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Chemistry >> General Chemistry >> Redox Reactions and n factor Medical Exam

THE E0 VALUES OF FOLLOWING REDUCTn  Rxn  R GIVEN

Fe 3+ (aq ) + e ----> Fe3+ (aq)  E0= 0.771V

Fe2+(aq)  + 2e----> Fe (s) E0 =0.447V

WHAT WILL BE THE FREE ENERGY CHANGE FOR D Rxn ?

Fe3+(aq) + 3E----> Fe(s)

ans +11.87kJ/MOL.

Asked By: SARIKA SHARMA
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Joshi sir comment

Third reaction is the sum of 1st and 2nd so energy of 3rd will be the sum of energies of 1st and 2nd.

delta G = n1FE1 + n2FE2 = 1F(0.771) + 2F(0.447) = F(0.771+0.894) = 1.665F = 1.665*96368 = 160452.7 J = 38203.03 cal = 38.20303 cal

so total energy of the reaction 

Fe3+(aq) + 3e- -------> Fe(s) is 38.203 cal

and value of n = 3 so per mole energy = 38.203/3 

 

 

Chemistry >> General Chemistry >> Kinetic Theory of Gases Medical Exam

100 ml OF AN IDEAL GAS IS HEATED IN AN OPEN VESSEL FROM 300K TO 400K . THE VOLUME OF GAS THAT WILL REMAIN IN THE VESSEL IS =?

ANS) 100ML

Asked By: SARIKA SHARMA
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Joshi sir comment

its simple because question is based on volume and gas covers the complete volume of the vessel in which it is placed.

Chemistry >> General Chemistry >> Kinetic Theory of Gases Medical Exam

AT WHAT TEMP. THE r.m.s  VELOCITY OF OXYGEN WILL BE AS THAT OF METHANE AT 270 C ?

1) 540C

2) 327K

3) 600K

4)573K

Asked By: SARIKA SHARMA
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Joshi sir comment

v = {3RT/M}1/2

so according to the given condition 

{3RT/32}1/2 = {3R300/16}1/2

or T/32 = 300/16

or T = 600

so t = 600-273 = 3270C

Chemistry >> General Chemistry >> Mole Concept and Stoicheometry IIT JEE

Q. 1.Calculate the number of HCl molecules present in 10ml of 0.1N HCl solution.

Q.2. 4.0g of NaOH are contained in one decilitre of solutions. Calculate mole fraction. Molarity and molality of NaOH. ( Given, density of solution=                                                              1.038g/ cm3)

Q. 3. You are provided with 2 litre each of 0.5 M NaOH and 0.4M of NaOH solutions. What maximum volume of 0.30 M NaOH can be obtained from these solutions without using water at all ?

 

Asked By: HEMA RANI
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Joshi sir comment

1)   no of miligm eq. = 10*0.1 = 1

so no. of gm. eq. = 1/1000

since acid is monobasic so no. of moles = 1/1000

so molecules = 1/1000 * 6.023 * 1023

 

2)     0.1 litre soln. contains              4 gm. NaOH

       so 1 litre contains                      40 gm. NaOH

       so 1 litre soln. contains              40/40 moles of NaOH  = 1 mole so molarity = 1

 

 now 1 litre soln. contains                       40 gm NaOH

so 1*1038 gm soln. contains               40 gm. NaOH                   here 1038 gm/litre is density

so 1038 gm. soln. contains                  40 gm. NaOH

so 1038-40 gm. solvent contains        40 gm. NaOH

so 998 gm. solvent contains                 40 gm. NaOH = 1 mole 

so 0.998 Kg solvent contains                 1 mole NaOH

so molality = 1/0.998 

 

998 gm water contains                   40 gm. NaOH

so 998/18 mole water contains    40/40 mole NaOH

so mole fraction of NaOH = [40/40]/{[40/40]+[998/18]}

 

Third part is irrelevent without using water

 

 

 

Chemistry >> General Chemistry >> Mole Concept and Stoicheometry Medical Exam

IS BASICITY OF ACETIC ACID IS 1? PLS SEND THE BASICITY OF OTHER ACIDS WHICH ARE USUALLY ASKED  IN ENTRANCE EXAM

Asked By: SARIKA SHARMA
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Joshi sir comment

HCl, HNO3 , HCOOH are mono basic acids

COOH-COOH, H2SO4 are di basic acids

similarly others 

 

Chemistry >> General Chemistry >> Atoms and molecules Medical Exam

what is the relation b/w E1 &E2 whose respective wavelength r 400& 800 Ao . SIR I WANT TO KNOW THE RELATn b/w ENERGY & WAVELENGTH . ARE THEY DIRECTLY PROPTIONAL  ? ANS OF THIS QUES IS E1=2E2

Asked By: SARIKA SHARMA
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Joshi sir comment

E = hc/λ

so E is inversely proportional to λ 

Chemistry >> General Chemistry >> Atoms and molecules Medical Exam

THE FIRST EMISSION LINE IN THE ATOMIC SPECTRUM OF HYDROGEN IN BALMER SERIES APPEAR AT ?

ANS 5R/36cm-1

Asked By: SARIKA SHARMA
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Joshi sir comment

for balmer series of hydrogen atom 

 1/λ = R ( 1/22  -   1/32)     

solve for λ

Chemistry >> General Chemistry >> Atoms and molecules Medical Exam

IF n & l are principle & azimuthal quantum no. respectively then expression for calculating total no. of e- in any energy level is?

summation from l=0 to n-1 (2(2l+1)) HOW

Asked By: SARIKA SHARMA
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Joshi sir comment

for nth level values of l will be 0, 1,  2,  3, 4, 5, .....................(n-1) 

for l = 0   means s subshell no. of electrons = 2      = 2(2*0+1) 

for l = 1 means p subshell no. of electrons = 6        = 2(2*1+1)

for l = 2 means d subshell no. of electrons = 10      = 2(2*2+1)

similarly for others 

 

Chemistry >> General Chemistry >> Mole Concept and Stoicheometry Medical Exam

0.2 g OF SAMPLE OF H2O2  REQUIRED 10ml OF 1N KMnO4 SOLn  IN A TITRATION IN +NCE OF dil H2SO4 . THE % PURITY OF H2O2 IS?

ANS 85

 

Asked By: SARIKA SHARMA
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Joshi sir comment

No. of gm. equivalent of KMnO4 = No. of gm. equivalent of H2O2

so 1*10/1000   =     x  /  17             (17 is eq. wt. of H2O2) 

so  x = 0.17

so % purity = 0.17*100/0.2 = 85 

Chemistry >> General Chemistry >> Mole Concept and Stoicheometry Medical Exam

HOW MUCH WATER IS TO BE ADDED TO DILUTE 10ml OF 10N HCl TO MAKE IT DECINORMAL ?

ANS 100ml

Asked By: SARIKA SHARMA
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Joshi sir comment

N1V1 = N2V2

so 10*10 = 0.1*v 

or v = 1000 ml

so extra water added will be 990 ml

 

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