102 - Physical Chemistry Questions Answers

what is the ph of the solution formed by mixing 20 ml of 0.05 M H2SO4 with 5 ml of 0.45 M NaOH at 298 k ?

Asked By: SAMREEN KOUR
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Joshi sir comment

mili eq of acid = VN = 20*0.1 = 2

mili eq of base = VN = 5*0.45 = 2.25

total milieq = 2.25-2 = 0.25 of base in 25 ml

so N = 0.25/25 = 10-2

so pOH = 2 so pH = 12

1-In the following hypothetical reaction A + 3B --------------

 2C + D, initial moles of A is twice that of B. If
at equilibrium moles of B and C are equal, % of B reacted is?
Asked By: SHWETA BHARDWAJ
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Joshi sir comment

     A + 3B ---------> 2C + D

     1    1/2                0     0

    1-x   1/2-3x          2x    x

according to the given condition 1/2 - 3x = 2x

                                        so 1/10 = x

so 3x = 3/10

so % = 0.3*100/0.5 = 60

The following data was obtaind for the vapour phase decomposition of ethylene oxide into methane and carbon monoxide at 414.5'c. t,min p,mm hg 0 116.6 5 122.56 7 125.72 9 128.74 12 133.23 18 141.37 show that the reaction is first order and calculate the rate constant.
Asked By: BIBHUTI BHUSAN PADHI
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Joshi sir comment

                      C2H4O -------------->           CO           +           CH4

          t                                          P (C2H4O)

         0                                          116.6

         5                                          116.6-[122.56-116.6] = 116.6-5.96 = 110.64

         7                                           116.6-[125.72-116.6] = 116.6-9.12 = 107.48

   similarly others then find k for different readings by first order equation. k will be same for all readings.

       

why heat of an ideal solution is taken as zero ?

Asked By: H. SHASHANK KUMAR
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Joshi sir comment

because in ideal solution there is no interaction between the two liquids present in the solution

The enthalpy of nuutralisation of  a strong acid HA and weaker acid HB by KOH are -13.7 and -12.7 kcal/eq. When one equivalent of KOH is added to a mixture containing 1 eq of HA amd HB ; the enthaply change was -13.5 kcal. In what ratio is thge base distributeed between HA and HB ?

Asked By: H. SHASHANK KUMAR
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Joshi sir comment

let x in HA and 1-x in HB

so according to the given condition -13.7x-12.7(1-x) = -13.5

solve

Why gas in gas not a solution
Asked By: JASEEM A RAHMAN P
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Joshi sir comment

gas in gas is a solution but interaction between the molecules play almost no role so these solutions are addressed as mixtures

WHAT OSMOTIC PRESSURE WOULD BE OF 1.25m SUCROSE SOLUTION AT 25C ?DENSITY OF SOLUTION IS 1.34g/mL?

Asked By: SHWETA BHARDWAJ
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Joshi sir comment

formula is πV = nRT or π = MRT,   M is molarity

strength of solution is 1.25m

so 1000 gm water ..............................................1.25 mole sucrose

so 1000 gm water .............................................1.25*342=427.5gm sucrose

so 1427.5 gm solution ....................................1.25 mole sucrose

so 1427.5/1.34=1065.30 ml = 1.0653 L solution ...........................1.25 mole sucrose

so M = 1.25/1.0653

put all the values to get answer.

 

when 20 g of caco3 were put into 10 litre flask and heated to 800 degree cesius, 30% of caco3 remained unreacted at equilibrium. kp for decomposition of caco3 will be 1.231 ATM    HOWWWW............PLS SOLVE THIS ....PLS PLS..........

Asked By: PRATIBHA
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Joshi sir comment

CaCO3     ---------->   CaO   +   CO(g)

0.2 mole                   0            0

0.06                       0.14       0.14

so Kp= p                       only CO2 is gas so its pressure is considered 

now p = 0.14*0.0821*1073/10 

now solve

0.25 g lyophilic colloid is added to 100 ml gold solution to prevent the coagulation on adding 1ml 10% NaCl soln . What will be gold number of lyophilic colloid??

Asked By: SARIKA SHARMA
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Joshi sir comment

 “weight of the dried protective agent in milligrams, which when added to 10 ml of a standard gold sol (0.0053 to 0.0058%) is just sufficient to prevent a colour change from red to blue on the addition of 1 ml of 10 % sodium chloride solution, is equal to the gold number of that protective colloid.”

 

0.25 g lyophilic colloid is added to 100 ml gold solution

so 250 mg lyophilic colloid is added to 100 ml gold solution

so 25 mg lyophilic colloid is added to 10 ml gold solution

so answer will be 25

Most effective coagulant for a colloid soln of arsenic sulphide in water is

1) 0.1 M sodium phosphate

2) 0.1M zinc sulphate

3) 0.1 M zinc nitrate

4) 0.1 M aluminium chloride

Plzz annex explanation also

Asked By: SARIKA 19 Day ago
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Asked By: SARIKA SHARMA
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Joshi sir comment

its 4th option 

because As2Sis usually a negative colloid and positive ion is responsible for its coagulation and according to Hardy Schulze priciple more positive ion will be more effective

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