Question 1

The esterification of acetic acid and ethanol is given by the reaction below: C₂H₅OH(aq)+ CH₃COOH(aq)⇌ CH₃COOC₂H₅(aq)+ H₂O(l) When 1.00 mol of ethanol was mixed with 2.00 mol of acid in a 1.00 L flask,0.86 mol of ester was formed at room temperature.What is the value of the equilibrium constant,K_c?

Accepted Answer

The balanced chemical equation for the reaction is:
CH3CH2OH + CH3COOH ⇌ CH3COOCH2CH3 + H2O

The equilibrium constant expression is given by:
Kc = ([CH3COOCH2CH3] / [CH3CH2OH] [CH3COOH])

At equilibrium, the concentration of ethanol is (1 - 0.86) = 0.14 mol/L, the concentration of acetic acid is (2 - 0.86) = 1.14 mol/L, and the concentration of ester is 0.86 mol/L.

Substituting the values into the equilibrium constant expression, we get:
Kc = (0.86 / (0.14 x 1.14))
Kc = 5.351

Therefore, the value of the equilibrium constant is 5.4 (rounded to one significant figure).

The correct answer is D.

Question 2

At a certain temperature,bromine and nitric oxide react to form nitrosyl bromide: Br₂(g)+ 2 NO(g)⇌ 2 NOBr(g). When initial amounts of Br₂,NO,and NOBr are mixed,the concentration of NOBr increases.Which statement below is true?

Accepted Answer

If the concentration of NOBr increases, the reaction is shifting towards the products side. Therefore, the reaction quotient (Q) is less than the equilibrium constant (Kc) at that temperature, so K_c > Q.

Question 3

For the isomerization reaction: Butane ⇌ isobutane K_p equals 25 at 500°C.If the initial pressures of butane and isobutane are 10.atm and 0.0 atm,respectively,what are the pressures of the two gases at equilibrium?

Accepted Answer

From the given equilibrium constant and initial pressures, we can set up an ICE table:

Butane ⇌ isobutane 
I: 10 atm      0.0 atm 
C: -x           +x 
E: 10-x         x

Using the equilibrium constant expression: 
Kc = [isobutane] / [butane] 
25 = x / (10-x) 
25(10-x) = x 
250 - 25x = x 
26x = 250 
x = 9.62

Therefore, the equilibrium pressures are: 
P(butane) = 10 - x = 0.38 atm 
P(isobutane) = x = 9.62 atm

So, the correct answer is option A.

Question 4

An equilibrium mixture of CO,O₂ and CO₂ at a certain temperature contains 0.0010 M CO₂ and 0.0015 M O₂.At this temperature,K_c,equals 1.4 × 10² for the reaction: 2 CO(g)+ O₂(g)⇌ 2 CO₂(g). What is the equilibrium concentration of CO?

Accepted Answer

We can use the equilibrium constant expression to set up an ICE table: 2 CO(g) + O₂(g) ⇌ 2 CO₂(g) I: 0.0010 0.0015 0 C: -2x -x 2x E: 0.0010 - 2x 0.0015 - x 0.0010 + 2x where x is the change in concentration. The equilibrium constant expression is: Kc = [CO₂]2 / ([CO]2[O₂]) Substituting the equilibrium concentrations and the given Kc value: 1.4 × 10² = (0.0010 + 2x)2 / ((0.0015 - x)(0.0010 - 2x)2) Solving for x gives: x = 2.2 × 10^-3 Substituting x back into the equilibrium concentrations: [CO] = 0.0010 - 2x = 2.6 × 10^-3, which is closest to choice B.

Question 5

The equilibrium constant,K_p,equals 3.40 for the isomerization reaction: Cis-2-butene ⇌ trans-2-butene. If a flask initially contains 0.250 atm of cis-2-butene and 0.125 atm of trans-2-butene,what is the equilibrium pressure of each gas?

Accepted Answer

The answer of The equilibrium constant,K_p,equals 3.40 for the isomerization...

Question 6

For the reaction: 4 HCl(g)+ O₂(g)⇌ 2 Cl₂(g)+ 2 H₂O(l),the equilibrium constant is 0.063 at 400 K.If the reaction quotient is 0.100,which of the following statements is not correct?

Accepted Answer

The reaction quotient (Q) is greater than the equilibrium constant (K), indicating that the reaction will shift to the left to reach equilibrium. This means that the concentrations of the reactants (HCl and O2) will increase, and the concentrations of the products (Cl2 and H2O) will decrease. Therefore, statement D is not correct.

Question 7

When baking soda is heated it decomposes according to the following reaction: 2 NaHCO₃(s)⇌ Na₂CO₃(s)+ H₂O(g)+ CO₂(g) If sufficient baking soda is placed in a container and heated to 90°C,the total pressure of the gases is 0.5451 atm.What is the value of K_p at that temperature?

Accepted Answer

The answer of When baking soda is heated it decomposes...

Question 8

The equilibrium constant is equal to 5.00 at 1300 K for the reaction: 2 SO₂(g)+ O₂(g)⇌ 2 SO₃(g). If initial concentrations are [SO₂] = 1.20 M,[O₂] = 0.45 M,and [SO₃] = 1.80 M,the system is

Accepted Answer

The answer of The equilibrium constant is equal to 5.00...

Question 9

At a certain temperature the equilibrium constant,K_c,equals 0.11 for the reaction: 2 ICl(g)⇌ I₂(g)+ Cl₂(g). What is the equilibrium concentration of ICl if 0.75 mol of I₂ and 0.75 mol of Cl₂ are initially mixed in a 2.0-L flask?

Accepted Answer

We can set up a table to track the changes in concentration as the reaction reaches equilibrium: | | ICl | I₂ | Cl₂ | |---------|-------|---------------|---------------| | Initial | x | 0.75 | 0.75 | | Change | -2x | +x | +x | | Equil. | 0.11x | 0.75 + x | 0.75 + x | At equilibrium, we know that the equilibrium constant, K, equals 0.11. Therefore: K = [I₂]^2[Cl₂]/[ICl]^2 0.11 = (0.75 + x)^2/x^2 Solving for x gives x = 0.45 M. Therefore, the equilibrium concentration of ICl is 0.11x = 0.045 M, which is answer choice C.

Question 10

At a certain temperature,K_c equals 1.4 × 10² for the reaction: 2 CO(g)+ O₂(g)⇌ 2 CO₂(g). If a 2.50-L flask contains 0.400 mol of CO₂ and 0.100 mol of O₂ at equilibrium,how many moles of CO are also present in the flask?

Accepted Answer

From the given reaction, we can write the expression for equilibrium constant as: K = [CO₂]^2 / ([CO]^2[O₂]) Substituting the given values of K and concentrations at equilibrium, we get: 1.4 × 10² = (0.400 mol/L)^2 / ([CO]^2 (0.100 mol/L)) Solving for [CO], we get: [CO] = 0.169 mol/L As the volume of the flask is given as 2.50 L, we can calculate the total number of moles of CO present as: moles of CO = [CO] x volume of flask = 0.169 mol/L x 2.50 L = 0.422 mol Therefore, the answer is B) 0.169 mol.

Question 11

For the reaction,A(g)+ 2 B(g)⇌ 2 C(g),K_c = 1 × 10^-10 at 25°C.Which of the following statements is true?

Accepted Answer

The value of the equilibrium constant (Kc) is less than 1, which indicates that the concentration of products is smaller than the concentration of reactants at equilibrium. Therefore, statement B is false.

The reaction produces two moles of product for every mole of reactant consumed, thus Δn = (2-1-1) = 0. Therefore, statement A is false.

Since Kc is very small, it can be assumed that the reverse reaction is favored over the forward reaction. Therefore, statement C is true.

The value of Kp can only differ from Kc if the reaction involves gases and the number of moles of gas changes during the reaction. However, in this case, the number of moles of gas does not change, so Kp and Kc will have the same value. Therefore, statement D is false.

Question 12

The following two isomers of C₃H₇NO exist in equilibrium with each other in solution: If K_c = 0.57 at 25°C and the initial concentration of the reactant is 0.50 M and the product is 0.70 M,what are the concentrations at equilibrium?

Accepted Answer

The answer of The following two isomers of C₃H₇NO exist...

Question 13

The equilibrium constant,K_p,equals 3.40 at 25°C for the isomerization reaction: Cis-2-butene ⇌ trans-2-butene. If a flask initially contains 1.00 atm of each gas,in what direction will the system shift to reach equilibrium?

Accepted Answer

The equilibrium constant, K_p, is greater than 1, which indicates that the forward reaction (cis-2-butene → trans-2-butene) is favored at equilibrium. Therefore, the system will shift towards the right in order to reach equilibrium, resulting in an increase in the concentration of trans-2-butene and a decrease in the concentration of cis-2-butene. Hence, the correct answer is B.

Question 14

Given the hypothetical reaction: 2 A(s)+ x B(g)⇌ 3 C(g),K_p = 0.0105 and K_c = 0.45 at 250°C.What is the value of the coefficient x?

Accepted Answer

The answer of Given the hypothetical reaction: 2 A(s)+ x...

Question 15

Cyclohexane (C₆H₁₂)undergoes a molecular rearrangement in the presence of AlCl₃ to form methylcyclopentane (MCP)according to the equation: C₆H₁₂ ⇌ MCP If K_c = 0.143 at 25°C for this reaction,predict the direction the reaction will shift if the initial concentrations of C₆H₁₂ and MCP are 0.200 M and 0.100 M,respectively.The system

Accepted Answer

According to Le Chatelier's principle, the reaction will shift in the direction that relieves the stress caused by the change in concentration. In this case, the initial concentration of MCP is higher than the equilibrium concentration, indicating that the forward reaction is favored. To counteract this, the reaction will shift to the left, reducing the amount of MCP and increasing the amount of C₆H₁₂. Therefore, the answer is A, the system will shift left.

Question 16

K_p is equal to 48.70 at 731 K for the reaction: H₂(g)+ I₂(g)⇌ 2 HI(g).Initially the mixture contains 0.08592 atm each of H₂ and I₂ and 1.0000 atm of HI.What is the pressure of HI at equilibrium?

Accepted Answer

The answer of K_p is equal to 48.70 at 731...

Question 17

Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures according to the reaction: PCl₅(g)⇌ PCl₃(g)+ Cl₂(g) At 250°C,0.250 M PCl₅ is added to a flask.If K_c = 1.80,what are the equilibrium concentrations of each gas?

Accepted Answer

First, we need to set up an ICE table to determine the equilibrium concentrations:
PCl5: 0.250 M - x
PCl3: x
Cl2: x

Next, we can plug these values into the equilibrium expression and solve for x:
1.80 = (x)(x)/(0.250-x)

Solving for x gives x = 0.222 M.

Therefore, the equilibrium concentrations are:
[PCl5] = 0.250 - 0.222 = 0.0280 M
[PCl3] = [Cl2] = 0.222 M

So the answer is A.

Question 18

At a certain temperature,bromine and nitric oxide react to form nitrosyl bromide: Br₂(g)+ 2 NO(g)⇌ 2 NOBr(g). When 0.010 mol Br₂ is mixed with 0.025 mol NO and 0.015 mol NOBr in a 2.50 L flask,the concentration of NOBr decreases.Which statement below is true?

Accepted Answer

The answer of At a certain temperature,bromine and nitric oxide...

Question 19

Which statement is true for a reaction with K_c equal to 2.43 × 10^-12?

Accepted Answer

A very small Kc value indicates that the reaction hardly proceeds towards completion, favoring the reactants significantly.

Question 20

Cyclohexane (C₆H₁₂)undergoes a molecular rearrangement in the presence of AlCl₃ to form methylcyclopentane (CH₃C₅H₉)according to the equation: C₆H₁₂ ⇌ CH₃C₅H₉ If K_c = 0.143 at 25°C for this reaction,find the equilibrium concentrations of C₆H₁₂ and CH₃C₅H₉ if the initial concentrations are 0.200 M and 0.100 M,respectively.

Accepted Answer

The answer of Cyclohexane (C₆H₁₂)undergoes a molecular rearrangement in the...

Quiz 13: Chemical Equilibrium

At a certain temperature,bromine and nitric oxide react to form nitrosyl bromide: Br₂(g) + 2 NO(g) ⇌ 2 NOBr(g) . When initial amounts of Br₂,NO,and NOBr are mixed,the concentration of NOBr increases.Which statement below is true?

For the isomerization reaction: Butane ⇌ isobutane K_p equals 25 at 500°C.If the initial pressures of butane and isobutane are 10.atm and 0.0 atm,respectively,what are the pressures of the two gases at equilibrium?

An equilibrium mixture of CO,O₂ and CO₂ at a certain temperature contains 0.0010 M CO₂ and 0.0015 M O₂.At this temperature,K_c,equals 1.4 × 10² for the reaction: 2 CO(g) + O₂(g) ⇌ 2 CO₂(g) . What is the equilibrium concentration of CO?

The equilibrium constant,K_p,equals 3.40 for the isomerization reaction: Cis-2-butene ⇌ trans-2-butene. If a flask initially contains 0.250 atm of cis-2-butene and 0.125 atm of trans-2-butene,what is the equilibrium pressure of each gas?

For the reaction: 4 HCl(g) + O₂(g) ⇌ 2 Cl₂(g) + 2 H₂O(l) ,the equilibrium constant is 0.063 at 400 K.If the reaction quotient is 0.100,which of the following statements is not correct?

When baking soda is heated it decomposes according to the following reaction: 2 NaHCO₃(s) ⇌ Na₂CO₃(s) + H₂O(g) + CO₂(g) If sufficient baking soda is placed in a container and heated to 90°C,the total pressure of the gases is 0.5451 atm.What is the value of K_p at that temperature?

The equilibrium constant is equal to 5.00 at 1300 K for the reaction: 2 SO₂(g) + O₂(g) ⇌ 2 SO₃(g) . If initial concentrations are [SO₂] = 1.20 M,[O₂] = 0.45 M,and [SO₃] = 1.80 M,the system is

At a certain temperature the equilibrium constant,K_c,equals 0.11 for the reaction: 2 ICl(g) ⇌ I₂(g) + Cl₂(g) . What is the equilibrium concentration of ICl if 0.75 mol of I₂ and 0.75 mol of Cl₂ are initially mixed in a 2.0-L flask?

At a certain temperature,K_c equals 1.4 × 10² for the reaction: 2 CO(g) + O₂(g) ⇌ 2 CO₂(g) . If a 2.50-L flask contains 0.400 mol of CO₂ and 0.100 mol of O₂ at equilibrium,how many moles of CO are also present in the flask?

For the reaction,A(g) + 2 B(g) ⇌ 2 C(g) ,K_c = 1 × 10^-10 at 25°C.Which of the following statements is true?

The following two isomers of C₃H₇NO exist in equilibrium with each other in solution: If K_c = 0.57 at 25°C and the initial concentration of the reactant is 0.50 M and the product is 0.70 M,what are the concentrations at equilibrium?

The equilibrium constant,K_p,equals 3.40 at 25°C for the isomerization reaction: Cis-2-butene ⇌ trans-2-butene. If a flask initially contains 1.00 atm of each gas,in what direction will the system shift to reach equilibrium?

Given the hypothetical reaction: 2 A(s) + x B(g) ⇌ 3 C(g) ,K_p = 0.0105 and K_c = 0.45 at 250°C.What is the value of the coefficient x?

K_p is equal to 48.70 at 731 K for the reaction: H₂(g) + I₂(g) ⇌ 2 HI(g) .Initially the mixture contains 0.08592 atm each of H₂ and I₂ and 1.0000 atm of HI.What is the pressure of HI at equilibrium?

Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures according to the reaction: PCl₅(g) ⇌ PCl₃(g) + Cl₂(g) At 250°C,0.250 M PCl₅ is added to a flask.If K_c = 1.80,what are the equilibrium concentrations of each gas?

At a certain temperature,bromine and nitric oxide react to form nitrosyl bromide: Br₂(g) + 2 NO(g) ⇌ 2 NOBr(g) . When 0.010 mol Br₂ is mixed with 0.025 mol NO and 0.015 mol NOBr in a 2.50 L flask,the concentration of NOBr decreases.Which statement below is true?

Which statement is true for a reaction with K_c equal to 2.43 × 10^-12?

Quiz 13: Chemical Equilibrium

At a certain temperature,bromine and nitric oxide react to form nitrosyl bromide: Br2(g) + 2 NO(g) ⇌ 2 NOBr(g) . When initial amounts of Br2,NO,and NOBr are mixed,the concentration of NOBr increases.Which statement below is true?

For the isomerization reaction: Butane ⇌ isobutane Kp equals 25 at 500°C.If the initial pressures of butane and isobutane are 10.atm and 0.0 atm,respectively,what are the pressures of the two gases at equilibrium?

An equilibrium mixture of CO,O2 and CO2 at a certain temperature contains 0.0010 M CO2 and 0.0015 M O2.At this temperature,Kc,equals 1.4 × 102 for the reaction: 2 CO(g) + O2(g) ⇌ 2 CO2(g) . What is the equilibrium concentration of CO?

The equilibrium constant,Kp,equals 3.40 for the isomerization reaction: Cis-2-butene ⇌ trans-2-butene. If a flask initially contains 0.250 atm of cis-2-butene and 0.125 atm of trans-2-butene,what is the equilibrium pressure of each gas?

For the reaction: 4 HCl(g) + O2(g) ⇌ 2 Cl2(g) + 2 H2O(l) ,the equilibrium constant is 0.063 at 400 K.If the reaction quotient is 0.100,which of the following statements is not correct?

When baking soda is heated it decomposes according to the following reaction: 2 NaHCO3(s) ⇌ Na2CO3(s) + H2O(g) + CO2(g) If sufficient baking soda is placed in a container and heated to 90°C,the total pressure of the gases is 0.5451 atm.What is the value of Kp at that temperature?

The equilibrium constant is equal to 5.00 at 1300 K for the reaction: 2 SO2(g) + O2(g) ⇌ 2 SO3(g) . If initial concentrations are [SO2] = 1.20 M,[O2] = 0.45 M,and [SO3] = 1.80 M,the system is

At a certain temperature the equilibrium constant,Kc,equals 0.11 for the reaction: 2 ICl(g) ⇌ I2(g) + Cl2(g) . What is the equilibrium concentration of ICl if 0.75 mol of I2 and 0.75 mol of Cl2 are initially mixed in a 2.0-L flask?

At a certain temperature,Kc equals 1.4 × 102 for the reaction: 2 CO(g) + O2(g) ⇌ 2 CO2(g) . If a 2.50-L flask contains 0.400 mol of CO2 and 0.100 mol of O2 at equilibrium,how many moles of CO are also present in the flask?

For the reaction,A(g) + 2 B(g) ⇌ 2 C(g) ,Kc = 1 × 10-10 at 25°C.Which of the following statements is true?

The following two isomers of C3H7NO exist in equilibrium with each other in solution: If Kc = 0.57 at 25°C and the initial concentration of the reactant is 0.50 M and the product is 0.70 M,what are the concentrations at equilibrium?

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 1.00 atm of each gas,in what direction will the system shift to reach equilibrium?

Given the hypothetical reaction: 2 A(s) + x B(g) ⇌ 3 C(g) ,Kp = 0.0105 and Kc = 0.45 at 250°C.What is the value of the coefficient x?

Kp is equal to 48.70 at 731 K for the reaction: H2(g) + I2(g) ⇌ 2 HI(g) .Initially the mixture contains 0.08592 atm each of H2 and I2 and 1.0000 atm of HI.What is the pressure of HI at equilibrium?

Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures according to the reaction: PCl5(g) ⇌ PCl3(g) + Cl2(g) At 250°C,0.250 M PCl5 is added to a flask.If Kc = 1.80,what are the equilibrium concentrations of each gas?

At a certain temperature,bromine and nitric oxide react to form nitrosyl bromide: Br2(g) + 2 NO(g) ⇌ 2 NOBr(g) . When 0.010 mol Br2 is mixed with 0.025 mol NO and 0.015 mol NOBr in a 2.50 L flask,the concentration of NOBr decreases.Which statement below is true?

Which statement is true for a reaction with Kc equal to 2.43 × 10-12?

At a certain temperature,bromine and nitric oxide react to form nitrosyl bromide: Br₂(g) + 2 NO(g) ⇌ 2 NOBr(g) . When initial amounts of Br₂,NO,and NOBr are mixed,the concentration of NOBr increases.Which statement below is true?

For the isomerization reaction: Butane ⇌ isobutane K_p equals 25 at 500°C.If the initial pressures of butane and isobutane are 10.atm and 0.0 atm,respectively,what are the pressures of the two gases at equilibrium?

An equilibrium mixture of CO,O₂ and CO₂ at a certain temperature contains 0.0010 M CO₂ and 0.0015 M O₂.At this temperature,K_c,equals 1.4 × 10² for the reaction: 2 CO(g) + O₂(g) ⇌ 2 CO₂(g) . What is the equilibrium concentration of CO?

The equilibrium constant,K_p,equals 3.40 for the isomerization reaction: Cis-2-butene ⇌ trans-2-butene. If a flask initially contains 0.250 atm of cis-2-butene and 0.125 atm of trans-2-butene,what is the equilibrium pressure of each gas?

For the reaction: 4 HCl(g) + O₂(g) ⇌ 2 Cl₂(g) + 2 H₂O(l) ,the equilibrium constant is 0.063 at 400 K.If the reaction quotient is 0.100,which of the following statements is not correct?

When baking soda is heated it decomposes according to the following reaction: 2 NaHCO₃(s) ⇌ Na₂CO₃(s) + H₂O(g) + CO₂(g) If sufficient baking soda is placed in a container and heated to 90°C,the total pressure of the gases is 0.5451 atm.What is the value of K_p at that temperature?

The equilibrium constant is equal to 5.00 at 1300 K for the reaction: 2 SO₂(g) + O₂(g) ⇌ 2 SO₃(g) . If initial concentrations are [SO₂] = 1.20 M,[O₂] = 0.45 M,and [SO₃] = 1.80 M,the system is

At a certain temperature the equilibrium constant,K_c,equals 0.11 for the reaction: 2 ICl(g) ⇌ I₂(g) + Cl₂(g) . What is the equilibrium concentration of ICl if 0.75 mol of I₂ and 0.75 mol of Cl₂ are initially mixed in a 2.0-L flask?

At a certain temperature,K_c equals 1.4 × 10² for the reaction: 2 CO(g) + O₂(g) ⇌ 2 CO₂(g) . If a 2.50-L flask contains 0.400 mol of CO₂ and 0.100 mol of O₂ at equilibrium,how many moles of CO are also present in the flask?

For the reaction,A(g) + 2 B(g) ⇌ 2 C(g) ,K_c = 1 × 10^-10 at 25°C.Which of the following statements is true?

The following two isomers of C₃H₇NO exist in equilibrium with each other in solution: If K_c = 0.57 at 25°C and the initial concentration of the reactant is 0.50 M and the product is 0.70 M,what are the concentrations at equilibrium?

The equilibrium constant,K_p,equals 3.40 at 25°C for the isomerization reaction: Cis-2-butene ⇌ trans-2-butene. If a flask initially contains 1.00 atm of each gas,in what direction will the system shift to reach equilibrium?

Given the hypothetical reaction: 2 A(s) + x B(g) ⇌ 3 C(g) ,K_p = 0.0105 and K_c = 0.45 at 250°C.What is the value of the coefficient x?

K_p is equal to 48.70 at 731 K for the reaction: H₂(g) + I₂(g) ⇌ 2 HI(g) .Initially the mixture contains 0.08592 atm each of H₂ and I₂ and 1.0000 atm of HI.What is the pressure of HI at equilibrium?

Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures according to the reaction: PCl₅(g) ⇌ PCl₃(g) + Cl₂(g) At 250°C,0.250 M PCl₅ is added to a flask.If K_c = 1.80,what are the equilibrium concentrations of each gas?

At a certain temperature,bromine and nitric oxide react to form nitrosyl bromide: Br₂(g) + 2 NO(g) ⇌ 2 NOBr(g) . When 0.010 mol Br₂ is mixed with 0.025 mol NO and 0.015 mol NOBr in a 2.50 L flask,the concentration of NOBr decreases.Which statement below is true?

Which statement is true for a reaction with K_c equal to 2.43 × 10^-12?