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