Lab_04_Spectrophotometry

Why is the blank solution needed in spectrophotometry?  A. A blank solution is used to clean the spectrophotometer b. A blank solution is used to calibrate the spectrophotometer readings: they document the baseline response of the environment- instrument- sample system

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

1. Give the general steps in the use of a spectrophotometer. 2. Define the following: a. ) Optical Density b.) Transmittance c.) Beer's Law

What technique(s) in spectrophotometry would use to determine the identity of matter? A. Qualitative  b. Quantative  c. Any technique is useful

Label the graph with the correct axes for a standard curve used in a spectrophotometry experiment. y X Answer Bank Concentration (M) % Transmittance Sample # Absorbance Density (g/L)

Which of the the following is false regarding spectrophotometry? A. The concentration of a sample increases with path length of the curvette or sample holder since the absorbance increases B. when absorbance increases, transmittance decreases C.The absorbance coefficient depend on wavelength of light and type of sample.

why does the choice and use of a blank matter for Spectrophotometry?

" Spectrophotometric analysis" refers to methods that are based on light absorbance. O True False

Does sunlight affect uv vis spectrophotometer ? is this statement true? ''Sunlight can dim the measurements by heating the instrument, leading to inaccurate measurements.''

Question 9 The basic spectrophotometer is composed of four components. Which component listed below is NOT one of the four? beam splitter monochromator detector O light source

why is water used as a blank for Spectrophotometry?

Choose the most accurate descriptions about quantitative analysis using atomic absorption spectrophotometer (AAS). A. The sample was digested with a concentrated acid, the digested solutions were diluted in 10x dilution factor and then was directly injected into AAS. B. AAS instrument can detect elements present only in solid samples C. Desolvation, vaporization, combustion, atomization, and ionization are the processes involved during sample analysis. D. Hollow cathode lamps (HCL) are energy sources that a cathode is made from a platinum element in a glass envelope of an inert filler gas. AAS is the most widely used instrumentation for the analysis of metal and traces metal samples. State one factor from the following is insignificant to AAS. A. Wide range sample analysis B. Effective C. Low cost D. Robust

B.  Quantitative Spectroscopy   Prepare two graphs, %T vs. Concentration and Absorbance vs. Concentration, using the data for the cobalt standards.  The concentrations of Cobalt standards 2-4 can be calculated using simple dilution calculations. Concentration should be on the x-axis for each of these graphs.  The first should clearly show some curvature while the second should be a linear curve. Using the absorbance graph you can determine the concentration of the unknown. Take the absorbance value for the unknown and find that value on the y-axis.  Draw a horizontal line from that point on the y-axis to the plotted line.  From the point where the horizontal line intersects the plotted line, draw a vertical line straight down to the x-axis.  Record the value from the point where you hit the x-axis as the unknown concentration.

Using the lab instructions and data table with data, please help me complete part 1 and 2 of my lab worksheet

If 50.0 ml of water is added to 50.0 ml of a blue dye solution, and the newly diluted silution is placed in the spectrophotometer, what do you think would happen to the absorbance? choose all that apply! a. there would be no change  b. it would increase c. there is not enough information to answer the question d. it would decrease

One disadvantage of thin layer chromatography is that... it cannot be used for quantitative measurements. O it consumes large volumes of solvents O it cannot analyze volatile samples it cannot be used to analyze many samples simultaneously it requires a large amount of sample for analysis

what is the difference of spectrophotometer with ATR (attenuated total reflectance) and one without it. What are the advantages of one over the other?

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 concentration of Cu in analyzed solution (mg/L) for each trial?