102 - Physical Chemistry Questions Answers

10 ml of M/200 H2SO4 is mixed with 40 ml of M/200 H2SO4. The ph of the resulting solution is

Asked By: SWATI KAPOOR
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Joshi sir comment

M of H2SO4 = 1/200

so [H+] = 2*1/200 = 1/100 = 10-2

now calculate pH

 

 

 

The pH of solution at 25°C which has twice as many hydroxide ion as in pure water at 25°C , will be

Asked By: SWATI KAPOOR
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Joshi sir comment

no of hydroxide ion in pure water = 10-7

so according to the given condition no. of hydroxide ions in solution = 2*10-7

so pOH = -log2*10-7

so pH = 14 - pOH 

The ph of 0.1 M HCN is 5.2. What is the Ka?

Asked By: SWATI KAPOOR
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Joshi sir comment

HCN ------------------->  H+ + CN-

0.1                                 0          0

0.1-x                              x           x

pH = 5.2

so -log[H+] = 5.2 

solve for [H+], it will give x

then calculate Ka

 

ΔHf  C2H4 = 12.5 kcal

Heat of atomization of C = 171 kcal  

Heat of atomization of H = 52.1 kcal  

Bond energy CH = 99.3 kcal .

What is C=C bond energy?

Asked By: SWATI KAPOOR
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Joshi sir comment

2 heat of atomization of C + 4 heat of atomization of H - 4 bond energy of C-H - 1 bond energy of C=C = heat of formation of C2H4

2*171 + 4*52.1 - 4*99.3 - x = 12.5

solve

How Is the value of n calculated for nerst equation??

 

Asked By: AAYUSH TANEJA
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Joshi sir comment

n is the no. of electrons in anode or cathode reaction.

If no. of electrons are different then make these no. common

for ex. if reactions are 

             Al ---------------> Al+++ + 3e-

and     Cu++ + 2e- ------------> Cu

then multiply (1) to 2 and (2) to 3

after that electrons will be 6 in both reactions so n = 6

Integral enthalpy of soln of KCl , when 1 mole of it is dissolved in 20 mole water is +15.90kJ . When 1 mole of it is dissolved in 200mole water  dH =15.58kJ. Calculate enthalpy of hydratn or dilutn ??

 

ans is 2.68kJ

Asked By: SARIKA
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Joshi sir comment

Integral enthalpy 

please check this word if wrong submit the correct question again

show that (du/dv)s=T-sdp

 

Asked By: KARTHIKCHEMIST
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Joshi sir comment

question is incorrect 

because (du/dv)s represents pressure and T is temperature

Chemistry >> Physical Chemistry >> Solutions Engineering Exam

q. = Mass of solution of 1 molal glucose solution to get 0.2 molal glucose is.

a.200

b.300

c.236

d.108

Asked By: NIRMIT MAHESHWARI
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Joshi sir comment

I think question is incomplete, correct it first

acetic acid in a solvent undergoes 20% dissociation and 70% association, find vant hoff factor. 

Asked By: TABREZ
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Joshi sir comment

CH3COOH  = CH3COO- + H+

     1                     0                 0

    0.8                 0.2               0.2

CH3COO- + H+ = CH3COOH

0.2             0.2               0.8

0.06            0.06           0.8+0.14

0.06             0.06              0.94                      sum = 1.06

so i = 1.06/1 = 1.06 

 

 

 

 

calculate the molecular weight of cellulose acetate if its 0.2%wt/vol solution in acetone(sp. gravity 0.8) shows osmotic rise of 23.1mm against pure acetone at 27C.

Asked By: HEMA RANI
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Joshi sir comment

By formula πV = nRT

π = hdg, n=w/M

given 

0.2%wt/vol solution in acetone means w= 0.2 gm, V = 100 ml= 100/1000 litre = 0.1*10-3 m3 ,   h = 23.1/1000 m, d = 800 kg/m3 ,  

now solve

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