Equilibrium Questions and Answers

4 Rate d N d H NH dt dt dt CKOO In the formation of sulphur trioxide by the cont process 250 g O g 250 g the rate reaction is expressed as d 0 2 5 x 104 mol L s dt The rate of disappearance of SO will be 1 5 x 10 mol L 2 2 25 x 10 mol L s 3 3 75 x 104 mol Ls 4 50 0 x 10 mol L s CKOO

3 1 7 x 10 3 The K for the reaction PC PCI Cl is 0 04 At a given time 0 1 mole PC 0 3 mole each of PC and Cl are present then predict direction of reaction 1 forward 3 at equilibrium 2 backward 4 None of these

2 decreases by 0 03 V 3 increases by 0 059 V 4 decreases by 0 059 V EC0062 How much will the potential of a hydrogen electrode change when its solution initially at pH 0 is neutralised to pH 7 1 increases by 0 059 V 2 decreases by 0 059 V 3 increases by 0 41 V 4 decreases by 0 41 V FC0063

N O42NO K 4 This reversible reaction is studied graphically as shown in the given figure Select the correct statements out of I II and III I Reaction quotient has maximum value of point A II Reaction proceeds left to right at a point when IN O 1 INO 0 1 M KQ when point D or F is reached concentration 1 I II B D G F Time 2 II III

3 The position of the equilibrium for a system when K 4 6x10 5 can be described as being favoured to the concentration of products is relatively 1 The right larger 3 the left larger 2 The left small 4 the right small

On addition of KF in the solution of 1 1 dissociation of HF increases 2 concentration of H ions increases 3 concentration of H ions decrease 4 concentration of F ions decreases

IE0134 112 pk for NH OH at certain temperature is 4 74 The pH of basic buffer containing equimolar concentration of NH OH and NH CI will be 1 7 74 2 4 74 3 2 37 4 9 26 JE0135

nd its salt the ratio o salt is increased 119 The pink colour of phenolphthalein in alkaline tion medium is due to Increases by one tenth Increases ten fold IEO 14 1 Negative ion 3 OH ions 2 Positive ion 4 Neutral form

0 14 mol of CO and 0 60 mol of NO2 are mixed in a 40 L reaction vessel at 200 C Calculate the molarities of all compounds present in the vessel once the equilibrium is reached CO g NO2 g CO2 g NO g Kc 67 5

How many of the following relations are correct for the solubility product Ksp solubility s g litre o sparingly soluble salt A3B2 producing A2 B3 ions mol wt M in water Assume no hydrolysis of any ion 1 Ksp 108s5 4 B 2s M 7 A2 1 M5 X 108s5 B 1 2 Ksp 5 8 B sp Ksp A 3s M 36s 2s M 1 M 54 S4 3 Ksp 3 A2 1 2 B 1 KSP B 13 vistigaorig 9 Ksp A2 2 B313 X 6 A 1 2 8

The solubility of Ag2CO3 in water is 1 26 x 10 4 mole litre What is its solubility in 0 02 M Na2CO3 solution Assume no hydrolysis of CO32 ion Take 2 1 26 A 5 x 10 6 M C 10 5 M B 50 10 6 M X D 2 10 5 M

3 The aqueous solution of FeCl is acidic becaus 1 Fe ions react with water to give H ions in solu 2 ions react with water to give H ions in solut 3 It is a salt of strong base and weak acid 4 None of these

4 Ba NO3 2 BaCl pH of when 50 mL of 0 10 M ammonia sol is treated with 50 mL of 0 05 M HCI solutio pk of ammonia 4 74 2 9 26 1 8 26 3 4 74

BUFFER SOLUTIONS and INDICATOR 08 In a buffer solution the ratio of concentration of NH Cl and NH OH is 1 1 When it changes to 2 1 pH of buffer 1 Increases 3 No effect 2 Decreases 4 None of these IF0131

184 Pre Medical Chemistry 109 To 50 mL of 0 05M formic acid how much volume of 0 10M sodium formate must be added to get a buffer solution of pH 4 0 pK of the acid 117

IE0133 111 In a mixture of weak acid and its salt the ratio of concentration of acid to salt is increased ten fold The pH of the solution 1 Decreases by one 3 Increases by one 2 Increases by one tenth 4 Increases ten fold 119 The F mediu 1 Ne 3 OF

Match List I Equations with List II Type of processes and select the correct option List I List II Type of processes Non spontaneous Equations a K Q b c K Q i AGO RT in Q ii d T 1 2 3 4 AH AS Options a iii iv ii i b iv i i ii Equilibrium iii Spontaneous and endothermic iv Spontaneous c ii ii iv iii d i iii iii iv

IEO128 6 Choose the wrong statement 1 For a neutral solution H OH Kw 2 For an acidic solution H K OHK K 3 For a basic solution H K JOH Kw 4 For a neutral solution H OH 10 M at all temperatures

iii In an aqueous solution of sulfuric acid the following equilibria exist H SO aq H O l H O aq HSO aq K very large HSO aq H O l H O aq SO aq K 0 012 moldm Explain in terms of these equilibria why the concentration of hydrogen ions in a 0 10 mol dm3 solution of sulfuric acid is not 0 20 mol dm No calculation is required

Marks 4 0 00 A solution contains 0 2 M NH4OH and 0 2 M NH4Cl If 1 0 ml of 0 001 M HCl is added to it x x 10 5 will be the OH of the resulting solutio Kb 2 x 10 5 Find value of x

During an adiabatic process the pressure of hypothetical ideal gas is found to be proportional to cube of its absolute temperature The value Cp Cy is x y Find sum

3 No effect on boiling point 4 None of the above CE0073 65 On cooling of following system at equilibrium COZ COzigi 1 There is no effect on the equilibrium state 2 More gas is formed 3 More gas is solidifies 4 None of above CE007

Marks 4 0 00 At 35 C the equilibrium constant for the reaction below is 2NOCI g 2NO g Cl g Kc 1 6 x 10 5 An equilibrium mixture was found to have the following concentration of Cl and NOCI Cl 1 2 x 10 2 M NOCI 2 8 x 10 M The concentration of NO g at equilibrium is x x 10 2 Find nearst integer value of x

ALLEN 93 In a solution of pH 5 more acid is added in order to reduce the pH upto 2 The increase in hydrogen ion concentration is 1 100 times 2 1000 times 101 H 1 fr

What is the concentration in molarity of H HCO3 and CO32 in a solution that is initially prepared as a mixture of 0 0100 M H CO3 and 0 000010 M Na CO3 Carbonic acid is a weak diprotic acid where Ka1 is 4 20 x 10 5 and K 2 is 2 00 x 10 6 a H at equilibrium b HCO3 at equilibrium c CO3 at equilibrium

A student assistant is given the task of preparing 2 00 L of a buffer whose pH is 9 00 She is given a 2 00 L aqueous solution of 0 10 M ammonia How much ammonium chloride NH CI must she add to the solution of ammonia Assume that the volume remains unchanged upon addition of ammonium chloride At 25 C the Kb of NH3 is 1 8 x 10 5

4 Nothing can be said List X A Active mass B Dynamic nature C A heat D log K K PP B AH 2 303R T T 41 CE0036 List Y 1 An 0 II Molar concentration III Vant hoff s equation IV adaptation if temperature increases E 2A g B g Correct match list X and Y 1 A V B II C II D I E IV 2 A V B IV C II D II E 1 3 A II B V C IV D II E 1 4 None of these 3C g v Chemical equilibrium

In 1 13 30 3 12 30 3 2 80 mol 4 3 74 mol The pH value of decinormal solution of Q 6 NH OH vt f NH OH which is 20 ionised is 2 14 70 4 12 95 3 2 80 mol 4 3 74 mol 20 3rfa za m 1 13 30 3 12 30 2 14 70 4 12 95

126 Pre Medical Chemistry 63 In a vessel containing SO SO and O at equilibrium some helium gas is introduced so that the total pressure increases while temperature and volume remain constant According to Le Chatelier principle the dissociation of SO 1 Increases 2 Decreases 3 Remains unaltered

In which of the following equilibrium reactions the equilibrium would shift to right side if total pressure is decreased 1 N 3H 2 H 3 N O 4 H Cl 2NH 2HI 2NO 2HCl

The equilibrium constant of the reaction Az g B g 2AB g at 373 K is 50 If 1L of flask containing 1 mole of A g is connected to 2L flask containing 2 moles B g at 100 C the amount of AB produced at equilibrium at 100 C would be 1 0 93 mol 3 2 80 mol 2 1 87 mol 4 3 74 mol Q 5 373 K 3T A g B g 2AB g en fer 50 1 af 100 C 1L 2 1 A g B g in kutute 2100 RAB 1 0 93 mol 3 2 80 mol 2 1 87 mol 4 3 74 mol

CE0066 9 For the manufacture of ammonia by the reaction N 3H 2NH 21 9k Cal the favourable conditions are 1 Low temperature low pressure catalyst 2 Low temperature high pressure catalyst 3 High temperature low pressure catalyst 4 High temperature high pressure catalyst

LE CHATLIER S PRINCIPLE Trans 2 pentene for th above equilibrium the value of standard free energ change at 400 K is 3 67 kJ mol If excess trans 2 pentene is added to the system then 1 Additional trans 2 pentene will form 2 Excess of cis 2 pentene will form 3 Equilibrium will proceed in the forward 4 Equilibrium will remain unaffected CE006 54 Cis 2 pentene

CE0061 Wessel Q is equilibrium reaction reaction e reaction ard reaction 60 CE0067 In the reaction 2Ag Big Cigl 362 kcal Which combination of pressure and temperature gives the highest yield of C at equilibrium 1 1000 atm and 500 C 2 500 atm and 500 C 3 1000 atm and 50 C 4 500 atm and 100 C 26

IE0096 79 The pH of a 0 1 M formic acid 0 1 dissociated is equal to 4 What will be the pH of another weak monobasic acid same concentration which is 1 dissociated 1 2 3 1 2 3 4 4 08

180 49 Pre Medical Chemistry If solubility of salts M X QY and PZ are equal then the relation between their K will be 1 K M X K QY K PZ 2 K M X K QY K PZ 3 K M X K QY K PZ sp sp 50 20

2 4 5 mol each of hydrogen and iodine heated in a sealed 10 litre vessel At equilibrium 3 mol of HI were found The equilibrium constant for Hz 12 2His 1 1 3 5 2 10 4 0 33 028080 BALTARGET

3 1 8 x 10 5 4 18 x 10 10 IE0060 52 At 25 C the volume of water required to dissolve 1g BaSO K 1 0 x 10 10 will be Molecular weight of BaSO 233 1 820 L 3 205 L 2 1 L 4 430 L 1500

creasing temperature favours forward CE006 6 In manufacture of NO the reaction of N and form NO is favourable if 1 Pressure is increased 2 Pressure is decreased 3 Temperature is increased 4 Temperature is decreased CF006

1 If the solubility product of AgBrO and Ag SO are 5 5x10 and 2x10 respectively the relationship between their solubilities can be correctly represented as 1 SA SA 50 2 So SAN 3 SA S 10 4 Unpredictable IE0083

Pre Medical Chemistry 123 In the reaction 2P g Q g 3R g S g If 2 mol each of P and Q taken initially in a 1 L flask At equilibrium which is true 1 P Q BUOL ID 2 P Q 14

7 In a chemical equilibrium A B C D when one mole each of the two reactants are mixed 0 4 mol each of the products are formed The equilibrium constant is 1 1 2 0 36 3 2 25 4 419

4 In the reaction PCI PCI Cl the partial 49 pressure of PCI Cl and PCI are 0 3 0 2 and 0 6 atm respectively at equilibrium If partial pressure of PCI and Cl was increased to twice what will be the partial pressure of PCI is in atm at new equilibrium condition 1 0 3 2 1 2 3 2 4 4 0 15 CE0050 50

Does Le chatelier s principle predict a change of equilibrium concentration for the following reaction if the gas mixture is compressed N O4 2NO2 1 Yes backward reaction is favoured 2 Yes forward reaction is favoured 3 No change 4 No information C50060

5 The dissociation of CO can be expressed as 200 200 0 If the 2 mol of CO is taken initially and 40 of the CO is dissociated completely What is the total number of moles at 2 2 0 3 1 2 equilibrium 1 2 4 4 5 CF0039

completely What is the total number of moles at equilibrium 1 2 4 3 1 2 1 a 3 36 In A g 3A g reaction the initial concentration of A is a mol L If x is degree of dissociation of A The total number of moles at equilibrium will be ax wo 2 ax 2 2 0 4 5 CE0039 4 a 2 ax 40

f IE0069 59 One litre of saturated solution of CaCO is evaporated to dryness when 7 0 g of residue is left The solubility product for CaCO is 1 4 9 10 2 4 9 x 10 3 4 9 10 9 4 4 9 x 10 7 IE0070

Pre Medical Chemistry 179 3 Ionisation constant of a weak acid is 10 Find out equilibrium constant for the reaction of this weak

45 a mol of PCI undergoes thermal dissociation as PCI Cl the mole fraction of PCI at PCI equilibrium is 0 25 and the total pressure is 2 0 atm The partial pressure of Cl at equilibrium 51 is 1 2 5 3 0 5 2 1 0 4 None CE0051 46 In a 0 25 L tube dissociation of 4 mol of NO takes

3 Ke for the esterification reaction CH COOH C H OH CH COOCH0 H O is 4 If 4 mol each of acid and alcohol are taken initially what is the equilibrium concentration of the acid 1 2 3 3 13 3