Dimethylamine, (CH3)2NH, is an organic base with pKb= 3.23at 298 K. In an experiment, a 40.0 mL sample of 0.105mol/L-1(CH3)2NH(aq)is titrated with 0.150mol/L-11HI(aq)at 298 K.

(a) Write a balanced chemical equation for the neutralization reaction upon which this titration is based, and indicate clearly which atom is being protonated. Then, calculate the equilibrium constant for the neutralization reaction. (Hint: To calculate the equilibrium constant, you may find it helpful to represent the neutralization reaction as the sum of twoor morereactions.)

(b) Calculate the pH, [(CH3)2NH], and[(CH3)2NH2+] at the following stages of the titration. Justify any approximations.

i) before the addition of any HI solution

ii) after the addition of 20.0 mL of HI solution

iii) at the equivalence point

iv) after the addition of 60.0 mL of HI solution

Quantitiy of limiting reagent= 13.5 mmols salicylic acid

Based on the quantity of the limiting reactant used above, what is the theoretical yield of the aspirin (acetalsalicylic acid) product, in grams?

The following multipart question involves many electron atoms and their emission spectra.

a. What term symbols can arise from the [He]2s²2p¹3d¹ excited configuration of carbon (include the multiplicity and the J level)?

b. What is the term with the lowest energy and why?

c. What are the possible allowed transitions between the given term symbols?

d. What are the selection rules for many electron atom spectra? Give an example of a forbidden transition between term symbols and the selection rule that is broken by the forbidden transition.

Can you make a seperation scheme for this Tetraphenylcyclopentadienone lab ? Please use the procedure below to make it. Thank you.

Procedure:

Add 1.5 g benzil, 1.5 g dibenzyl ketone, and 12 mL absolute ethanol to a 50-mL round-bottom flask. Place a magnetic stir bar in the flask. Attach a condenser, having lightly greased the joint. Stir and heat the mixture at 70ºC until the solids dissolve. Then raise the temperature to 80ºC with continued stirring. Using a 9" Pasteur pipette, add dropwise 2.25 mL of ethanolic potassium hydroxide solution through the condenser into the flask; make an effort to prevent any drops from contacting the condenser walls . The mixture will immediately turn a dark purple. Once you have added the potassium hydroxide, raise the temperature to about 85ºC. Stir the mixture at this temperature for 15 minutes.

At the end of the heating period, remove the flask from the heat and allow it to cool to room temperature. Then place the flask in an ice-water bath for 5 minutes to complete the crystallization of the product. Collect the deep purple crystals on a Büchner funnel by vacuum filtration. Wash the crystals with 3 4-mL portions of ice-cold 95% ethanol; this wash solvent should be used to transfer crystals from the round-bottom flask to the Büchner funnel if they do not all come out when the mixture is initially poured into the funnel. After air-drying the crystals for a few minutes, complete the drying in a 100ºC-oven for a few minutes.

Weigh the dried product and calculate the percent yield. Also calculate the overall percent yield from benzaldehyde. Determine the melting point. If the melting point is not within 2ºC of the literature value, you should recrystallize your product

Recrystallize your tetraphenylcyclopentadienone from a 1:1 mixture of 95% ethanol and toluene; approximately 24 mL of this solvent mixture will be required per gram of tetraphenylcyclopentadienone, but remember to only add the minimum boiling solvent necessary to dissolve the solute. Recover the crystals by vacuum filtration and redetermine the melting point.

I performed an electrophilic aromatic substitution- iodination of salicylamide.

I used 1.012 g of solid salicylamide in 20 mL ethanol. 1.205 g of sodium iodide was also added. Then I placed the solution in an ice bath for 5 min and after this time 7.0 mL of 8.25% NaOCl was added.

What is the expected product and why?

(At the end of lab, and IR was obtained and this indicated the product to be a 1,2,4-trisubstituted aromatic compound).

What is the identity of the product and was it the same as the expected? What is the theoretical yield?

What is the freezing point of a 50% by volume ethanol solution? Assume water is the solvent. (Use data from Table 12.7 in the textbook.)

For water:

Kb = 0.512 °C m−1

You have completed a reaction and take the melting point of your resulting solid product and the melting point you measured on the melt-temp is 130 – 142°C. The product you were trying to make was chloramphenicol which has a literature melting point of 150 - 151.5°C.

(A) What are two possibilities for why your melting point is different from the literature melting point?

(B) How would you figure out which of your two possibilities actually happened?

Step by Step

Given the following analysis of ground water:

Ca²⁺    43.12 mg/L          SO₄^2-     13.22 mg/L

Na⁺     87.15 mg/L          Cl^-         123.89 mg/L

K⁺       3.22 mg/L           HCO₃^-   213.7 mg/L

Mg²⁺   15.22 mg/L          NO₃^-     3.23 mg/L  

Fe²⁺ 2.13 mg/L            pH       8.3

(A)   Convert all values to meq/L.

(B)    Do an anion-cation balance.

(C)   Plot the position on a trilinear diagram (below)

(D)   Make a Stiff pattern of the analysis (on regular graph paper)

(E)    Make a Schoeller diagram of the analysis (use semi-log)

At 25 ∘C the reaction from Part A has a composition as shown in the table below.

What is the free energy change, ΔG, in kilojoules for the reaction under these conditions?

Express your answer numerically in kilojoules.

a.) Proteins A and B with molecular weight of 16,500 and 35,400 move 4.60 cm and 1.30 cm respectively, during electrophoresis and in SDS-polyacrylamide gel. What is the molecular weight of protein C that moves 2.80 cm under the same conditions in the same gel?

b.) The sedimentation coefficient of a DNA molecule is 22.0 S. A dilute solution of the DNA is spun in a centrifuge at 40,000 rpm starting from a distance of 6.0 cm from the axis of rotation. How far will the DNA move in 20 min?

Calculate the mass of methane that must be burned to provide enough heat to convert 300.0 g of water at 30.0°C into steam at 106.0°C.

50mL of 0.010M NaOH were titrated with 0.50M HCl, added with a dropper pipet. If each drop has a volume of 0.040mL, calculate how many drops of HCl are needed to reach the end-point of the titration.