Homework Help for Chemistry

The H and 13 C[ H] NMR spectra for an unknown compound are shown below. Using these spectra and any additional information, determine the structure of the compound. Write the structure on each spectrum and then assign all resonances to the hydrogen or carbon atoms that give rise to these peaks. The molecular weight of this compound is: 114 1H NMR: Coupling constants and relative integrals are shown in parentheses next to each resonance.

The 'H NMR spectrum for an unknown cis or trans alkene is shown below. Using this spectrum and any additional information that is provided, determine the structure of the compound. Write the structure on the spectrum and assign all resonances to their corresponding hydrogen atom(s). Your structure must clearly show whether or not the alkene is cis or trans. In the given box briefly explain how you determined the geometry of the double bond. How did you decide on the geometry of the double bond? Be brief.

Identify the functional groups in the compounds that produced the 13C-NMR spectra pictured below.

Identify the functional groups in the compounds whose mass spectra are reproduced below.

Analyze each of the spectra below then propose a structure for the compound. In the mass spectrum the base peak is at an m/z = 43 with mi = 116. (Note: all of the spectra were produced by the same compound)

( G/ Ni) = plusminus mu i

Calculate the pH of a solution made by mixing 1 L each of 0.30 M acetic acid and 0.10 M sodium hydroxide. [pKa of acetic acid = 4.74] Calculate the pH change that occurs when 30 mL of 0.1 M NaOH are added to 200 mL of the solution in (a). Do you expect the pH change in (b) to be equal to the pH change when 30 mL of 0.1 M NaOH are added to 200 mL of 3.5 times 10-5M HC1? EXPLAIN. Calculate the pH change in (c). Is this what you expected? If not, can you find an explanation (i.e., do you think your prediction in (c) is wrong or do you think you "messed up" in your calculation)? Given that quantitative extraction should be at least 99.9%, answer the following: If the partition coefficient for a metal chelate partitioning between water and chloroform is 6.4, will quantitative extraction be achieved if a 25.0 mL solution of 4.3 times 10-2M ML (metal-ligand complex) is shaken with One 20-mL portion of chloroform Two 10-mL portions of chloroform Can you find the number of extractions needed to achieve quantitative extraction from the general formula? Suppose that a solute has a partition coefficient of 8.8 between water and chloroform. What volume of chloroform will be needed for a single extraction if the fraction of solute remaining in 25.0 mL of water is to be the same as the fraction remaining after three successive extractions with 10.0 mL portions of chloroform? How many grams of C^COONa should be added to one liter of 0.100 M HC1 to obtain an acid buffer with pH = 4.4. [You are given that pKa of acetic acid is 4.74] Using examples, explain how masking, de-masking, and pH control are used in EDTA titrations Explain how sulfate ion (as an example of an anion) can be analyzed via EDTA titration Ni2+ can be analyzed by back titration using standard Zn2+ at pH 5.5 with xylenoi orange indicator. A solution containing 25.00 mL of Ni2+ in dilute HC1 is treated with 25.00 mL of 0.05283 M Na2EDTA. The solution is neutralized with NaOH, and the pH is adjusted to 5.5 with acetate buffer. The solution turns yellow when a few drops of indicator are added. Titration with 0.02299 M Zn2+ requires 17.61 mL to reach the red end point. What is the molarity of Ni2+ in the unknown? In nature, hardwater tends to contain appreciable concentrations of Fe3+ and Cu2+. Explain how EDTA titration is used to determine hardness as Ca2+ and Mg2+ in the presence of these other metal ions.

Provide the starting materials needed to prepare the following Aldol products.

Obtain expressions for each of the following standard derivatives, for n moles of a monatomic ideal gas (express your results in terms of n, T, P, and/or R).