Equilibrium Questions and Answers

1 4 2 3 The gas phase reaction 2NO g N O4 g is an exothermic reaction The decomposition of N O4 in equilibrium mixture of NO g and N O4 g can be increased by JEE Main Online 2018 1 Addition of an inert gas at constant volume 2 Increasing the pressure Lowering the temperature 4 Addition of an inert gas at constant pressure

3 Which one of the following is not a reversible reaction a 2HI g H g 12 g b PC15 g PC13 g Cl 2 g c 2KC103 s 2KCl s 302 g d CaCO3 s CaO s CO2 g Tog

In the reaction A 3B2C initially 10 moles each of A and B were taken If equilibrium pressure is 8 atm and of A 20 then K P will be 1 1 2 118 3 1 16 4 13X 2

m constant equilibrium is established K 6 8 x 10 2 and 1 0 mol of sulphur are heated to 90 C in a 1 0 litre ves what will be the partial pressure of H S at equilibrium The equilibri At 90 C the following H g S s H S g If 0 2 mol of hydrogen

A solution is made by mixing 50 0 g of A molar mass 68 0 g mol and 50 0 g of B molar mass 35 0 g mol At 25 C the vapor pressures of pure A and B are 285 and 132 mmHg respectively Calculate the information requested below Enter your calculated answer below and be sure to upload your work and calculations receive full credit Note Correct answers without supporting work earn 0 points a Mole fraction of A in the solution b Vapor pressure of solution at 25 C in mmHg c Mole fraction of A in vapor above the solution

7 The first disinfectant used by Joseph Lister was called carbolic acid This substance now is known as phenol C6H5OH pKa 10 90 What is the pH of a 0 10 M solution of phenol d 5 95 e 5 45 a 3 50 b 8 55 C 6 50

In this reaction CO2 g CF4 9 2COF2 g what would be the effect if the volume of the system is decreased by increasing the pressure Equilibrium shifts toward the product No shift takes place Equilibrium shifts toward the reactant None are correct

For the reaction HF aq H aq F aq K 7 2 x 104 Calculate the hydrogen ion concentration H for a 0 63 M solution of HF in water Don forget to set up the table first

70 Determine the value of equilibrium constant K for the reaction A g B g 2AB g if 10 moles of A2 15 moles of B2 and 5 moles of AB are placed in a 2 litre vessel and allowed come to equilibrium The final concentration of AB is 7 5 M a 4 5 b 1 5 c 0 6 11 1 1 d None of these

73 180 Mark for Review When initial concentration of a reactant is doubled in a reaction its half life period is not affected The order of the reaction is Zero 02 4 hr m More than zero but less than first First

For each of the salts on the left match the salts on the right that can be compared directly using Ksp values to estimate solubilities If more than one salt on the right can be directly compared include all the relevant salts by writing your answer as a string of characters without punctuation e g ABC 1 calcium chromate 2 manganese II hydroxide Ksp Write the expression for K in terms of the solubility s for each salt when dissolved in water calcium chromate manganese II hydroxide A Ag SO4 B CaSO4 C ZnS D CrPO4 Ksp Note Multiply out any number and put it first in the Ksp expression Combine all exponents for

87 In which of the following equilibrium change in volume of the system does not alter th number of moles a N g O g 2NO g c N g 3H g 2NH3 g b PC15 g PC13 g Cl g d SO Cl g SO g Cl g

82 following eq N 04 8 2NO g Then the select the correct graph which shows the variation in concentrations of N 04 against concentrations of N 04 VC V L b c d N 04 N 04 N 04 N 04

3 Calculate non ionized the ratio of ionized and forms of the drug novocaine in the stomach pH 1 98 and the intestine pH 8 98 if its pK 8 98 Where will the drug be absorbed in the stomach and or intestines 10 01

With calcium hydroxide the reactions Ca OH 2 s Ca2 2OH and Ca2 OH Ca OH have ksp 5 3 x 10 6 and pK1 1 55 respectively A How many moles of calcium hydroxide are dissolved in 125mL of water ksp 5 3 x 10 6

The equilibrium of a pure water dissociating into its ions has a relation time of around 57 microseconds at 25 C Find the rate constants of both the forward and reverse reaction The density of water is 1 00 g mL

21 pH of a strong diprotic acid H A at concentrations i 10 4 M ii 104 N 22 are respectively 3 7 and 4 0 Calcium 1 b 4 and 3 7 c 4 and 4 XOH d 3 7 and 3 KA

71 At 87 C the following equilibrium is established H g S s RO H S g K 7 x 10 If 0 50 mole of hydrogen and 1 0 mole of sulphur are heated to 87 C in 1 0 L vessel what will be the partial pressure of H S at equilibrium a 0 966 atm b 1 38 atm c 0 0327 atm d 1 atm d into an quacuated chamber and comes to equilibrium at 247 C and 2 0 n DOL

A 2 lit flask initially containing one mol of each CO and H O was sealed and heated to 700 k where the following equilibrium was established CO g H O g CO g H g Kc 9 2 Now the flask was connected to another flask containing some pure CO g at same temperature and pressure by means of a narrow tube of negligible volume When the equilibrium was restored moles of CO was found to be double of its moles at first equilbrium Determine volume of CO g flask

6 a For the equilibrium COCl2 g CO g Cl2 g Kp is 8x10 9 at 127 C Calculate the degree of dissociation of phosgene and AH for the reaction at that temperature Given that total pressure is 2 atm and AS 400K 30 cal deg mol 4 CU 2012 1 b WBSU 2015 6 a

Histidine is a common amino acid found in many proteins and other natural sources There are 3 deprotonation steps of this substance with three acid dissociation constants K 2x10 2 K 9 5x10 7 and K3 8 3x10 10 when ionic strength is 0 1 as follows a If the pH of a histidine solution is 6 05 which form of histidine is present in the solution b How many ml of 0 1135M NaOH are needed to get a buffer solution with 70 nl

68 COCl gas dissociates according to the equation COCl g CO g Cl g When heated to 700 K the density of the gas mixture at 1 16 atm and at equilibrium is 1 16 g litre The degree of dissociation of COC12 at 700 K is a 0 28 b 0 50 c 0 72 d 0 42

Which of the following is are correct for 0 1 M BOH solution K 10 5 pH of solution is 11 OH concentration is 10 3 mol L it s salt with HCl i e BCI forms acidic solution in water Phenolphthalein indicator can be used LIOL

Air at 20 C in a cylinder 0 15 m high and sealed by a piston is compressed reversibly and adiabatically to 2 cm Calculate the final air temperature answers below in degrees Celsius For air Cp 1 005 J g K and cv 0 718 J g K a 283 O b 299 C 324 d 369 e 383 f 401 9 444 h 461

Suppose a 500 mL flask is filled with 0 80 mol of H O 1 8 mol of CO and 0 20 mol of H The following reaction becomes possible CO g H O g CO g H g The equilibrium constant K for this reaction is 0 179 at the temperature of the flask Calculate the equilibrium molarity of CO Round your answer to two decimal places

What will be the total pressure of the gaseous mixture at equilibrium if AB is 20 dissociated according to the following reaction AB g equilibrium 1 4 Kp 2 7Kp1 2 3 2K1 2 1 2 A g 2B g Kp represents the constant of the reaction

WBS Year 3 e When N2 and H in the ratio 1 3 are allowed to react at 100 atm and 200 C it was found that the conversion to NH3 was 25 of original volume calculate Kp for the reaction N2 g 3H2 g 2NH3 g 4

d In a study of the water gas shift reaction CO2 g H2 g CO g H O g a mixture of CO2 and H2 initially containing 42 4 mol H2 was brought to equilibrium in a closed vessel at 1259 K The system was then found to contain 15 2 mol H Calculate Kp and AG for the reaction at 1259 K 3

WBSU Year 2017 5 d 20 85 g of PC15 is taken in a 4 L closed vessel at 250 C The equilibrium pressure of the mixture is found to be 1 825 atm Find out the partial pressure of Cl and the value of Kp 3

69 The degree of dissociation of 1 molecule of 1000 C and under atmospheric pressure is 40 volume If the dissociation is reduced to 20 at the same temp total equilibrium pressure c the gas is a 1 57 atm b 2 57 atm c 3 57 atm d 4 57 atm

e Does the equilibrium constant of a chemical reaction depend on the following i Standard states chosen for the reactants and products ii The stoichiometric representation of the reaction Justify your answer 2 2

It is generally accepted that a solution has useful buffer capacity pH change resisting power provided that the value of salt or conjugate base acid for acidic buffer lies within the range of 1 10 to 10 1 Buffer capacity is maximum when Conjugate base acid Calculate the pH of a solution made by adding 0 01 mole of HCl in 100 mL of a solution which is 0 2 M in NH3 and 0 3 M in NH4Cl pK NH3 4 74 log2 0 3

2 A B solid 2A g 3B g For the above hypothetical reversible balanced reaction at a particular temperature the value 3456 atm 5 Let the total pressure at equilibrium be x times as that of partial pressure of A Then find the value of 2x is

2 The question concerns the buffering effect of acid base system i What is the pH of a solution of that contains 0 15 M Na H PO4 and 0 65 M Na 2HPO4 ii iii What would the concentration of Na H PO4 be at pH 6 if 0 15M Na 2HPO4 was adjusted to that pH What would be the concentration of Na H PO4 be at pH 3 if the solution in ii was adjusted to that pH Please provide the rationale behind this calculation

Let 21 and 22 be the complex roots of ax 2 bx c 0 where a b c 0 Then A 21 22 1 8 121 22 2 1211 1221 1 None of these Question Let z1 and 22 be two roots of the equation 2 az b 0 z being complex Further assume that the origin z1 and z1 form an equilateral triangle hen A a b B a 2b 1 Point al 3b

Using the bond enthalpies in the bond energy values in KJ below calculate the Horxn For the combustion reaction of 2 moles of the following molecule C H O4 C H 413 C O 358 O H 463 C C 348 C O 799 O 495 diagram 4 OH a 3345 O b 4157 O c 5726 O d 2456 Oe 2678 CO OH

Example 7 13 Calculate the H3O of a solution having a pH of 10 6 Solution pH log H3O log H3O pH 10 6 Since mantissas are always positive in logarithmic tables therefore add 1 to the characteristic and 1 to the mantissa so that mantissa becomes positive log H3O 10 1 0 6 1 11 0 4 114 H O Antilog 114 2 5 x 10 1 mol L or

The activation energy difference for a reaction due to absence and presence of catalyst is 4 606 kcal at 1000 K temperature then ratio of 2 is K k and k are rate constants in the absence and presence of a catalyst respectively A e 100 C e 100 B 10 D 1

ii 0 187 moles of HA was put into solution and it came to equilibrium The final A 1 aq and H3O 1 aq concentrations at equilibrium were 2 67 x 10 2 M Determine the Kc iii The Ka for a strong acid is 3 x 103 If 1 5 x 10 3 moles of HA is dissolved in 1 liter of water then what will be the final concentration of A 1 aq

A sodium hydroxide solution is prepared by dissolving 5 0 g NaOH in 4 00 L of solution What is the molar concentration of OH in this solution What are the pOH and the pH of the solution What is the hydrogen ion concentration in this solution OH pOH pH Juti M

7 15 mL of a 0 105 M solution of NaOH is titrated with 0 116 M of HCI solution 5 0 mL of acid is added to the solution What is the pH of the solution 1 58 13 1 12 7 1 3

For the reaction A B 2C If the initial concentration of all the reactants species is 1 M each then the equilibrium concentration of C is 1M The value of Kc of the reaction is assume only reactant initially present in the reaction

When 12 0 mL of a 4 40 10 4 M aluminum acetate solution is combined with 25 0 mL of a 8 64 10 4 M ammonium phosphate solution does a precipitate form For these conditions the Reaction Quotient Q is equal to yes or no

37 Consider vaporization of CS according to the following equation CS2 1 CS2 g Calculate AG in kJ at the following conditions A 5 70 C 3 25 B 4 15 10 0 g CS 1 D 2 50 E 1 55 0 100 atm CS C

A gas AB3 present in 10 It container at pressure 2 5 atm and 273 K temperature On increasing the temperature to 546 K AB3 dissociates into AB g and B g If the degree of dissociation of AB3 is 0 8 then final pressure at 546 K is

Which of the following condition is are favourable for the production of NH3 g according to following reaction N g 3H g 2NH3 g assume system initially at equilibrium Increase in pressure of system Increase in volume of system Introduced more amount H g Introduced more amount N g

Consider an irreversible reaction A B C with a rate law R K A n B m d If B o were 2 mmol L t s A x 10 mol L B x 10 mol L 0 2 2 What would be the overall order of the reaction 1 10 1 1 20 1 2 1 2 What would be the order of the reaction with respect to A Unknown What would be the order of the reaction with respect to B Unknown 30 1 4 1 4

16 When AH and TAS both are negative then for spontaneous process which option is true 1 AH TAS 2 AH TAS X 3 AH TAS 4 AH AU Offion Ankach Tower 8 Pusa Road New Delhi 110

1 In an experiment 2 moles of HI are taken in an evacuated 5 0 litre container At 144 C the equilibrium constant is equal to 0 0156 for the gaseous reaction 2HI g H g I g Calculate the equilibrium concentrations of HI H and I

Question 38 For a zero order kinetics 2AP the initial concentration of reactant given is 0 05M The variation of degree of dissociation with time is denoted by the following graph a 8 time Using graph calculate value of rate constant x degree of dissociation tan 0 5 Initially only A is present A 0 125 B 0 0125 c 1 25 12 5