Techniques ICA (1)

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Louisiana State University *

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1208

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Biology

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Jun 5, 2024

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docx

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BIOL 1208 Summer 2024 Techniques In-Class Assignment Name: Gabrielle Deese Lab Partner Name(s): Amiyah, Dallis Remember : Although you work with partners for lab experiments, written assignments must be completed independently and answered in your own words . All text must be able to be processed in Turnitin, so do not use pictures, screenshots etc. See the syllabus for more information. EXERCISE I: PIPETTES AND PIPETTING 1. Serological Pipettes Exercise check off: Lab Partner Initials: AJ, DD 2. Micropipette Exercise (card) check off: Lab Partner Initials: AJ, DD 3. What is the range limit of the following pipettes? P100 micropipette: 10-100 microliters P1000 micropipette: 100-1000 microliters 4. What are the purposes of the first and second stops of a micropipette? First: load Second: dispense Using the appropriate micropipette, dispense 160 µL of water onto the scale. Follow the scale directions at your bench to Tare/Zero scale before dispensing water into weigh boat. (Questions 5 and 6) 5. List micropipette (P100 or P1000) selected: p1000 6. Scale readout of volume in grams : 0.16 grams of water 7. A lab technician dispenses liquid onto a scale and the readout volume is 0.56 grams. How many microliters was their pipette set to? 156 ul of water EXERCISE II: SPECTROMETRY 8. If an object is blue, which colors are being absorbed (ROYGBV)? Transmitted? Absorbed: ROYGV Transmitted: Blue 9. What is directly measured by a spectrometer? Concentration 10. What is the purpose of a blank in spectrometry? To make a horizontal line on the spec to be able to measure the specific light 11. What are the units for absorbance? For concentration? Absorbance: ODU Concentration: M A. COBALT CHLORIDE 12. Based only on your observation of the colors of the solutions, which cobalt chloride (CoCl 2 ) sample was more concentrated (A or B)? How do you know? 1
BIOL 1208 Summer 2024 the more concentrated sample was A because it is a darker pink color compared to sample B. 13. Provide the absorbance values from the spectrometer reading for both solutions. Use the graph to visually estimate the concentration . Use the standard curve equation to calculate the concentration (Remember, solve for X !). Show your work for at least one calculation ! CoCl 2 Solution A : o Absorbance (ODU): 0.872 ODU o Estimated Concentration (M): 0.17 M o Calculated Concentration (M): 0.17 M CoCl 2 Solution B : o Absorbance (ODU): 0.412 ODU o Estimated concentration (M): 0.08 M o Calculated Concentration (M): 0.081 M B. CRYSTAL VIOLET FADING OVER TIME 14. How do you expect the color intensity of crystal violet to change over time when combined with sodium hydroxide (NaOH)? Based on Beer’s law, what do you predict will happen with the absorbance values of this solution over time? It will turn colorless. I think that if we left the mixture overnight it would be clear by the next day. 15. Complete Table 1-4; be sure to include a complete caption (include the standard curve equation). Show your work for at least one calculation. Table 1-4. Absorbance and concentration of the crystal violet and sodium hydroxide solution over time Time (s) Absorbance (ODU) Concentration (mM) Estimated Calculated 0 0.201 ODU 0.022 mM 0.021 mM 30 0.213 ODU 0.023 mM 0.023mM 60 0.200 ODU 0.020m M 0.022mM 90 0.198 ODU 0.018 mM 0.021mM 16. Does your data in Table 1-4 support your predictions (color intensity and absorbance) from #14? Explain. Yes, I was told we only had to upload one part of evidence for this assignment, so I uploaded evidence for this assignment. This evidence shows how to find the estimated and the calculated concentrations. 2
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