Parr Instrument 6772 User Manual
Page 51
6772
Calorimetric Thermometer Instruction Manual
6-4
Acid Multiplier Calculation:
0.0709
formation
HNO
to
due
calories
HNO3)
of
HNO3)(H
of
valents
(milliequi
HNO
of
alents
milliequiv
SO
H
of
alents
milliequiv
-
alents
milliequiv
acid
Total
3
f
3
4
2
=
=
=
Sulfur Correction:
e2 = (percent sulfur)(sample mass)(sulfur multiplier)(heat of formation of H2SO4).
Acid Correction:
In the 6772 there are a number of settings for the acid correction.
e1 is the nitric acid portion of the correction.
Fixed HNO3: The Acid Correction is a fixed value set by the operator.
The calculation is:
e1 = (nitric acid value)(acid multiplier)(heat of formation of nitric acid)
For an 1108 bomb the default nitric acid value is 10 and acid multiplier is .0709. The
heat of formation of nitric acid is 14.1 calories/milliequivalent so the calculation is:
e1 = (10)(.0709)(14.1) or e1 = 9.9969 (rounds to 10) calories.
When the Acid Correction is set to Fixed HNO3 the value is considered a final value
and the operator is not prompted for an acid value when reporting the results.
Entered HNO3: The Acid Correction is entered by the operator when reporting the
results.
The calculation is the same as Fixed HNO3 above. The value listed on the Acid
Correction button is used for preliminary calculations. When finalizing the report the
operator will be prompted for the acid value.
Fixed Total: The Acid Correction represents the total base required to titrate the
bomb washings (in milliliters). This includes both nitric and sulfuric acid. The
correction is a fixed value set by the operator.
The calculation is:
e1 = [((total acid)(acid multiplier)) – (% sulfur)(sample mass)(sulfur multiplier)](heat
of formation of nitric acid)
Using the default acid and sulfur multipliers as well as a heat of formation of nitric acid
of 14.1 cal/milliequivalent a 1 gram sample with 25 ml of washings and 2 % sulfur
would result in the following calculation: