Starting with 7.2 g of salicylic acid, how many grams of acetylsalicylic acid (theoretical yield) can be made? Assume salicylic acid is the limiting reagent and a one to one stoichiometry. Use the molecular weights that you have already calculated. Give two significant digits.

A sample of THAM primary standard base weighed 0.9180 grams. After dissolving in 100ml deionized water and adding four drops of brom-cresol-green indicator, an HCl solution was added gradually until a definite color change was observed. At this point, 28.20 ml of HCL solution had been drained from the buret. Using the equation for the overall reaction, calculate the molarity of the HCl

Q1. A compound was characterized using UV-visible absorption spectroscopy. The absorbance spectrum of a 1.00 x 10–4 mol/L solution in a 1.00 cm path length cell peaked at the wavelength of 345 nm to a value of 1.32.

(1) What was used as a reference? Specify the cell and its contents.

(2) What is the transmittance at that wavelength?

(3) What is the molar absorptivity at that wavelength?

Q2. Answer the following questions regarding quantitative analysis using UV-visible spectroscopy. Assume that the spectrometer gives you the raw intensity spectrum of the transmitted light as a function of the wavelength only, and the light source is stable.

(1) You are given a water-soluble compound. Explain how you can obtain the spectrum of specific absorption coefficient ε(λ) = Abs/(bc), where Abs is the absorbance spectrum, b is the path length, c is the mass concentration (wt% or g/mL).

(2) Let us assume that you have obtained specific absorption coefficient εa(λ) and εb(λ) for two water-soluble compounds a and b having different colors. You are given a mixture that consists of the two compounds and a third transparent compound. How can you find the concentrations of and b (ca and cb, respectively) when the total concentration of the mixture in water is c (c > ca + cb). Explain the procedure.

Determine the pH of an HF solution of each of the following concentrations.

Part A: .280 M

PartB : 4.5*10^-2 M

Part C: 2*10^-2

Part D

In which cases can you not make the simplifying assumption that x is small?

In which cases can you not make the simplifying assumption that x is small?

Given the following sequence: LHYEAIAKAWNDAF

a. Classify each amino acid into polar, non-polar, & charged (at pH 7.0)–put a letter above each to show if polar (p), non-polar (n), or charged (c).

b.What are the ionizable groups?

c.What is the order of the pKaʼs going from low to high pH

d.What is the isoelectric point (pl) of this peptide?

e.At the pHʼs of 3, 6, & 9, what is the charge state?

f.What type of secondary structure would this peptide take and why?

g.How long would it be?

h.How many hydrogen bonds, at maximum

Hello,

In an experiment to determine the concentration of glucose in a sample, we are supposed to make a glucose assay with glucose solutions of known concentration. The absorbance for each solution of known concentration will be plotted, so that we can use the line of absorbance rates to later find the concentration of our unknown sample. We need to make our own dilutions for the assay.

We are given a stock glucose solution of 10mg/mL (1000mg/dL). My group wants to make solutions with concentrations 0mg/dL; 100mg/dL; 200mg/dL; 300mg/dL; 400mg/dL; and 500mg/dL. We are unsure of the best way to make the dilutions.

Would we make a 100mg/dL dilution be adding 1 part of stock and 9 parts deionized water? And a 200mg/dL dilution by adding 2 part stock and 8 parts deionized water; 300mg/dL as 3 parts stock and 7 parts deionized water, and so on? I'm unsure of how to do this.

Thank you!

If 500 mg of Fe³⁺ and 50 mg of OH^- are added to 1L of pure water, what will be the final equilibrium concentration of Fe³⁺ and OH^-. Assume water does not dissociate.

Fe(OH)₃ => Fe³⁺+3OH^-, pKs =38.57, MW_Fe = 55.85 g/mol, MW_OH = 17.01 g/mol

A student creates 150ml of a buffer that is .018M in formic acid and .016M in sodium formate. What would the pH of the buffer be after the addition 15ml of .070M HCl solution to the buffer?

a) 3.69

b) 3.85

c) 4.18

d) 1.15

e) 3.30

Give the hexapeptide sequence that gives the following fragments on limited acid hydrolysis:

Use the single letter abbreviations for amino acids.

Fragment 1: Pro-Leu-Gly
Fragment 2: Arg-Pro
Fragment 3: Gly-Ile-Val

Hexapeptide:

Aspirin is produced by the reaction of salicylic acid (C7H6O3 . M = 138.1 g/mol) and acetic anhydride(C4H6O3, M = 102.1 g/mol).

                  C7H6O3(s) + C4H6O3(l) → C9H8O4(s) + C2H4O2(l)

If 2.04 g of C9H8O4 (M = 180.2 g/mol) is produced from the reaction of 3.00 g C7H6O3 and 5.40 g C4H6O3, what is the percent yield?

Carbon monoxide at 25C and saturated steam at 150C are fed to a continuous water-shift reactor. The product gas, which contains 40.0 mole% H2, 40.0 mole% CO2 and the rest H2O(v) emerges at 500C at a rate of 3.5 SCMH, and goes to a condensor, where all of the H2O is condensed. The gas and liquid streams leaving the condensor are at equilibrium at 15C and 1 atm. The liquid leaving the condensor can be assumed to be pure water (no dissolved gases).

a) Calculate the % excess steam fed to the reactor and rate of condensation of the water (kg/h).

b) Calculate the rate (kW) at which heat must be removed from the condensor.

c) Taking atomic species at 25C as references, prepare and fill in an inlet-outlet enthaply table and calculate the required heat rate of heat transfer (kW) to or from the reactor.

A student ran two separate substitution reactions, Reaction A and Reaction B, in lab that utilized an alkyl halide and a nucleophile. However, he did not know if the reactions proceeded through an S_N1 or S_N2 mechanism. To determine the mechanism for both reactions, the student increased the concentration of the nucleophile in Reactions A and B. The rate of reaction for Reaction A increased. The rate of reaction for Reaction B remained the same.

(a) Which reaction is the S_N1 reaction? (1 pt)

(b) Which reaction is the S_N2 reaction? (1 pt)

(c) Explain both of your choices. (4 pts)

Solve an equilibrium problem (using an ICE table) to calculate the pH of each of the following solutions.

a) 0.13 mol*L−1 CH3NH2

b) 0.13 mol*L−1 CH3NH3Cl

c)a mixture that is 0.13 molL−1 in CH3NH2
and 0.13 molL−1 in CH3NH3Cl