- Organic Chemistry
- Aldehydes and Ketones
- Alkyl Halides, Alcohols and ethers
- Amines and other nitrogen compounds
- Aromatic Chemistry
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- Carboxylic acids and its derivatives
- Chemistry in daily life
- General Mechanism in organic compounds
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102 - Physical Chemistry Questions Answers
in the crystal str of Fe3O4 Fe2+& Fe3+ occupy resp.
50% octatrahedral &12.5% tetrahedral viods
let atom of O = 1
so 50% Fe++ in octahedral void = 1*1/2 = 1/2
and 12.5 % Fe+++ in tetrahedral voids = 2*1/8 = 1/4
so total Fe = 1/2 + 1/4 = 3/4
so name of the compound = Fe3/4O = Fe3O4
d possible types of two dmensional lattice &3 D primitive unit cells are resp.
ans 5& 7
and in 3 D these are 7 crystal system, I have given an article for these 7 already
how many atoms are there in a cubic unitcell having one atom on each corner &two atoms on each body diagonal of cube?
& also if instead 2 there are 3 atoms at body diagonal?
corner atoms = 8*1/8 = 1
diagonal atoms = 4*2 = 8
total = 9
in second case calculate similarly
Emf of the cell Ni/Ni+2||Au+3/Au at 298 K will b? [EoNi/Ni+2 = 0.25 V,EoAu/Au+3= -1.5V]
Ecell = E0cell - (0.0591/n) log {[Ni++]3 / [Au+++]2}
Reactions are 3Ni ------> 3Ni++ + 6e-
and 2Au+++ + 6e- ----------> 2Au
now put E0cell = E0c - E0a = 1.5 - (-0.25) here you should remember that you have to take only reduction potentials not oxidation potentials
= 1.75
n = 6 and concentrations if given otherwise take these two equal to zero.
IF D POSITn OF Na+ & Cl - rR INTERCHANGED IN NaCl having FCC ARRANGEMENT OF Cl- THEN IN D UNIT CELL OF NaCl
Na + WILL INCREASE BY 1 WHILE Cl- DECREASE BY 1
PLS TELL D REASON
No,
These will be no change by making this type of change
THE PYKNOMETRIC DENSITY OF NaClis 2.165X 10-3 wHILE ITS Xray density IS 2.178X103 kgm-3 the fraction of unoccupied sites in NaCl crystal is?ans) 5.96x 10-3. how we will caculate this fraction
Pyknometer is a device to measure density of substance. Density measured by pyknometer is called pyknometric density. In porous solids this density may be different from true density of solid if the liquid used is unable to fill the pores of solid.
I think that the first density will be 2.165 * 103
difference of density = 2178-2165 = 13 kg/m3
so fraction of unoccupied site = 13/2178 = 5.96 * 10-3
CRYSTALLINE SOLIDS HAVE
a) SHORT RANGE ORDER
b) ANISOTROPIC DISTRIBUTn
c) LONG RANGE ORDER
D) NO ORDER
AIIMS2001
SIR AS WE KNOW THAT BOTH THE OPTION B) & C) ARE CORRECT BUT IN THIS QUES WHICH OPTn WOULD BE MORE APPROPRIATE FOR CORRET ANS
.
According to me it should be b
for anisotropic character is a basic property of crystalline solids
two flasks A and Bcontain helium and hydrogen gases at 270C and 1 atm pressure. If volume of each vessel is 2L then flask B contains....
(1) The same number of atoms as in B , (2) same weight of gasas in B , (3) dubble the number of atoms asin A (4)half of the number of atoms in A , ?
answer by nikhil is correct
in his answer Na represents avagadro number not sodium
Q IN THAT Fe QUES ANSWER GIVEN IS -VE 0.405 BUT ACC. TO THIS METHOD ANSWER DO NOT MATCH
Q I STILL DIDNOT UNDERSTAND CO & CO2 RELATION
Fe -----> Fe++ + 2e-
so E for the new reaction = [1F(0.77) + 3F(0.04)]/2F = 0.89/2 = 0.445
so it will be -0.445 for the reverse, you are asking for reduction and i submitted the answer for oxidation so the duality created.
according to the given reaction we get 2L monooxide by 1L dioxide,
initially litres of CO2 = x so it will form 2x litres of CO
and 1-x litres CO are present from the start so total litres of CO = 2x+1-x = 1+x
IN QUES OF RXn Fe 2+ + 2e- ---> Fe THE E* GIVEN IS -VE 0.405 &I WANT TO KNOW IN THE LAST STEP WHY3/2F(0.4) IS USED
IN RXn CO2 +C---> 2CO IN INITIAL WE TAKE XFOR CO2 BUT FOR FINAL Y 2X +1 -X=1.2 IS USED.
for any reaction obtained by other two reactions formula used will be nE = n'E' + n''E''
in second question 2x is used because x litre CO2 will give 2x litre CO