Physical Chemistry Questions

27 Arrange the following compounds in the increasing order of their melting points Cl CI Cl I Cl a I II III c II CI b III 1 11 d CI 2 III

In a titration of Vinegar the average volume of 0 1 M NaOH used after three titrations is 4 26 mL If the density of vinegar acetic acid is 1 006 g ml and the molecular mass of CH3COOH is 60 05 g mol The mass percent m v of the vinegar is 1 5x10 5 2 5x10 4 3 0 5 4 5x10 3

On dissolving 0 6 g of urea molar mass 60 g mol and 1 8 g of glucose molar mass 180 g mol in 100 mL of water at 27 C The osmotic pressure of the solutionis R 0 08206 L atmk mol O O O 8 2 atm 2 46 atm 4 92 atm 1 64 atm

in the following diagram point X represents Vapour Pressure X A Boiling point of solution B Freezing point of solvent C Boiling point of solvent D Freezing point of solution 115 851 Temperature

CH CH C CH Hg OAc NaBHA O O O B H6 H O OH D Relation between A and B C and D are Position chain Position Functional Chain Identical C Matamor L CH CH CH CH HBr CC A HBr R 0 B

One mole of an ideal gas expands from 5L to 15 L at 300 K temperature against a constant external pressure 2 atm then Take 1 atm L O Enthalpy change of the gas 0 Change in internal riesgy at the grow it O Heat absorbed by the gas 2 kJ

b Explain why the Langmuir model describes Chemisorption better than Physisorption c The adsorption of a gas is described by the Langmuir isotherm with K 0 3 kPa Calculate the fractional coverage at a pressure 0 2 kPa Continued 369 5 4

A solution contains 0 100 M Ce 1 00 x 10 4 M Ce4 1 00 x 10 4 M Mn 0 100 M MnO4 and 1 00 HCIO4 For the following cell reaction calculate E and AG at the given conditions 5C e4 aq Mn aq 4H 0 1 0 193 V and 93 1 kJ 0 23 V and 111 kJ 0 02 V and 10 kJ 0 02 V and 10 kJ 5Ce aq MnO4 aq 8H aq

How many spectral lines will be observed in emission spectrum of hydrogen atom of Hy drogen atom is exposed with a monochrom atic light source for which energy of photon is 12 electron volt electron is present in gr ound state

Calculate the potential delivered by a voltaic cell using the following reaction if all dissolved species are 0 067 M and the pressure of H is 1 2 bar Zn s 2 H O l 2 OH aq Zn OH 2 aq H 8 Use the standard reduction potentials listed below Zn s 4 OH aq Zn OH 4 aq 2 e E 1 22 V 2 H O l 2e H g 2OH aq E 0 8277 Ecoll V

4 Which of the following pairings is incorrect in describing the spin states of d electrons in complexes Tetrahedral low spin Square planar low spin Octahedral Strong field ligand low spin Octahedral Weak field ligand high spin

Sachin was suffering from problem of he visited a physician who advised him to take 0 025 dm of milk of magnesia for a fast relief He exactly followed what the doctor told him to do Out of curiosity he saw the label on milk of magnesia bottle and he found that there were different ingredients written on it and the concentration of milk of magnesia mentioned was 29 ppm Assuming the volume of milk of magnesia required for neutralization of acid is equal to intake of milk of magnesia help Sachin to find out the following How many moles of acid was produced in Sachin s stomach i M Write down the neutralization reaction of this process Mg OH 2HCl MgCl 24 2728 iii Calculate the concentration of acid produced in mol dm

One half cell in a voltaic cell is constructed from a copper wire electrode in a 2 1 x 10 3 M solution of Cu NO3 2 The other half cell consists of a zinc electrode in a 0 25 M solution of Zn NO3 2 Calculate the cell potential You may need to use the following data Zn 2 aq 2 e Zn s E 0 763 V Cu aq 2 e Cu s E E 0 337 V 2 IT

Benzene diazonium chloride C H N C1 was decomposed in the presence of hypophosphorous acid and the nitrogen evolved after drying was found to be 36 9 ml at one atmosphere and 27 C The amount of salt taken must be nearly 481 mg 210mg 1 3 2 240mg 4 140 mg found to contain 40 mg Cat2

2 gm of a coal sample was heated at 120 C for one hour and residue weighed 1 815 gm Further the sample was heated at 950 C for 8 minutes The residue weighed 0 998 gm Finally the sample was heated at 750 C for 30 minutes and residue left was 0 512 gm Calculate percentage of moisture volatile matter fixed carbon and ash in the coal sample

One half cell in a voltaic cell is constructed from a silver wire electrode in a 0 10 M solution of AgNO3 The other half cell consists of a zinc electrode in a 0 025 M solution of Zn NO3 2 Calculate the cell potential E 0 763 V E Zn Zn Ag Ag 0 799 V

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

a Cs most metallic non radioactive element H e Mniimum atomic radius b Halogens p block alkali metals s block c Fluorine maximum ve electron gain enthalp y lodine minimum ve electron gain enthalpy

How much heat is evolved upon the complete oxidation of 6 g of aluminum at 25 C and 1 at 2Al2O3 s pressure for Al2O3 is 1676 kJ mol 4Al s 30 g Oa 85 59 kJ b 171 1 kJ Oc 342 3 kJ O d 9 238 x 10 kJ Oe 684 7 kJ

43 5 ml of 0 1 M Pb NO3 is mixed with 10 m of 0 02 M KI The amount of Pbl precipitated will be about B 10 4 mol 10 9 KG A 10 2 mol 5 ff 0 1 M Pb NO3 Phl A 10 mol G 24 G B 10 mol C 2x 10 mol 0 02 M KI 4 C 2 x 10 mol D 10 3 mol 431 26 AGRIG SKA D 10 mol

A cylinder contains nitrogen gas and some liquid water at the temperature of 25 C The total pressure found in the cylinder is 600 mm The piston is moved into the cylinder till the volume is halved keeping the temperature constant If aqueous tension at 25 C is 23 8 mm Calculate the final total pressure in the cylinder

One mole of an ideal gas expands under isobaric conditions If during expansion temperature of the gas increases by 1 C then work done by the gas is Cmp and Cm v are molar heat capacities at constant pressure and constant volume respectively Cm p O Cmp Cm v O Cm v Cm v Cm p

1 Through the reaction of zinc plus aqueous hydrochloric acid on a day when the temperature was 29 C and barometric pressure was 750 0 mm Hg 2 5 grams of hydrogen gas were collected over water What was the partial pressure of water in the collection flask A 30 7 atm B 15 4 atm C 0 95 atm D 0 039 atm E none of the above

50 g of dinitrogen N and 2 0 g of helium were enclosed in a vessel already containing 2 0 g of oxygen Calculate the total pressure and the fraction of the total pressure exerted by He The volume of vessel is 10 dm and the temperature is 300 K

Question 2 a Under what conditions is a dA 0 condition that defines the spontaneity of a process b A sample containing 2 50 moles of He 1 bar 350 K is mixed with 1 75 mol of Ne 1 bar 350 K and 1 50 mol of Ar 1 bar 350 K Calculate AGmixing and ASmixing

out of these LiCl has the highest lattice en ergy According to fajan s rule LiCI has the highe st covalent character But Ionic Character is directly proportional to lattice energy If LiCl has highest lattice e nergy shouldn t it have highest ionic charac ter

6 g of Zn Hg is dissolved in just sufficient amount of dil HNO3 and the solution s diluted upto 200 ml A Zn electrode is immersed in this solution and EMF of ne cell set up Zn Zn 2 aq H 1 N H2 1 atm Pt is 0 83 V The percentage f Zn in Zn amalgum is Given E2 0 77 V 2 303 RT 0 06 and atomic mass of F In 65 A 5 C 10 B 95 D 90

e t How many in the following are poor conductor of electricity Lemon juice Tap water Vinegar Distilled water Vegetable oil Sugar solution Milk Honey Soap solution Four 1 2 Five

3 3 S How much volume of HC1 43 by mass and specific gravity 0 9125 is required to completely neutralize 500 ml of 0 5N NaOH solution 1 25 ml 3 250 ml 50 ml of 2M H SO4 is titrated with 2 4 2 per mole to chloride and The remaining NaOH i ml of 0 1 N equil 4 23 25 ml 1250 ml

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

ne voltage E of the cell Ag s AglO s Agt x M HIO3 0 300M Zn 0 4M Zn s f Ksp E 3 10 8 for AglO3 s and K 0 15 for HIO3 Ag Ag 0 8 V E Given 2 303RT F A 1 17 V C 3 02V Zn Zn 0 06 0 76 V B 2 17 V D 1 43

0 01 mol of CH4 and 0 96 g of oxygen were enclosed in a flask maintained at a temperature 300 K The pressure inside the flask was found to be 101325 Nm 2 Calculate the volume of the flask Also tell what is the partial pressure of each gas

que ven below using the formula Po Ps Ps molality Molar mass of solvent 1 100 0 Calculate the mass of a non volatile solute molar mass 40 g mol which should be dissolved in 114g octane to reduce its vapour pressure to 80 b 20 g 10 g d 0 1 g a c 30 g

21 The dissociation energy of CH4 g is 360 kcal mo and that of C H6 g is 620 kcal mol 1 The C bond energy is 1 260 kcal mol 1 3 130 kcal mol 1 2 180 kcal mol 1 4 80 kcal mol 1

PART A Determination of Optimal Wavelength Wavelength nm Absorbance A 430 450 470 490 510 530 550 570 0 159 0 243 0 320 0 358 0 421 0 450 0 467 0 480 590 0 439

Question 1 a An ideal gas undergoes an adiabatic expansion into a vacuum Are AS AS surrounding and AStotal positive negative or zero Explain your reasoning b 2 25 moles of an ideal gas with Cv m 5R 2 are trans formed from an initial state T 680 K and P 1 15 bar to a final state T 298 K and P 4 75 bar Calculate for this pro cess AH AS

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

The change in concentration of a single reactant in a reaction as a function of time was followed The results of two experiments with different initial concentrations are shown in the figure on the right Estimate the value of the reaction order and the reaction rate coefficient Make sure you enter the correct unit for the reaction rate factor i know the pic is not the best but i really need your help sos tup jour A3

Forwarded What is the amount of phosphate buffer o pH 6 8 required to maintain the pH of the distilled water equals to its own pH when 100L of distilled water of pH 8 5 is present 10 46 pr

1 The solubility of salicylic acid in water is 7 8g 100ml at 100 C and 0 25g 100ml at 25 Estimate how much water is needed to recrystallize a 19g sample of salicylic acid A 150ml B 250ml C 300ml D 400ml

Cations Nati Nall Sodium Sodium Chlorida K 1 Potassium Cu 2 Copper Mg 2 Magnesim Ca 2 Calcium NH Ammonium 1 Ag Silver Chloride Al 3 luminium Oxide K 0 Potassium Oxide Sul sulphide Cu S Copper Sulphide Hydroxide Mg OH Magnesium 11 Hydrosude Nitrate Ca NO3 2 Calciumitrato Carbonate NH CO Ammonium Corborat S04 Sulphate POL Ag 504 Silver Sulphate Phosphate Alpon Aluminium Phosphate

2 From the following reactions determine which one represents a standard enthalpy of formation AH KCI s a K g Ch g b Mg s O g MgO s c CO g O2 g CO g d C s 2 H g CH4 g

OCI CI OF n basic aqueous medium the following graphs are plotted dx rate of disappearance of reactant and graph not to scale dt 3 5 601 moll sec 0 7 0 3 OH 2 4 2 8 log 1 mol L Keeping OCI and OH constant 1 5 1 0 2 2 2 7 log OH mol L Keeping 1 and OCI constant 0 4 0 2 2 4 2 6 log OCI mol L Keeping 1 and OH constant Now identify the true statement s about the above reaction A Order of the reaction w r t 1 is 1 B Order of the reaction w r t OCI is 1

For the reaction A g 2B g C g D g K A B dt nitial pressure of A and B are respectively 0 60 atm and 0 80 atm At a time when pressure of C is 0 20 atm rate of the reaction relative to the initial rate is A C 1 6 1 4 B D 1 48 1 24

5 How many grams of water would there be in 100 0 g of hydrate How many moles mass of water in 100 0 g of hydrate moles of water in 100 0 g of hydrate 6 How many grams of CuCl are there mass of CuCl in 100 0 g of hydrate 100 0 g of hydrate How many moles

In the reaction P g 2 Q g 4 R g 3 S I When 1 mole of P and 1 mole of Q are allowed to react to the completion of reaction then O All P will be consumed O 4 mole of R will form O 2 mole of S will form O All Q will consumed

Example 5 21 A toy balloon blown up at 5 C has a volume of 480 mL At this stage the balloon is distended to 7 8th of its maximum stretching capacity a Will the balloon burst if it is brought to a room having temperature at 30 C b Calculate the temperature at which the balloon will burst

The vapor pressure of benzene is expressed by the following formula 3884 K In P torr 17 63 T Calculate the boiling temperature of benzene when the atmospheric pressure is 500 torr A 340 2 K B 34 2 K C 273 15 K D 278 15 K

Example 7 11 How many grams of NaOH must be dissolved in one litre of the solution to have a solution of pH 12 Solution pH log H O 12 log H O 12 H3O 1 10 12 mol L 1 We know that OH Kw H O OH Kw H3O 1x 10 14 1x 10 12 1 x 10 mol L 1 Since NaOH is a strong base it is completely ionized NaOH OH 1 x 10 2 mol L 1 Molecular mass of NaOH 40 Amount of NaOH in grams per litre