Parr Instrument 1356 - Manual (Page 22)

22
4. Nitrogen
1.251 gm x 10.8 liter = 13.51 gm
.249 cal x 13.51 gm = 3.36 cal
gm K K
oxygen 3.4 cal/C
argon 2.4 cal/C
helium 2.4 cal/C
nitrogen 3.4 cal/C
ISO/BSI Bomb Washing Titration
The reaction is carried out stoichiometricly to a phenolpthalein endpoint (V2)
(2HNO3 +H2SO4) +2 Ba(OH)2 + 4H20
Excess Na2C03 (20 ml 0.1N) is back titrated with HCl using methyl orange (V1)
Ba(NO3)2 + Na2CO3 (excess)=BaCO3 (P) + 2NaNO3
Assume heat of formation of H2SO4 is _72 kcal/mole(-301kJ/mole)
Assume heat of formation of HNO3 is –14 kcal/mole (-59.8kJ/mole)
Mwt. H2SO4=98, eqwt=49
Mwt HNO3=63
4.184J=1 calorie
So, for H2SO4, 301 kJ/mole*0.1N/2*0.001liter=15.1 J.ml of 0.1N H2SO4
For HNO3 59.8 kJ/mole*0.1N*0.001 liter=5.9J/ml of .1N HNO3. (ISO uses 6 J/ml
ISO calculations
Nitric acid correction in joules:
5.9*(20-V1)
Sulfuric acid correction in joules:
15.1*(V1+V2-20)
Add them:
7.2 V1+ 15.1 V2-184