Micromeritics ASAP 2460, Operator'S Manual

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ASAP 2460 Operator’s Manual Appendix C
246-42800-01 - Aug 2013 C-9
Error of the BET Surface Area (m
2
/g):
Langmuir Surface Area
For each point designated for surface area calculations, the Langmuir
3
transformation is calculated as:
where L is in units of g/cm
3
STP.
A least-squares fit is performed on the ( P
rel
, L ) designated pairs where P
rel
is the independent variable
and L is the dependent variable. The following are calculated:
a.) Slope ( S g/cm
3
STP)
b.) Y-intercept ( Y
int
g/cm
3
STP)
c.) Error of the slope ( S
err
g/cm
3
STP)
d.) Error of the y-intercept ( YI
err
g/cm
3
STP)
e.) Correlation coefficient
Using the results of the above calculations, the following can be calculated :
Langmuir Surface Area (m
2
/g):
where
CSA = analysis gas molecular cross-sectional area (nm
2
), user-entered on the
Adsorptive Properties
window
BET
err
SA
bet
S
err
2
YI
err
2
+
 
0.5
Y
int
S +
-----------------------------------------------------------
=
L
P
rel
N
ads
----------
=
SA
Lan
CSA 6.023 10
23
  
22414
cm
3
STP
 
10
18
nm
2
m
2
-----------------------
 
 
 
S
-----------------------------------------------------------------------------
=