Re: Oxidation number of atoms in thiocyanate ion

photo_at_woelen.nl
Date: 10/23/04 

Date: 23 Oct 2004 11:06:17 -0700

farooq_w@hotmail.com wrote:
> photo@woelen.nl wrote:
>
> > This is new to me. I thought that oxygen bonding was limited to
> double
> > bonds. Is this third bond a real bond?
> triple bond = one sigma bond + two pi bonds.
I'll look up what this means for the distribution of electrons. My
knowledge of the different bonding types is buried deeply, although
once, I grasped the idea behind it.
>
> > > > For molecules like NO and NO2 I have the same problem when
making
> > Lewis
> > > > dot-structures,
>
> NO is said to have a bond order of 2.5(two double bonds + one odd
> electron)
>

>
> Can you do me a favor if you spare few minutes to solve this problem
> with a computer program to 8 decimal places, if it not so cubersome
for
> you. I just need to check, because neither I nor the the teacher have
> been able to get the correct answer perhaps the large number of
decimal
> places are required and rounding off gives a significant error.
>
> The system is:
> [Ca] 146.12 + [Ba] 193.66 + [Sr] 243.36 = 0.56246
> [Ca] 128.10 + [Ba] 175.64 + [Sr] 225.35 = 0.50980
> [Ca] 100.09 + [Ba] 147.63 + [Sr] 197.34 = 0.42730

The set of equations, you supplied is singular within the given
accuracy:
The singular value decomposition (SVD) of the matrix on the left hand
is
5.3546e+02
1.2642e+01
1.9671e-03
The largest eigenvalue of sqrt(AA') is more than 10^5 times as large as
the smallest one. This means that you loose approximately 5 digits of
significance, when determining the numerical solution of this system.
Because you only have 5 digits, one can safely state that this system
is singular within the given precision. The SVD shows that you have two
independent relations, the third one is just a combination of the other
2.

For your information:
The third equation can be written as eq3 = eq2 - a*(eq1 - eq2) within
the given accuracy of 5 digits, where a = 1.554384.
E.g. 100.09 = 128.10 - a*(146.12-128.10). The same relation exists for
all other coefficients.

Nevertheless, I can supply you with a solution, computed at 15 digit
accuracy internally, but I'm afraid this solution is meaningless:
[Ca] = 0.04362447
[Ba] = -0.08224782
[Sr] = 0.04156873

I'm wondering, don't you have computer hardware and software, with
which you can solve this type of problems? There are quite some good
open source products out there, such as Octave, pari/gp and libraries
like GSL.