), K2=1.13×10−2

Kgoal=8.15x10^-28

Consider the following system at equilibrium: D(aq)+E(aq)⇌2F(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 [F],Triple both [E] and [F],Decrease [D],Decrease [E] Rightward shift: Increase [D],Increase [E],Decrease [F] No shift: Triple [D] and reduce [E] to one third

For a certain chemical reaction, ΔH∘=−156kJ. 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

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: Remove some X,Add more X

Calculate the equilibrium concentration of [N2] if the initial concentrations are 2.27 M N2 and 0.55 M O2. (This N2/O2 concentration ratio is the ratio found in air.)

N2=2.25 M (rounded)

The decomposition of nitrosyl bromide is exothermic: 2 NOBr(g)⇌2 NO(g)+Br2(g). Which of the following changes in reaction condition will shift the reaction to the left?

None of these

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.

Where does the equilibrium of this reaction lie?

To the left

For those mixtures that are not at equilibrium, will the reaction go in the forward or reverse direction to reach equilibrium?

(2) and (3) will go in the forward direction

Carbonyl fluoride, COF2, is an important intermediate used in the production of fluorine-containing compounds. For instance, it is used to make the refrigerant carbon tetrafluoride, CF4 via the reaction 2COF2(g)⇌CO2(g)+CF4(g), Kc=6.40 If only COF2 is present initially at a concentration of 2.00 M, what concentration of COF2 remains at equilibrium?

0.33 M

Consider the reaction CO(g)+NH3(g)⇌HCONH2(g), Kc=0.710 If a reaction vessel initially contains only CO and NH3 at concentrations of 1.00 M and 2.00 M, respectively, what will the concentration of HCONH2 be at equilibrium?

0.513 M

Calculate the equilibrium concentration of [O2].

0.53 M (rounded)

What is the equilibrium constant, K c, for the reaction: 2Hg(l)+O2(g)⇌2HgO(s) if the amounts of reactants and products at equilibrium are: 1.00 g of HgO(s), 2.00 mL of Hg(l), and 1.60 M O2(g)? (The molar mass and density of HgO(s) is 217 g/mol, and 1.10 g/cm3. The molar mass and density of Hg(l) is 201 g/mol, and 13.6 g/mL.)

0.625

Calculate the equilibrium partial pressures of ClF3, ClF, and F2 if only ClF3 is present initially, at a partial pressure of 1.39 atm .

1.01 (rounded from 1.013), 0.377, 0.377

A 1.50 L vessel contains an equilibrium mixture of 0.100 mol of NO, 0.150 mol of Br2, and 0.250 mol of NOBr at 25°C. What is the value of K p for the reaction below? 2NO(g)+Br2(g)⇌2NOBr(g)

2.56 by the formula PV = nRT find the pressure for the NO P (1.5 L) = 0.100 mol (0.08206 L-atm/mol-K)(298K) P = 1.63 atm NO @ 0.150 times as many moles of Br2 .... = 2.445 atm Br2 @ 0.250 times as many moles of NOBr ....= 4.075 atm NOBr Kp = [NOBr]^2 / [NO]^2 [BR2] Kp = [4.075]^2 / [1.63]^2 [2.445] Kp = 2.556

Calculate the equilibrium concentration of [NO].

4.5*10^-2 M

For the reaction shown below, <N2O4(g)⇌2NO2(g)>, N2O4 and NO2 have equilibrium concentrations, [N2O4]eq = 2.160 × 10-4 and [NO2]eq = 1.001 × 10-3, respectively. The equilibrium constant, Kc, for this reaction equals ________.

4.64×10^−3

For the reaction: N2(g) + 2 O2(g) → 2 NO2(g), Kc = 8.3 × 10-10 at 25°C. What is the concentration of N2 gas at equilibrium when the concentration of NO2 is twice the concentration of O2 gas?

4.8 × 10^9 M

The decomposition of ammonia is: 2 NH3(g) = N2(g) + 3 H2(g). If Kp is 1.5 × 103 at 400°C, what is the partial pressure of ammonia at equilibrium when N2 is 0.20 atm and H2 is 0.15 atm?

6.7 × 10^-4 atm

Which will alter the composition of an equilibrium mixture?

all of the above

If additional SCN- is added to the equilibrium system shown below, Le Chatelier's principle predicts a net reaction from ________ to ________, causing the red color to become ________. Fe3+(aq)+SCN−(aq)⇌FeSCN2+(aq) yellowcolorless red

left,right,darker

Which reaction mixture is at equilibrium?

mixture (1)

Kc = 1.2 × 10-42 at 500 K for the reaction shown below. H2(g)⇌2H(g) If H2 = 1 × 10-2 M and H = 1.2 × 10-22 M, in order to achieve equilibrium a net reaction must occur from ________ to ________ until Qc = ________.

right,left,Kc (make sure c is down subscript)