First – a word from our sponsors. The Oregon Natural
Resources Research Institute is working diligently to form a new
conception of everyday life, with the application of the scientific
method of questioning everything we know, without assumption. ONRRI
will work in tandem with the Organization for the Advancement of
Knowledge to provide direct support to communities that are growing
food on a local scale – in order to ease the transition from global
scale back to local scale. OAK and ONRRI can be found on-line
through NWETI.com – the Northwest Education and Training Institute.
NWETI provides on-line classrooms to teachers and students who wish
to prioritize learning by gaining common knowledge, as opposed to the
current school system which illuminates relationships by sequestering
information in the hands of a few.
Now back to water. Water does not live in a democracy
– each water molecule is created equal, but undergoes a change of
perspective that is completely different when bound to a biological
system, rather than hanging out with his buddies in a bulk water
system. Looking at the solution from he perspective of an individual
water molecule, we will explore the nature of change in different
environments to foster the idea of the ubiquity of possibilities of
what change can bring.
As we discussed before, water bonded in water with
other water molecules will have an average HOH bond angle of 109o
and an oxygen-hydrogen bond length of roughly one point five angstrom
units. The exact length is a measured average of many
individual measurements and changes constantly with vibrations.
The
essential parameters of a water molecule are the HOH bond angle and
the length of the two OH bonds. These bonds have a symmetric
stretching mode – both hydrogen atoms far away from the oxygen
together and near the oxygen together. There is also an asymmetric
stretching mode, which has two identical pairs of possibility –
left hydrogen near, right hydrogen far and left hydrogen far, right
hydrogen near. These stretches produce characteristic frequencies in
the Infrared Range (IR) of the electromagnetic spectrum. A Fourier
Transformed Infrared Spectrometer (FTIR) is an essential laboratory
tool for qualitative analysis of chemical elements – very high on
the current wish list for the ONRRI lab. FLIR is a flight oriented infrared scanning technique used to orient airplanes.
When water is attracted to ions – it shifts the
wavelength of the vibration of the water molecule. The whole idea of
spectroscopy is to measure the changes in spectra at different
wavelengths and correlate it to changes in the physical environment
of the atoms involved. When the solution color is in the visible
region of the spectrum, you can use a different type of spectrometer
– the UV-Vis , ultraviolet/visible light spectrophotometer– in
order to hone in on the wavelengths produced between 200 – 800
nanometers. Cary makes the workhorse instrument – the Spec 20,
that is a fixture in every high school chemistry lab in the land. If
the tools of chemistry sequestered at the schools could be made
available for general use, then people could learn hands-on that
chemistry is just a means of measurement.
So let's get back to our water solution and let's now
populate the solution with ions. Since Dr. Lenny worked in a Nickel
mine – let's use the Ni2+ ion as the example. Nickel
weighs 60 amu and is a transition metal – number 28 in the periodic
table. The periodic table is the collection of all elements placed
into a categorical form that allows for the prediction of chemical
behaviors based on composition. It is a basic tool for understanding
the language – each element has a symbol, a number and a weight
that make the calculations easier to handle. Chemistry involves a
lot of simple calculations like addition and subtraction,
multiplication and division. More complex math can be very useful –
but is not really necessary to being able to collect the information.
We will try to avoid all math in this series, but realize that the
numbers do have meanings beyond the scope of this simplified vision
of water.
Nickel ions form a green colored solution with six
water molecules that have a square planar geometry. [Ni(H2O)6]2+
. The oxygen of each water are oriented toward the central nickel
atom, four in a plane about the circumference of the nickel – then
one on top and one on bottom. The hydrogen atoms are oriented
outward from the center – with the oxygen of other water molecules
in the solution towards the center and the hydrogen arrayed outward.
Recall that the weight of the nickel ion is about the same as three
water atoms. The hydration sphere of the hexa-aquo nickel complex
depends on the temperature – but is likely five or six hundred levels deep
– each level fits more molecules around those connected – so we
have a sphere that is nearly 500 amu when two deep – you can see
where the actual weight of solvated ions adds up real quickly.
Nickel forms a red compound with dimethylglyoxime. The
formula is known to be Ni(dmg)2. By adding the nickel
containing solution to a dmg solution, we can quantitatively
precipitate the nickel and know exactly how much we had in solution.
We can also measure the concentration of a solution and correlate it
with the peak maximum of the red color in a Cary spectrophotometer.
The term aqueous solution is used to designate a
solution that is based in water. Free ions in solution always have
counter-ions in that solution to balance the charge. Thus the nickel
started as NiSO4 or NiCl2 and the reaction with
diglyme is a substitution type reaction. There are many different
metals that form cations in solution – the whole world of
coordination chemistry is a study of these types of systems.
When you consider the forces of polarity on the
micro-sphere scale – they appear to work the same way as the forces
of polarity on the human scale. Like attracts like in the form of
polar compounds like polar solvents – ionic compounds dissolve in
aqueous solution. The concentration of the solution is a measure of
the stuff dissolved in the water – this involves converting the
chemicals into moles, such that each chemical has it's molecular
weight factored into the chemistry equation.
Water does a lot more outside of the chemistry lab than
it does inside the lab. In the next nature of water episode, we will
explore the place where we find water. The differences between lakes
and streams and oceans and rivers will be explored with a large grain
of salt, in terms of what the water is composed with and how the
water thinks of itself.
Namaste' ... doc 04/11/13
No comments:
Post a Comment