Food Dyes Analysis of Commercial Products

Carbon monoxide is another common poison found in the forensic laboratory. Explain how UV-visible spectrophotometry is applied to quantify carbon monoxide in blood samples.

Calculate the molar extinction coefficient (e) of a molecule at a particular wavelength given that a 0.000764 M solution of the molecule produced a fluorescence intensity (I) of 1177 when the irradiance of the beam incident to the sample (Po) was 821 and the length of the medium (b) was 1.12 cm. The proportionality constant k' for this molecule is 0.319. € = ×10 TOOLS M-1.cm-1

Please explain the answer. Plotting the ratio of atomic emission of Pb to the atomic emission of yttrium (internal standard) vs the concentration of Pb in contaminated water, the linear regression equation from 10-point calibration was found to be y=0.114x-1.8872. What would be the average concentration of Pb in contaminated water if three aliquot of a sample of 10 folds' diluted solution of contaminated water provided the ratio of emission of Pb to that of yttrium as: 3.92, 3.86, and 3.87? а. 3.89 ppb b. 38.9 ppb с. 357 ppb d. 35.7 ppb

The luminescent first-order decay of a certain organic molecule yields the following data t/s 1 2 4 10 I 100 60.65 36.79 22.31 13.53 8.21 0.67 where I is the relative intensity. Calculate the mean lifetime t for the process. 1.59 X S Is it fluorescence or phosphorescence? O fluorescence

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Given C6H12O2 chemical formula. chemical shift , intergration, multiplicity and interpretation needed.

Flame Atomic Absorption Spectroscopy (FAAS) method is selected due to its wide applicability for metal ion analysis in drinking water samples. Provide appropriate discussion to determine the concentration of selected heavy metals (Cu and Cr) in the unknown tap water sample.

Suppose the difference in rest energy of the neutron and proton were Qn = (mn − mp)c2 = x MeV instead of Qn = 1.29MeV, with all other physical parameters unchanged. Estimate Ymax, the maximum possible mass fraction in 4He, assuming that all available neutrons are incorporated into 4He nuclei. Hint: Compare the new rest energy of the neutron to the electron and consider how that would impact the decay of neutrons.  Will free neutrons decay at all in this scenario?  If the neutron decay is negligible, then the ratio of protons to neutrons to protons will remain the same as it was at the time of freeze-out (for a given Qn).   Value: x=0.158 MeV

using the following information to construct a valid hypothesis addressing the effect of pH and temperature on the hydrolysis of starch.   Per bench, prepare the stock amylase enzyme solution by adding distilled water to the powdered enzyme in the flask , each bench will share one flaks of enzyme solution. per groups, turn on the spectrometer and set the wavelength to 560nm.allow the instruments to warm up for at least 10 minutes. per group, set up 17 cuvettes in a Styrofoam rack. Add 3 drops of iodine (IKI) to each coveter. per group, prepare the “black” cuvette by rapidly adding 3 mL of maltose standard solution to one of The prepared cuvettes containing IKI. Rapid addition of the maltose will mix the maltose and IKI

What is the purpose of a calibration curve in analytical chemistry?

A company is producing a powder which can be reconstituted as a healthy drink for the elderly. Analysis of the powder for calcium involved using the following procedure. 4 g of powder was reconstituted to 150 ml with water. Thirty ml of 24 % TCA was added to 30 ml of this solution. The mixture was allowed to stand for 15 mins and then filtered. The filtrate was analysed for calcium using atomic absorption spectroscopy. From the standard curve it was found that the reading for the analysed sample was 24mg/litre. Calculate the concentration of calcium in the powder (mg/kg).

Instrumentation of IR spectroscopy?  Please answer at your own words.

The space immediately surrounding stars, the circumstellar space, is significantly warmer because stars are very intense black-body emitters with temperatures of several thousand kelvin. Discuss how such factors as cloud temperature, particle density, and particle velocity may affect the rotational spectrum of CO in an interstellar cloud. What new features in the spectrum of CO can be observed in gas ejected from and still near a star with temperatures of about 1000 K, relative to gas in a cloud with temperature of about 10 K? Explain how these features may be used to distinguish between circumstellar and interstellar material on the basis of the rotational spectrum of CO.

For a molecule, the phosphorescence lifetime without quenching is 1.0 s while with a quencher population of 10-2 M the phosphorescence lifetime is 0.10 s. Calculate the rate constant for phosphorescence assuming that kisc >> (kF + kec + kic). Calculate the rate constant for external conversion of the triplet state (kec’), the quenching rate constant for the triplet state (kq’), and the Stern-Volmer quenching constant. Assume that intersystem crossing from T1 to So is negligible.

Chemistry   0.1237 (±0.0001) g of sodium carbonate (Na2CO3) required 22.46 (±0.02) cm3 of aqueous HCl for complete neutralisation. Determine the concentration of the HCl in mol dm–3 together with its uncertainty in mol dm–3 to an appropriate number of digits. You may assume the error in the molar mass of Na2CO3 is negligible.

The IR spectrum of 2-methyl-1-butanol (H;CCH,CH(CH;) CH,OH) and tert-butyl methyl ether [(CH;);COCH3] are shown below. Assign cach spectrum to the correct com- pound and identify the frequencies and the functional groups used to support your assignment. λ (μm) 6 7 8 9 10 11 12 1314 15 2.5 100 3 5 90 80 70 60 50 40 30 20 10 4000 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400 Frequency (cm-1) A (µm) 7 8 9 10 11 12 13 14 15 2.5 100 3 5 20 4 6 90 80 70 60 50 40 30 20 10 4000 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400 Frequency (cm¬!) (%) Transmission (%) Transmission 20

An atomic absorption method for the determination of the amount of iron present in used jet engine oil was found from pooling 30 triplicate analyses to have a standard deviation s = 3.6 mg Fe/mL. If s is a good estimate of σ, calculate the 95 and 99% confidence intervals for the result 18.5 mg Fe/mL if it was based on (a) a single analysis, (b) the mean of two analyses, and (c) the mean of four analyses.

(c) Comment on the truth, or otherwise, of the following statement. "Fast time-scale flash photolysis can be used to determine rate constants for collisional relaxation (quenching) processes of singlet and triplet states. Radiative decay rate constants (Einstein A coefficients) can be determined from such measurements, and can also be calculated from absorption coefficients."

A kinetic experiment is carried out in a flow tube where the flow rate is 25 m s¯¹. The detector is a spectrophotometer, and absorbances are measured at various distances along the tube. The reactant has a molar absorption coefficient of 1180 mol-¹dm³ cm¹ at 420 nm. The absorbances are measured using a 1 cm optical cell. Use this information, and that in the following table, to calculate [reactant] as a function of time. Then plot a graph of [reactant] versus time and comment on its shape. May plot using excel. distance cm A 2.0 0.575 4.0 0.457 6.0 0.346 8.0 0.232 10.0 0.114

CPU/RAM ProctorU e Proctor e Proctoru o.com/collab/ui/session/join/43918c0bf9cb421ca7b98b0075f5f239 Firefox Ex SPECTROSCOPY 1. If the concentration of solute in a solution is high, the Absorbance will be high or low and why? 2. Was the spectroscopy experiment qualitative or quantitative analysis? 3. If we have 12M HCI and we need 3 L of 1M HCI, how much 12 M should we use? 4. What does Molarity mean? 5. When must safety goggles be worn? 6. If you make a mistake recording data, what must you do? spec hw.pptx (2/3) ..% An

The Na* concentration in a blood serum sample was determined using the method of standard addition and atomic spectroscopy. 25.00 mL aliquots of serum were pipetted into five 50.00 mL volumetric flasks into which 2.640 M NaCl standard was added as shown in the table below. After dilution to volume, the emission of each solution was measured and used to plot a calibration graph. Flask 1 23 4 5 Vol. of standard (mL) 0 1.00 2.00 3.00 4.00 Emission signal 3.13 5.40 7.89 10.30 12.48 Analytical signal (emission) 14 42 10 12 4 2 0 0 0.05 y = 44.697x + 3.12 R² = 0.9995 0.1 0.15 Concentration of added analyte (M) 0.2 a) Using the plotted calibration graph, calculate the Na* concentration in the blood serum sample. b) Provide a possible reason why the serum sample might have been analysed using this analytical procedure. 0.25

17. Advection is represented in the advection-dispersion equation by the term +v Əc/ax +KC -v ac/ax -μС

Infrared Spectroscopy (IR) is very useful for determining the functional groups present in an organic molecule. For each of the spectra below, complete the following: • Build the molecule in Spartan and describe the motion of the molecule at each key absorption frequency • Identify key absorption frequencies in the spectrum and identify the type of stretch/bend/wag/etc. (i.e. O-H) • Match the spectra from the provided structures • Identify the main functional groups in the molecule OH A OH H B E F H N NH2