Chapter 1.6, Problem 13PTS

1) Draw the structures of D-lysine and L-lysine and assign R/S configuration (showing your workings). 2) Draw the predominant ionisation forms of the free amino acid lysine, at pH 1.0, 8.0, and 11.0. pKa values: 2.2 (-COOH), 9.0 (α-NH3+), 10.5 (side-chain). 3) Calculate (showing your workings) the % of the different ionized species that are present in a 1.00 M solution of L-proline at pH = 10.0. pKa values: 1.95 (- COOH), 10.64 (α-NH3*). 4) a) Draw the tripeptide Tyr-Pro-Lys once with a trans peptide bond between Tyr and Pro and once with a cis peptide bond between Tyr and Pro. b) The electrospray ionization mass spectrum (ESI-MS) of the tripeptide you designed in part (a) shows peaks indicative of mono-protonation and di- protonation of the tripeptide. At what values of m/z would these peaks be expected (no fragmentation)? Briefly explain your answer (showing your workings). 5) How could the sequence of Ala-Met-Thr be distinguished from that of Thr-Ala- Met by tandem ESI-MS-MS?…

LABORATORY REPORT FORM Part I. Determination of the Formula of a Known Hydrate 1. Mass of empty evaporating dish 3. Mass of hydrate Using subtraction or mass by difference, find the mass of the hydrate 76.96 -75.40 75.40g 76.968 1.568 01.56 76.90 g 2. Mass of evaporating dish + hydrate 4. Mass of evaporating dish + hydrate (after heating) First 76.98 g Third 76.66g Second Fourth (if necessary) 76.60g 5. Mass of anhydrate 6. Mass of water lost by the hydrate 7. Percent of water of hydration (Show Calculations) 8. Moles of water (Show Calculations) mol mass of water = MM of water (g/m) 9. Moles of anhydrate (Show Calculations) 10. Ratio of moles of water to moles of anhydrate 11 F(Show Calculations) 11. Formula of hydrate - Mass of water (g) x 100 % water hydration g g % Mass of hydrate (9) x IC % = (Mass of hydrate- mass of an) mass of hydrate (g) % = (1.569- × 100= mol 1.569 mol Mol Mass of anhydrate/MM of anhydrate 12. What was the color of the hydrate? blue What was the color of the…

compared t-critical with t-calculated and 95% confidence interval to answer this question

Comparing two means. Horvat and co-workers used atomic absorption spectroscopy to determine the concentration of Hg in coal fly ash. Of particular interest to the authors was developing an appropriate procedure for digesting samples and releasing the Hg for analysis. As part of their study they tested several reagents for digesting samples. Their results using HNO3 and using a 1+3 mixture of HNO3 and HCl are shown here. All concentrations are given as ppb Hg sample.   HNO3: 161, 165, 160, 167, 166 1+3 HNO3–HCl: 159, 145, 140, 147, 143, 156   Determine whether there is a significant difference between these methods at the 95% confidence interval.

Comparison of experimental data to “known” value. Monna and co-workers used radioactive isotopes to date sediments from lakes and estuaries.21 To verify this method they analyzed a 208Po standard known to have an activity of 77.5 decays/min, obtaining the following results.   77.09, 75.37, 72.42, 76.84, 77.84, 76.69, 78.03, 74.96, 77.54, 76.09, 81.12, 75.75   Do the results differ from the expected results at the 95% confidence interval?

Explain the difference between the propagated uncertainty and the standard deviation. Which number would you use to describe the uncertainty in the measurement? if the standard deviation is 0.01 and the propagated uncertainty is 0.03

Propagation of uncertainty. Find the absolute and percent relative uncertainty assuming the ±-values are random error. 7.65±0.04 + 5.28±0.02 – 1.12±0.01 85.6±0.9 × 50.2±0.7 ÷ 13.8±0.5 [4.88±0.07 + 3.22±0.05] / 1.53±0.02

Explain the difference between the propagated uncertainty and the standard deviation. Which number would you use to describe the uncertainty in the measurement?

Circle the compound in each pair where the indicated bond vibrates at higher frequency. WHY IS THIS? Provide thorough explanation to tie topic.