Equilibrium Questions and Answers

Sodium bicarbonate gives solutions that are slightly alkaline (approximately pH 8.3), and similar solutions of sodium hydroxide (lye) are very basic with a pH around 12 or more. Lye will cause major damage, if not death, if swallowed, while sodium bicarbonate is a common antacid.

Salicylic acid reacts with acetic acid to form aspirin, acetyl salicylic acid. A 0.353 molar solution of salicylic acid in water has a pH of 1.70. Calculate the Ka and pKa of salicylic acid in water.

Hydrofluoric acid, HF, unlike hydrochloric acid, is a weak electrolyte. What is the pH of a 0.078 M aqueous solution of HF? The K₂ for HF is 6.8x10-4. You must solve the quadric equation for this problem. Express your answer to two decimal places.

An analytical chemist is titrating 73.6 mL of a 0.8900 M solution of hydrazoic acid (HN3) with a 0.7000 M solution of KOH. The pK, of hydrazoic acid is 4.72. calculate the pH of the acid solution after the chemist has added 104. mL of the KOH solution to it. Note for advanced students: you may assume the final volume equals the initial volume of the solution plus the volume of KOH solution added. Round your answer to 2 decimal places.

When colorless solutions containing Fe³+ (aq) ions and SCN- (aq) ions are combined, a deep-red complex ion, FeSCN2+ (aq) quickly forms, as shown in the net ionic equation above. Which of the following explains the observation that adding a few additional crystals of KSCN(s) results in the red color of the solution becoming deeper? The added KSCN (s) dissolves, disturbing the charge balance in the solution, causing Fe(SCN), to precipitate as a red solid. A B Ⓒ Fe (aq) + SCN- (aq) FeSCN²+ (aq) Colorless Colorless Red D The added KSCN(s) dissolves, causing the solution to become saturated in SCN ions, which appear red at high concentrations. The added KSCN(s) dissolves, causing the reaction system to respond by producing more product to partially consume SCN- (aq) and reduce its concentration. The added KSCN(s) dissolves, causing the reaction system to respond by forming more Fe³+ ions, which have a deep orange color at high concentrations.

At night, an equilibrium reaction between two different nitrogen compounds generates N₂O5 in the atmosphere, as represented below. Reaction 1: NO3(g) + NO₂(g) N₂O5 (9) K = 2.6 x 10-11 During the day, solar radiation is absorbed by NO3 (9), resulting in its decomposition. Which of the following best explains whether the equilibrium concentration of N₂O5 (g) in the atmosphere in the daytime is different from that in the nighttime, and why? [N₂O5] will be higher during the day, because the decomposition of NO3(g) results in an increase in the rate of production of N₂O5 (g). B C D [N₂O5] will be higher during the day, because NO₂(g) will be in excess, leading to an increase in the rate of production of N₂O5 (9). [N₂O5] will be higher at night, because the decomposition of NO3(g) in the daytime will result in an increase in the rate of consumption of N₂O5 (9) to reform NO₂(g). N₂O5] will be about the same at nighttime and daytime, because the amount of NO₂(g) will not be changed and the equilibrium will not be affected.

Hydroxylamine, HONH2, like ammonia, is a Brønsted base. A 0.15 M solution has a pH of 10.11. Calculate the K, of hydroxylamine? Calculate the pK, of hydroxylamine? What is the percentage ionization of HONH₂?

CO₂ (g) C(s) + O2(g) Keq = 1 x 10-32 at 1000 K The formation of Fe (s) and O₂(g) from FeO (s) is not thermodynamically favorable at room temperature. In an effort to make the process favorable, C (s) is added to the FeO (s) at elevated temperatures. Base on the information above, which of the following gives the value of Keq and the sign of AG for the reaction represented by the equation below at 1000 K? 2 FeO (s) + C(s) 2 Fe(s) + CO₂ (g)

CaF2(s) Ca²+ (aq) + 2F (aq) K =4.0 × 10 1 The concentration of F (aq) in drinking water that is considered to be ideal for promoting dental health is 4.0 x 105 M. Based on the information above, the maximum concentration of Ca2+ (aq) that can be present in drinking water without lowering the concentration of F (aq) below the ideal level is closest to

"Acid rain" forms when rain falls through air polluted by oxides of sulfur and nitrogen, which dissolve to form acids such as H₂SO3, H₂SO4, and HNO3. Trees and plants are affected if the acid rain has a pH of 3.5 or lower. What is the hydrogen ion concentration in acid rain that has a pH of 3.40? What is the pH of a solution having twice your calculated hydrogen ion concentration?

Which of the following is the correct expression for the concentration based equilibrium constant for the reaction: Mg(OH)₂ (s) Mg2+ (aq) + 2 OH (aq) A) see problem image B) see problem image C) see problem image D) see problem image

Using the information in the table, the rate law for the reaction 2 A(g) + B(g) → C(g) + D(g) is

A group of students working in a chemistry lab are planning a procedure to neutralize hydrochloric acid (HCI, strong acid). How should they BEST accomplish this? Titrate a weak base into the strong acid. Titrate a weak acid into the strong acid. Titrate a strong base into the strong acid. Titrate a strong acid into the strong acid.

Which of the following is true of electrolytes? Strong electrolytes dissociate completely into ions. Strong electrolytes dissociate partially into ions. Strong electrolytes do not conduct electricity. Weak electrolytes dissociate completely into ions.

Suppose a 500. mL flask is filled with 1.3 mol of CO, 0.30 mol of NO and 1.8 mol of CO2. The following reaction becomes possible: NO₂(g)+CO(g) ⇒NO(g) + CO₂(g) The equilibrium constant K for this reaction is 7.24 at the temperature of the flask. Calculate the equilibrium molarity of NO. Round your answer to two decimal places.

250.0 mL of 0.300 M HCl is added to 250.0 mL of 0.300 M NaOH in a coffee cup calorimeter. Type numbers in the boxes. The neutralization reaction that occurs is: HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l) Before the solutions are mixed they are both at 24.52°C. After mixing the solutions the temperature increases until it remains constant at 26.58°C. Assuming no heat lost to the surroundings, how much heat was given off by this reaction (in joules)? (Assume the specific heats and densities of the solutions are the same as water, 1.00 g/mL)

Suppose a 250. mL flask is filled with 2.0 mol of CH4, 1.6 mol of CO and 0.30 mol of H₂. This reaction becomes possible: CH₂(g) + H₂O(g) CO(g) + 3H₂(g) Complete the table below, so that it lists the initial molarity of each compound, the change in molarity of each compound due to the reaction, and the equilibrium molarity of each compound after the reaction has come to equilibrium. Use x to stand for the unknown change in the molarity of CH4. You can leave out the M symbol for molarity.

F- ion can react with BF3, forming the BF4- anion. In this reaction, the BF3 molecule acts as a Lewis acid, accepting an electron pair from the F-ion to form a coordinate covalent bond. the F-ion acts as a Brønsted base, accepting a proton from the BF3 molecule. the F-ion acts as a Lewis base, donating a proton to the BF3 molecule the F-ion acts as a Brønsted acid, donating a proton to the BF3 molecule. the BF3 molecule acts as a Lewis base, donating an electron pair to the F-ion to form a coordinate covalent bond.

2 NO(g) +2H₂(g) → N₂(g)+2H₂O(g) At the temperature the engineer picks, the equilibrium constant K, for this reaction is 0.84. The engineer charges ("fills") four reaction vessels with nitrogen monoxide and hydrogen, and lets the reaction begin. She then measures the composition of the mixture inside each vessel from time to time. Her first set of measurements are shown in the table below. Predict the changes in the compositions the engineer should expect next time she measures the compositions.

To 1.0 L of a 0.36 M solution of HCIO₂ is added 0.20 mol of NaCIO Calculate the [HCIO₂] at equilibrium Express your answer using two significant figures.

A tiny sample of an aqueous solution of two substances R and P is sketched below, as if it was under an imaginary microscope so powerful that individual molecules could be seen. (The water molecules are not shown.) R and P can interconvert. That is, R can turn into P, and P can turn back into R: R(aq)=P(aq) number of R molecules: The equilibrium constant K for this equilibrium is 9. Predict the number of R and P molecules in this sample when the interconversion reaches equilibrium. number of P molecules:

Consider the following system at equilibrium at 698 K: 2 HI (g) H₂ (g) + I₂ (9) When some H₂ (g) is added to the equilibrium system at constant temperature: The reaction must: The concentration of I2 will: A. Run in the forward direction to reestablish equilibrium. B. Run in the reverse direction to reestablish equilibrium. C. Remain the same. It is already at equilibrium. A. Increase. B. Decrease. C. Remain the same.

Calculate the percent dissociation of 4-chlorobutanoic acid (C3H6CICO2H) in a 3.6M aqueous solution of the stuff. You may find some useful data in the ALEKS Data resource. Round your answer to 2 significant digits.

On a journey deep into the Klingon empire, the Starship Enterprise runs out of dilithium crystals, and is forced to use hydrazine, N₂H4, as a backup fuel. Passing N₂H over a catalyst causes it to decompose according to: 3 N₂H₁ (1) → 4 NH3(g) + N₂(g) What total volume of gases at 783 °C and 25.3 atm are produced by the reaction of 4.8×10° g N₂H₂?

Consider the reaction 2 SO₂(g) + O₂(g) 2 SO3(g) The equilibrium constant of the above reaction is Kp. If only SO3 gas is present initially, the partial pressure of SO3 at equilibrium is given by [Assume that Pso3 <<Ptotal at equilibrium and Ptotal = P]

Predict the equilibrium concentration of O, in the reaction described below by constructing an equilibrium expression for Qc, constructing an ICE table, writing an equilibrium expression for Kc, and solving for the equilibrium concentration. Complete Parts 1-4 before submitting your answer. N₂(g) + O₂(g) 2 NO(g) In a 1.0 L container at high temperature, 0.20 mol N, and 0.15 mol O, are allowed to react. Set up the expression for Qc. Each reaction participant must be represented by one tile. Do not combine terms. Once the expression is constructed, solve for Qc to determine the direction of the reaction.

In the following situation it is necessary to perform a material shift. What are the new initial concentrations? Note: It is not necessary to solve the ICE problem in this case. [A] initial = 0.0 M [B] initial = 0.5 M [C] initial = 0.5M [A] initial = 0.0 M [B] initial = 0.75 M [C] initial = 0.75M [A] initial = 0.25 M [B] initial = 0.5 M [C] initial = 0.5M [A] initial = 0.0 M [B] initial = 0.0 M [C] initial = 1.0M

Calculate either [H3O+] or [OH-] for each of the solutions at 25 °C. Solution A: [OH-] = 2.79 x 10-7 M; [H₂O+] = Solution B: [H3O+] = 8.43 x 10-⁹ M; [OH-] = Solution C: [H3O+] = 6.83 x 10-4 M; [OH¯] = Which of these solutions are basic at 25 °C? Solution A: [OH-] = 2.79 × 10-7 M Solution B: [H₂O+] = 8.43 × 10-⁹ M Solution C: [H3O+] = 6.83 × 10-4 M

After Procedure Step 3, the solution in Well A1 was in equilibrium. What happened to the solution in Well A1 during Procedure Step 5? Did the equilibrium shift? Explain this on the basis of the Le Chatelier Principle?

For the following reaction at equilibrium in a reaction vessel, which one of these changes would cause the NOI concentration to increase? 2NOI(g) = 2NO(g) + 12(g), ΔHrxn = 45.3 kJ/mol (Select all that applies) A) add a catalyst B) decrease the temperature C) increase the volume D) compress the gas mixture into a smaller volume E) decrease the partial pressure of NO F) increase the temperature G) increase the partial pressure of NO H) add more NO

The molar solubility of PbCl2 is 5.08 . 10-3 M. Calculate the Ksp for PbCl₂.

0.1 mol of HCI is added to water so that pH become 2. Calculate the volume of solution (in L), if there is no change in volume during mixing.

Enter complete ionic equation to show the reaction of aqueous Hg2(NO3)2 with aqueous sodium bromide to form solid Hg2Br2 and aqueous sodium nitrate. Express your answer as a chemical equation. Identify all of the phases in your answer.

Calculate the pH of a solution of 0.22 M C₂H5NH₂ solution. The K for C₂H5NH₂ is 5.6 x 104. Hints: 1st Is C₂H5NH₂ a weak acid or a weak base? 2nd Write a balanced equation for when C₂H5NH₂ reacts with water. 3rd - Use K, and an ICE box to solve for things. 4th Calculate the pOH. 5th Calculate the pH.

Consider the reaction below. The reaction quotient for a specific moment is 1.44 10³. If the equilibrium constant is 8.51 10³, what needs to happen in order for the reaction to reach equilibria? Select all that apply. 3A+1B 2C There will be a net gain in reactant. There will be a net gain in product. The forward reaction will procede more than the reverse reaction. The reverse reaction will occur more than the forward reaction. The system will shift to the left. The system will shift to the right.

Calculate the pH and pOH of 226 mL of a phosphate buffer that is composed of 0.353 M HPO and 0.188 is 4.50 x 10-13. M PO at 25°C. The Ka of HPO Report your answer to 3 sig figs.

The half-equivalence point of a titration occurs half way to the equivalence point, where half of the analyte has reacted to form its conjugate, and the other half still remains unreacted. If 0.580 moles of a monoprotic weak acid (K₂ = 7.5 x 10-5) is titrated with NaOH, what is the pH of the solution at the half-equivalence point?

A 1.00 L solution contains 0.344 M HA (Ka = 6.40.10-4) and 0.572 M NaA. What is the pH of this solution? What is the pH if 0.188 L of 0.122 M KOH is added to the solution be? What is the pH if 0.376 L of 0.122 M KOH is added to the solution be?

Ammonia ionizes as follows in water: NH3 + H₂O NH4+ + OH- The Kb for this reaction is 1.8 x 10-5. Calculate the [OH] if the [NH3] is 0.5M originally. The ammonia is a weak base. Weak base equilibria is done very much like weak acids except the equation and equilibrium constant expression contains [OH] instead of [H*], and the constant is Ka instead of Kb. The rest of the process is the same.

An unknown student takes an unknown mass of an unknown weak acid, dissolves it in an unknown amount. I of water, and titrates it with a strong base of unknown concentration. When the student has added 8.36 mL of base (initial buret V=0.00 mL), using a pH meter the student measures the pH of the solution and finds it to be 2.08. The student continues the titration until the equivalence point is reached for removal of one proton. At this time the students buret reads 34.88 ml. Determine the dissociation constant, Ka, of the acid? [Must show your work or reasoning!!]

What can accurately be said about equilibrium? Select all that apply to all equilibrium situations. The concentrations of the reactants and products are constant over time. The rate of the reverse reaction is essentially 0. It is microscopically dynamic, but macroscopically static. The rate of the forward reaction exceeds that of the reverse reaction. The rate of the forward reaction is essentially zero. The concentration of the reactants and products are equal to one another. It is macroscopically dynamic, but microscopically static. The rates of the forward and reverse reaction are equal.

The complex ion Cu(NH3)42+ is formed in a solution made of 0.0300 M Cu(NO3)2 and 0.300 M NH3. What are the concentrations of Cu²+, NH3, and Cu(NH3)42+ at equilibrium? The formation constant*, Kf, of Cu(NH3)4²+ is 1.70 × 10¹³.

If all sulphur present in 2 mmol of FeS2 is converted into SO2 and finally into H₂SO3, how many ml of a given concentration of NaOH is required to completely neutralize the H₂SO3? 20 mL of 0.4 M solution 24 mL of 1/3M solution 20 mL of 0.1 M solution 11 mL of 0.2 M solution

At what pH of the solution precipitation of NiS can be prevented by passing 0.1 M H₂S gas through a 0.1 M Ni²+ solution? Given: Ksp of NiS = 10-17 H₂S 2H+ + S²; K= 10-21 pH = 1 pH = 2 pH = 3 pH = 4

When N₂O5 is heated, it dissociates as N₂O5 = N₂O3 + O₂, Kc = 4.5. At the same time, N₂O3 also decomposes as N₂O3 = N₂O + O₂. If initially 4 mole of N₂O5 are taken in a 1 Lt. flask and allowed to attain equilibrium, concentration of O₂ was found to be 4.5M. Which of the following is/are correct? Equilibrium concentration of N₂O is 5/3 Equilibrium concentration of N₂O3 is 7/6 equilibrium constant of the reaction N2O3 = N₂O + O₂ is approximately 6.428 All are correct

Consider two solutions, solution A: 1.0 M hydrofluoric acid (HF) and solution B: a mixture of 1.0 M HF and 1.0 M NaF. If a strong base is added to both of these solutions, what will the result be? Both will have a decrease in pH. Solution A will increase in pH and Solution B's pH won't change very much. Solution A will decrease in pH and Solution B will increase. Both will have an increase in pH. Solution A will increase in pH and Solution B will decrease.

Bromine monochloride is synthesized using the reaction Br₂(g) + Cl₂(g) = 2 BrCl(g) Kp = 1.1 x 10-4 at 150 K A 203.0 L flask initially contains 0.965 kg of Br₂ and 1.083 kg of Cl₂. Calculate the mass of BrCl, in grams, that is present in the reaction mixture at equilibrium. Assume ideal gas behavior. What is the percent yield of BrCl?

At a given temperature, the elementary reaction AB, in the forward direction, is first order in A with a rate constant of 0.0320 s-1. The reverse reaction is first order in B and the rate constant is 0.0590 s-1. What is the value of the equilibrium constant for the reaction AB at this temperature? What is the value of the equilibrium constant for the reaction BA at this temperature?

A sealed 0.5 L flask is charged with 0.500 mol of 12 and 0.500 mol of Br2. An equilibrium reaction ensues: I2 (g) + Br2 (g) 2IBr (g) When the container contents achieve equilibrium, the flask contains 0.84 mol of IBr. The value of Keq is 21 6.1 11

What is the actual concentration of molecular NH3 in a 0.200 M solution of ammonia? The Kb value for ammonia is 1.80 x 105. 0.200 M 0.198 M 1.80 x 10-5M 3.6 × 10-M 1.90 x 10-³M