Equilibrium Questions and Answers

A mixture of 0 100 mol CO2 0 0500 mol H2 and 0 100 mol H2O are place in a 1 00 L flask and allowed to come to equilibrium as shown below At equilibrium CO2 0 0954 M CO2 g H2 g CO g H2O g a What are the equilibrium concentrations of H2 CO and H2O

Hydrogen gas reacts with oxygen gas to produce water as shown below 2H2 O2 2H O Approximately how many grams of hydrogen gas are needed to completely react with 128 grams of oxygen gas 31 68 g H2 8 08 g H2 O 16 16 g H2 30 68 g H

In the atmosphere the concentration of N is 0 033 M and the concentration of O is 0 00810 M at 25 C Suppose the concentration of NO g in the atmosphere is 1 13 10 7 M at 25 C What is the equilibrium constant for this reaction at 25 C Type the correct answer in the box Express your answer to two significant figures Keq x 10 31

The image shows a small volume within a 1 0 L solution with a solute concentration of 1 M The blue spheres represent the solute particles in the solution Identify whether you would need to add more solute or more solvent to the solution to achieve each of the following solutions Each image represents the same small volume within the solution Add solute Add solvent

Solubility g in 100g water 100 80 60 40 20 0 10 20 30 40 50 Temperature C 60 70 B A 80 D Creative Commons license Wikipedia https commons wikimedia org wiki File Solubility curve jpg In 400 g of water at 50 degrees Celsius approximately what mass of substance C will

If the pOH of a solution is 3 3 then the pH is Select solution is Select and the

A student adds a small amount of phenolphthalein to an erlenmeyer flask and it changes to pink when he adds the base sodium hydroxide What is phenolphthalein considered to be O an indicator O a titrant an analyte O a quotient

3 Two reactions have similar AHrn values AH xn 1 AH xn 2 but reaction 1 has a much smaller standard entropy change than reaction 2 AS rxn 1 AS rxn 2 At 298 K which statements about these two reactions must be correct I II Reaction 1 must have a larger equilibrium constant Keq 1 Keq 2 Reaction 1 must have a larger Arrhenius prefactor A1 A 2 A I only C Both I and II B II only D Neither I nor II

he hydrogen ion concentration of a basic solution is 8 80 x 10 11 M What is the pH of the solution

2 Label each property as either Acid Base or Salt a pH of 7 14 b Feel slippery e HCI i Used in cleaning agents f Taste sour j Proton donor c pH of 7 g MgCl k Taste bitter d NaOH h pH less than 7 1 Proton acceptor

5 In a titration a 25 0 mL sample of 0 150 M HCl is neutralized with 44 45 mL of Ba OH 2 a Write the balanced molecular equation for this reaction b What is the molarity of the base solution

Which of the following best models a weak acid in aqueous solution Water molecules are not included

f the pOH of a solution is 3 3 then the pH is Select Select and the solutio

Before the bottle is squeezed the system is at equilibrium After the bottle has been squeezed the system eventually returns to equilibrium Is the concentration of CO the same in both equilibrium situations before and after squeezing the bottle What about the equilibrium constant

3 A researcher is trying to conduct an experiment that requires a solution with a high concentration of hydronium ions There are several solutions in the stock room they can choose from which includes two bottles of hydrochloric acid and two bottles of acetic acid with varying molarities Hydrochloric acid is a strong acid and acetic acid is a weak acid Which of the following solutions would have the highest concentration of hydronium ion H30 A B C D 1 0 10 3 M HCI 1 0 10 3 M HC H302 0 050 M HCI 0 050 M HC H3O2 4 An aqueous solution of sodium hydroxide reacts completely with a solution of hydrochloric acid After all the water evaporates from the reaction mixture what will remain A Sodium chloride B Chlorohydroxide C Sodium oxide D Sodium chlorate

Use the Intarmation graph End table to answer the following question During a lab investigation students created two colorless solutions by adding different amounts of sodium nitrite to 100 g water at 80 C as shown in the table One of the solutions is saturated and the other is unsaturated The students did not label the solutions They plan to cool both solutions to 60 C to help them determine which solution is saturated Solubility of Sodium Nitrite 5 001 5 Amigos Temperature C Solution Amount of 1 2 sodium nitrite 135 g 95 q Will the students be successful O A No because a precipitate will not form in either solution at the lower temperature OB Yes because a precipitate will only form in one of the solutions at the lower temperature indicating it is the saturated solution OC Yes because a precipitate will only form in one of the solutions at the lower temperature indicating it is the unsaturated solution OD No because a precipitate will form in both solutions at the lower temperature

12 What does pH measure A Electron concentration B Neutron concentration C Hydroxide ion concentration D Hydrogen ion concentration

1 Stronger acids are those that A hold on to their protons more strongly B lose their protons more easily C more completely inhibit polarity in water D exhibit hydrogen bonding 2 For two acids of equal concentration the stronger acid has a higher concentration of hydroxide ions a higher pH a higher concentration of hydronium ions A B C D a stronger bond

14 8 pts 35 mL of KOH are diluted to a volume of 1 0L It takes 27 45 mL of 0 2815 M HBr to neutralize a 25 00 mL sample of DILUTED KOH solution What is the concentration of the ORIGINAL UNDILUTED KOH solution

No Work No Credit M V M V 1 What volume of 4 50 M nitric acid stock solution is needed to make 3 5 L of a 1 60 M solution 2 I have 345mL of a 1 5M NaCl solution If I boil the water until the volume of the solution is 250 ml what will the molarity of the solution be 3 What volume of 3 25 M stock solution to make 4 0 L of a 1 50 M sulfuric acid solution 4 What volume of 5 00 M stock solution of lead II nitrate in milliliters is needed to make 250 mL with concentration of 1 75 M 5 What volume of 4 00 M Na OH solution is needed to make 2 50 L of a 1 50M solution 6 What volume of 0 050M HCI solution can be made by dilution 250 mL of a 10 M HCI

24 What is the OH when there is a concentration of H of 00987 M 1 x 10 14 log H x OH

5 In the equilibrium reaction 2NO g O g 2NO g 114 6 kJ What will be the change in the equilibrium concentration of NO under each of the following conditions a O is added Forward b energy is added c NO is removed d a catalyst is added e it is placed in an ice bath f the volume is increased g O is removed h NO is added

1 In the equilibrium reaction 4HCl g O g 2H O g 2Cl g 114 4 kJ Predict the direction of equilibrium shift if the following changes occur a oxygen is added b HCl is removed c H O is added d Cl is removed 2 In the equilibrium reaction 2HI g H g L g Predict the direction of equilibrium shift if the following changes occur a HI is added b HI is removed c H is added d I is added 3 In the equilibrium reaction 4HCl g O g 2H O g 2Cl g 114 4 kJ Predict the direction of equilibrium shift if the following changes occur a the pressure in increased b energy is added c volume of the system is increased d it is placed in an ice bath 4 Methanol can be manufactured using the following equilibrium reaction CO g 2H g CH OH g energy Predict the direction of equilibrium shift if the following changes occur a a decrease in temperature b an increase in pressure c addition of H g d addition of a catalyst

What type of particle is present in solutions with a pH of 5 O Hydrogen Atoms O Hydrogen lons O Hydroxide lons O Silicon Molecules OOH Particles O None of these

Explain why a titration with an acid and a base requires a pH indicator

Label each of the following as an acid base conjugate acid or conjugate base Each reaction will only have one of each B HC H O H O H3O C H O F H O HF OH

41 2 points In the reaction below what are the coefficients of the products in the balanced equation Ga NO 3 Ca 2 and 2 1 and 2 1 and 3 2 and 3

What is the pH of a solution with a pOH of 3 9

7 Determine the equilibrium constant given the following information N O4 g 2 NO g at equilibrium NO 0 035 M N 04 0 149 M 8 Determine the missing concentration at equilibrium given the following information 2 NH3 g N g 3 H g K 19231 At equilibrium N 2M and H 9M Find NH3 9 If K 1 18 x 102 at 40 for the following reaction 2 NO g N2O4 g And at equilibrium NO 0 055 M find N 04 10 For the following information 2 NO g N 04 g K 4 66 x 103 at 25 At equilibrium N 04 0 257 M Find NO TQDIM

3 Write equilibrium constant expressions for the following 2 H g O g 2 H O 1 4 Determine the equilibrium constant given the following information PC13 g Cl g PCls g At equilibrium PC13 0 029 M Cl 0 067 M PC1s 0 034 M 5 For the equation NH4Cl s NH3 g HCl g If NH3 0 035 M HC 0 255 M and there is 4 18 g of NH4Cl at equilibrium what is the equilibrium constant 6 Find the equilibrium constant for the reaction COC1 g CO g Cl g if at equilibrium COC1 0 324 M CO 2 69 x 10 M Cl 4 12 x 106 M

4 Sample Problem Use the following experimental concentrations to determine the K for the reaction N 3 H 2 NH3 N 0 921 M H 0 763 M and NHJ 0 157 M Sk

2 NO g Cl2 g 2 NOCI g If the pressure of the system were decreased then the equilibrium position would Tap to Select Answer The result is that the amount of NO would Tap to Select Answer and the amount of NOCI would

b Calculate the equilibrium constant for the reaction written instead as 2HCl g H g Cl 9 Show all necessary work no work no credit If necessary do the problem on a separate sheet of paper and insert a photo of it in the designated space c What is the relationship of the K values in parts a and b I

For the following questions consider the following equation 2Mg s O2 g 2MgO s How many moles of magnesium are needed to react with 16 0 g of O O 0 500 mol o 1 00 mol O 2 00 mol O 3 00 mol 4 00 mol

A solution whose OH 2 0 x 10 7 would be O neutral acidic O basic

Express the rate of the reaction in terms of the rate of concentration change for each of the three species involved 2 NO O 2 NO rate of reaction rate of reaction rate of reaction

Calculate the pH of a 0 M solution of HCI Enter only your pH do not indicate units

Cycle Initial Volumes 1 2 3 4 5 6 7 8 9 ANALYSIS Volume Beaker A mL 650 550 450 400 350 350 300 300 250 250 Volume Beaker B mL 0 100 200 250 300 300 350 350 400 400 Cycle 10 11 12 13 14 15 16 17 18 19 1 If we measure reaction rates in mL cycle what was the rate of the forward reaction water going from beaker A B once the system was at equilibrium i e when the volumes remained Volume Beaker A mL 250 200 200 200 200 200 200 200 200 200 Volume Beaker B mL 400 400 450 450 450 450 450 450 450 450

Which is a true statement A substance that donates a proton is a base Some substances can act as both an acid and a base A substance that acts as an acid cannot also act as a base Water is neutral and cannot act as an acid or a base

Which statement is incorrect All Br nsted Lowry acids are Arrhenius acids All Br nsted Lowry bases are Arrhenius bases All Arrhenius acids are Br nsted Lowry acids All Arrhenius bases are Br nsted Lowry bases

A strong acid lonizes almost completely in water Is alway highly concentrated Has a low K value

7 What is the pH when 0 0628 g of HCl is dissolved in 0 500 L of water

1 In a 0 2000M solution of a monoprotic weak acid HA H 9 86 X 104 M What is the dissociation constant K of this acid The equilibrium constant of H and of the corresponding anion are both equal to 9 86 X 104 M What is the equilibrium concentration of the acid HA to four significant figures Type your answer here M The equilibrium value of HA is the initial value minus the equilibrium value of H The formula for the dissociation constant is K H X A HA Substitute the known values and calculate Give your answer in scientific notation and to three significant digits Ka Type your answer here X 10 6

7 A buffer solution contains 1 31 mol Na PHO and 0 509 mol NaHPHO3 Complete parts a e 14 pts a Give the chemical formula for the weak acid in the buffer b Give the chemical formula for the weak base in the buffer c Calculate the pH of buffer solution d Write the balanced chemical equation for the reaction that occurs when a strong acid a source of H is added to the buffer e A small amount of strong acid a source of H is added to the buffer solution How will this affect the pH of the buffer solution Circle your predictions below the pH of the buffer solution will increase the change in the pH of the buffer solution will be decrease small large

7 A buffer solution contains 1 31 mol Na PHO3 and 0 509 mol NaHPHO3 Complete parts a e 14 pts a Give the chemical formula for the weak acid in the buffer b Give the chemical formula for the weak base in the buffer c Calculate the pH of buffer solution d Write the balanced chemical equation for the reaction that occurs when a strong acid a source of H is added to the buffer e A small amount of strong acid a source of H is added to the buffer solution How will this affect the pH of the buffer solution Circle your predictions below the pH of the buffer solution will increase the change in the pH of the buffer solution will be decrease small large

Calculate the POH of 0 15 M solution of CH3COONa aq The K for CH3COOH acetic acid is 1 8x10 5 O a 9 08 O b 4 92 O c 5 04 O d 8 96

In the following reaction how many moles of KCI will be produced 2K Cl 2KCI

base with the chemical formula CsH oNH and a pK of 2 89 Complete parts a e 30 pts a Write the base ionization reaction for CsHioNH and the corresponding equilibrium expression b Calculate the pH of a 1 25 M solution of CsH1ONH c The conjugate acid of CsH10NH is Show your work here and it has Ka d An aqueous solution of CsH 0NH was titrated with an aqueous solution of HCI Write the neutralization reaction that occurs during the titration Which of the following best describes the pH at the equivalence point circle your answer pH 7 00 pH 7 00 pH 7 00 e Which of the following is a better base circle your choice below

2 The researchers measured the decomposition of bupropion at different pH values The data is shown at right Under what pH conditions is the drug most stable and therefore ideally stored at pH In bupropion 1 0000 0 0000 1 0000 2 0000 3 0000 4 0000 5 0000 6 0000 7 0000 0 pH 13 20 40 pH 11 80 60 Time hrs pH 9 100 pH 5 pH 7 120 140

9 Consider the reversible reaction C s CO g 2 CO g Complete parts a e 24 pts a Write the equilibrium expression with reactants and products expressed as partial pressures b The reaction was examined at two different temperatures Once equilibrium was established the equilibrium partial pressures were measured Calculate K for the reaction at each temperature Temp C Pco atm Pco atm Kp 850 1050 0 0623 0 00370 0 9377 0 9963 c Review your nswers in part b and complete the following statements As temperature increased the equilibrium constant increased decreased This means the reaction is endothermic exothermic d Calculate AG ran in kJ mol for the reaction at 850 C Is the reaction spontaneous or nonspontaneous at this temperature e After the experiments in part b another experiment was run at 850 C At some point in the experiment the pressure of CO is 0 00569 atm and the pressure of CO is 0 313 atm Which direction will the reaction proceed in order to achieve equilibrium