Spring 2024 CHEM 120-Spectrophotometry

We are stuck on 9.  We get how Q is 16 and rxn goes left.   at eq 2+ x.    2 + x.    -2 x We get x= 1.    Therefore  k = 4.  Please help us.   Questin 9.  See conditions from 8 This is not a graded question as it is a practice question . I am 60 years old and helping my son prepare for the AP exam in a few months. We do questions at the back of the textbook by Zumdahl and Zumdahl

The spectroscopic data in the table is generated with five solutions of known concentration. Concentration (M) 0.0133 m= 0.0266 0.0532 0.106 0.213 Absorbance 0.1271 What is the intercept of the linear regression line? 0.08531 0.5388 1.069 Use a spreadsheet program, such as Microsoft Excel, to graph the data points and determine the equation of the best-fit line. 1.954 What is the slope of the linear regression line formed by these points? M-1

Pre-Lab Questions- To be completed BEFORE lab as an entry slip. These questions are based on content presented in the lab procedure and in lecture. 1. Consider the electromagnetic spectrum. (Reference Site) -- Increasing Frequency (v) 10² 10% 10 10² 10% Trays 1044 10 10- 10 UV 30* 10 IR Visible spectrum 10² 10* 30 Microwave FM AM Radio waves 10° 10² 10 H 10² Increasing Wavelength (2)→ 10 Increasing Wavelength in m a. What type of radiation has the longest wavelength? 10 10² 10 voto b. What type of radiation has the highest energy? Long radio waves c. Looking at the emission line spectrum for hydrogen in Figure 1. Which colored line corresponds to the emission of the highest-energy photon?

The students conducted the assay for LDH activity using the two serum samples. Each cuvette (path length 1 cm) contained 3ml of a suitable assay buffer (including pyruvate as substrate). 20 microlitres of either serum was added to the cuvette and the absorbance values immediately recorded at the optimum wavelength for a period of 5 minutes (absorbance readings taken every 30 seconds).   Protein concentration of serum sample (mg/ml) Change in absorbance at optimum wavelength per minute Control serum (C) 8 -0.04 Diseased serum (D) 7.8 -0.6 1c. Using the molar absorption coefficient of NADH as 6220 M-1 cm-1, and by application of the Beer-Lambert law, estimate the enzyme activity in the two samples (C and D). Express activity as moles per second.  1d. Estimate the specific activity of the two samples (moles per second per microgram).

10. The concentration of haemoglobin in a blood sample was determined by spectrophotometry. A standard curve of the absorbance at 412 nm of several solutions of known haemoglobin concentrations was created. The data for the standard curve is shown below. a. Calculate the linearity coefficient (r), y-intercept and slope. b. What is the concentration (in ug/mL) of haemoglobin in your sample if the absorbance obtained at 412 nm was 0.303? Absorbance Concentration of standard solution (pg/ml) (412nm) 0.069 1 0.113 2 0.201 4 0.377 8. 0.730 16

To determine the amount of copper and the identity of the copper compound in the unknown sample, a 100-mL solution containing 120.8 mg of the sample was initially prepared. Then, 5.00 mL of this solution was pipetted and diluted with deionized water in another 100-mL volumetric flask. The absorbance of this diluted solution was determined three times at the analytical wavelength. The data is in the table below.    Unknown sample Trial 1 Trial 2 Trial 3 Absorbance (AU) 0.378 0.379 0.377 What is the corrected absorbance?

To determine the amount of copper and the identity of the copper compound in the unknown sample, a 100-mL solution containing 120.8 mg of the sample was initially prepared. Then, 5.00 mL of this solution was pipetted and diluted with deionized water in another 100-mL volumetric flask. The absorbance of this diluted solution was determined three times at the analytical wavelength. The data is in the table below.  Unknown sample Trial 1 Trial 2 Trial 3 Absorbance (AU) 0.388 0.389 0.388 What is the Corrected Absorbance of each trial? How do you get the corrected absorbance?

To determine the amount of copper and the identity of the copper compound in the unknown sample, a 100-mL solution containing 120.8 mg of the sample was initially prepared. Then, 5.00 mL of this solution was pipetted and diluted with deionized water in another 100-mL volumetric flask. The absorbance of this diluted solution was determined three times at the analytical wavelength. The data is in the table below.  Unknown sample Trial 1 Trial 2 Trial 3 Absorbance (AU) 0.375 0.374 0.376   What is the concentrartion of Cu in the analyzed solution?

To determine the amount of copper and the identity of the copper compound in the unknown sample, a 100-mL solution containing 120.8 mg of the sample was initially prepared. Then, 5.00 mL of this solution was pipetted and diluted with deionized water in another 100-mL volumetric flask. The absorbance of this diluted solution was determined three times at the analytical wavelength. The data is in the table below.    Unknown sample Trial 1 Trial 2 Trial 3 Absorbance (AU) 0.388 0.389 0.388 What is the concentration of Cu in analyzed solution (mg/L) for each trial?

O Homework in Chem101 - due Su X My Questions | bartleby ( Periodic Table – Royal Society of how to take a screenshot on an + A learn.maricopa.edu/courses/1132256/modules/items/19018052 CHM151 17003 > Modules > Weeks 8 & 9 - Chapter 7 > Homework in Chem101 - due Sunday night CG 2020 FALL CRED Question 37 of 4 Submit Account Home Complete the balanced neutralization equation for the reaction below: Announcements Dashboa |Modules HCIO-(aq) + CSОН(ag) — rd Concourse Syllabus Courses Grades D2+ N3+ D4+ Cisco Webex Groups 1 2 3 4 7 8 9. Tutoring/Learning Center Calendar Os Do Inbox (s) (1) (g) (aq) History Cs H CI Help • Previous Next » Library 1:03 PM O Type here to search 10/18/2020 +

A student weighed out 0.150 g of protein powder and dissolved it in 100 mL of water (Solution 1). The student then diluted this solution by transferring 1 mL into a 25 mL flask and diluting with water (Solution 2). Finally, 1 mL of that solution was transferred to a test tube and combined with 4 mL Bradford reagent. The absorbance of the solution in the test tube was 0.187. Assuming that the best fit linear line of the standard curve was y = 0.04144 x + 0.01521 (μ g mL), calculate the percent protein by mass in the original protein powder.

Here is the protocol for a UV-Vis spectrophotometer to detect water and chlorine-carbon. 1.Dissolve the water and chlorine-carbon compounds in a solvent, such as water. 2.Prepare a standard solution of known concentration that is similar to the sample being measured. 3.Calibrate the spectrophotometer using the standard solution. 4.Measure the absorbance of the sample using the spectrophotometer. 5.Calculate the concentration of the compounds in the sample using the calibration curve obtained from the standard solution. How is the spectrophotometer calibrated with standard solutions? When is the blank solution placed in the spectrophotmeter?

QUESTION 4 4. The main difference between "in-time" and "in-space" spectrophotometer design is that the former uses timed mirrors to alternate measurements between reference and sample using the same detector, while in-space uses a beamsplitter to send light through a different path to the same detector which is able to retrieve the signal using lock- in amplification. A. False B. True

The data in the table are used to create a calibration curve for the determination of RNA from its absorbance at 260 nm. Use a spreadsheet and the least-squares method to determine the slope and y-intercept of the best straight line fit to the calibration curve. Do not subtract the blank reading when creating the calibration curve. m= RNA (µg) 0.00 10.29 20.58 30.87 41.16 mass= Absorbance at 260 nm 0.227 0.452 0.786 1.078 1.296 Hg-1 Using the slope and intercept of the calibration curve, determine the quantity of RNA in a sample that gives an absorbance of 0.523. µg

The spectrophotometer is set at 600 nm. The absorbance of each cuvette is read. The data is shown below: Cuvette 1 is the clank Cuvette # ml albumin Absorbance 0. 0.2 .063 3 0.4 .163 4. 0.6 .187 0.8 .253 1.0 .289 Using this data, plot an Excel graph showing absorbance (y-axis) vs ml albumin (x-axis). Find the correlation coefficient (r). R2 > 0.99 = excellent data; r2 0.98-0.95 good data r2 0.94 -0.90 = fair data. How would you describe this data?- To find the relative sensitivity, for each of tubes 2-6 (neglect blank), perform the following operation absorbance (Lowry)/Absorbance (Biuret x 0.5 gram albumin (Biuret)/0.05 gram (Lowry) x 200 ml (Lowry)/100 mL (Biuret). This implifies to Relative sensitivity = 20 dilution factor x absorbance (Lowry)/Absorbance (Biuret). Report your relative sensitivity as an average of all 5 values.

Plot a professional quality standard curve (absorbance vs. protein amount in µg) with an appropriate title and caption underneath the plot from the data give above. The caption should include the best-fit data.

Enter this data set in Excel, construct an appropriate plot, develop a trendline (not forcing the trendline through 0,0), and determine a linear equation. If an unknown sample exhibits an absorbance of 0.517, determine the concentration of the compound in this sample. mM A 0 0 0.48 0.21076 0.96 0.4004 1.44 0.6072 1.92 0.7546 2.4 0.9086 O 1.00 mM O 1.10 mM O 1.20 mM O 1.40 mM O 1.30 mM

Table 1. pH of water samples Sample No. Water Samples pH 1 Tap water from household 6.59 2 Water from creek 7.35 3 Water from river 7.35 4 Unknown sample 7.00 Table 2. Absorbance of Samples Table 3. Calibration Curve Data* Sample No. Absorbance Absorbance 3- Concentration of PO4 Ions, ppm (1 pt each) 1 1.33 1.0 0.050 2 3.26 2.0 0.093 0.89 3.0 0.137 4 0.099 4.0 0.185 5.0 0.230 *Provided by the instructor II. Graph Determination of Phosphate Concentration 3- 1. Using Excel, plot the concentration of PO4* (x-axis) vs. absorbance (refer to Table 3) The olot must show the equation of the best-fit (or trend) line of the graph. Attach the graph below

Table 1.0 of data showing calibration standards prepared by dilution and the absorbance Concentration CuSO4 (M) Volume of 0.5M (ml) Volume of D/Water (ml) Absorbance 0.00 0.10 0.20 0.30 0.40 0.50 II. 0.00 1.00 2.00 3.00 4.00 5.00 5.00 4.00 3.00 2.00 1.00 0.00 1. Construct a graph of concentration against absorbance, clearly show a best fit line. Find regression of your graph. Show how 0.000 0.406 0.638 0.854 1.202 1.276

Using the data below, please create a calibration graph and determine the concentration of the unknown sample. Standard #1 Standard #2 Standard #3 Unknown sample Concentration 1.5 x 10 M 2.0 x 103 M 2.5 x 10 M ? Absorbance 0.61 0.80 0.98 0.72 a) 1.6 x 10 M b) 1.8 x 10° M c) 2.1 x 103M d) 2.2 x 10 M

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If Johnny Joestar measured the amount of light absorbed by the analyte in a sample to determine its concentration, what kind of method did he use?   Volumetric method   Gravimetric method   Electroanalytical method   Spectroscopic method

List three typical examples applications of SFC analysis.

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The concentration of hydronium ions and hydroxide ions can vary widely in a solution, easily from 1 M to 1 x 10-14 M. This variation is too wide to fit on an analog readout. In order to make this into a smaller scale suitable for an analog readout, the log to the base 10 was used so that the read out is focused on powers of 10. Note that the log [1] = 0, and the log of 1 x 10-14 = -14. It was then decided that the numbers should be positive so the sign was changed. The way to measure concentrations of both H+ and OH- was thus defined as -log. This was then referred to as p. Thus, pH = -log[H+], pOH = -log[OH-], and pK = -log[Keq]. You need to figure out how to do this mathematical manipulation on your calculator. The acid-base reaction in pure water is H2O + H2O ⇔ H3O+1 + OH-1 and it was found that in pure water under standard conditions the [H3O+1] = [OH-1] = 1 x 10-7 M Neutral pH is defined as having a [H+] or [H3O+1] of 1 x 10-7 M. The pH of a neutral solution is thus pH = -log[1 x…

Plot (using appropriate scaling, with titles, axis labels, and units where applicable) the absorbance versus the concentration of each standard on graph paper. The slope of the best- fit line will be , in A = ,bc (Beer’s Law, where A is absorbance, , the extinction coefficient, b the path length, and c the concentration of the sample). Produce and submit the standard curve

■ True or False: in a TOF analyzer, a fragment of low mass reaches the detector first ▪ In GCMS when we know what analytes we are measuring we use not know what analytes are in the sample we use than scan. ▪ A) Scan; SIM ■ B)SIM; scan • C) SIM; SIM mode. When we do mode. SIM allows greater sensitivity

Wavelength (nm) a. Which part of the visible light spectrum is most useful (most absorbed) by chlorophyll b? b. Which pigment do you think was best at absorbing the red light that was shown on the leaves when using a red-light filter in the experiment? Explain. c. Do you think a greenhouse with green and yellow lights would be very successful in terms of plant growth? Explain. 100% n(US) home end insert prt sc F10 F12 DII F6 FB F9 F11 F7 F3 F4 F5 & %23 2$ 4. 5 7 8. Y U F G H

Document1 - Word Search (Alt+Q) References Mailings Review View Help Write the corresponding letters to the following descriptions. Each proposal can be associated with 0 or 1 match and each letter is not necessarily associated with a proposal. a. [Ar] 4s? b. 1s 2s2p63s23p3 c. 1s2s2p2 d. [Ne] 3s23ps e. [Ar] 4s23d10 f. 1s22s! g. None of those answers 1. I am a halogen 2. I am a transition metal 3. I am alkaline 4. I have exactly 2 single electrons 5. I am the smallest of the atoms presented here 6. I have exactly 3 valence electrons 7.I am the most paramagnetic of the atoms presented here 8. I am the copper 9.I am isoelectronic with Ti2+ IF cessibility: Good to go IA 16 SIS

Plot a calibration graph of absorbance vs concentration of Ca2+ and determine the concentration of Ca2+ in the unknown tap and unknown bottle water samples.

Page of 5 O + 3 ZOOM Question 1: Using a well-known protein estimation technique, absorbance reading for a set of standards were obtained. You were required to plot the data. Which graph would you use? Plot the data using the graph type. Protein Absorbance concentration (mg/mL) (a.u.) 0.01 0.05 0.12 5 10 25 0.25 0.63 1.25 50 Question 2: Enzymes are biological catalysts and perform important biochemical reactions in the body. A group of scientists discovered a new enzyme – Enzyme X. To understand the working of this enzyme, they performed biochemical assays to assess the activity of the enzyme. The results for which are shown in the table below. Based on the information provided in the table, please state which graph would you use? Plot the data using the graph type. Enzyme activity (%) 35 55 pH 3 4 5 68 6 79 7 98 85 20 8 9 10

chem 132 Exam 1 2022 • Saved - Search (All+Q) hmdoyle107@gmail.com H Draw Design Layout References Mailings Review View Help Table Design Layout PFind - 12 - A A Aa v A Arial No Spacing Heading 1 & Replace Normal Dictate Sensity Editor R BIU- a x, x A 2. A E= = = E- 2 - H- > Select Paragraph Styles Editing Voice Sensitivity Editor Font Reum 23. Which of the following compounds contain a hemiacetal functional group? OCH3 OH но. OCH3 A OCH3 В OCH3 C a. A and B b. B and C c. B only d. C only 24. Which of the following compounds contains an acetal functional group? OCH3 -OCH3 -OH OCH3 A B a. A and B c. B and C b. A and C d. C only ards OFocus Text Predictions: On Accessibility. Investigate prt sc home end F12 delete insert F3 F8 F4 ES F6 F10 F11 FI & 2 3 4. 6 7 8 9 Q W E R T Y U A S | D G H K C V |N M alt alt ctrl