Answer:
An appropriate solvent is <u>only in the fingerprint region. </u>
Explanation:
For scientists to study the infrared spectra of substances in the various states of matter, solutions are usually made with solvents. However, it has been noted that some of these solvents can interfere with the reaction spectra or be absorbed within the range of the solutes. A solution to this problem is using the right solvents with non-interfering infrared spectrum and which have no chemical effect on the solute.
The bands formed by the solvent should also be located in the the fingerprint spectrum. Examples of solvents used to achieve this and which meet up these requirements include, Carbon tetrafluoride and Carbon disulfide.
Half reaction: Cr₂O₇²⁻(aq) + 7H₂O(l) + 6e⁻ → 2Cr³⁺(aq) + 14OH⁻(aq).
Chromium change oxidation number from +6 in dichromate ion Cr₂O₇²⁻ to +3 in chromium cation.
Sum of the charges on the left side of the half reaction is -2 and on the left side is -8 (2·(+3) +14·(-1)), so six electrons must be added on the left side of half reaction.
Hydrogen bonds are not like covalent bonds. They are nowhere near as strong and you can't think of them in terms of a definite number like a valence. Polar molecules interact with each other and hydrogen bonds are an example of this where the interaction is especially strong. In your example you could represent it like this:
<span>H2C=O---------H-OH </span>
<span>But you should remember that the H2O molecule will be exchanging constantly with others in the solvation shell of the formaldehyde molecule and these in turn will be exchanging with other H2O molecules in the bulk solution. </span>
<span>Formaldehyde in aqueous solution is in equilibrium with its hydrate. </span>
<span>H2C=O + H2O <-----------------> H2C(OH)2</span>
