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10 Nov 2019

Please explain your answer to the following questions. Sincethere are 4, I have increased the points. Thank you verymuch.

The following calibration data were collected by measuring the absorbance of each solution five times, and then calculation the average absorbance for each solution. The data have not been corrected. Using the data, generate a calibration curve and determine the R2 value for the graph using all data including the blank. Report the R2 to 3 decimal places. Using the calibration curve from the previous question, calculate the concentration of iron in a check standard based on the following data: Absorbance = 0.343, 0.345, 0.338, 0.342, 0.339. Also calculate the uncertainty as the standard deviation of x (see equation 4-27 in the textbook) associated with the check standard concentration using LINEST. Report the concentration and uncertainty to the appropriate number of significant figures. To calculate the 95% confidence interval associated with your answer to the previous question, you would need to multiple sx by which t-value? Report your answer to at least three decimal places. If the known concentration of the check standard (from Question 4) is 15.27 mg/L, what is the percent recovery?

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Related questions

Internal Standards

Some analytical methods are subject to one or more common sources of variability in the instrument response. One method aimed at overcoming this variability is the internal standard method. In this method, a known amount of a compound similar to the analyte is added to each standard and sample. Since we know the concentration of the internal standard (IS), we can use the IS response as an indicator of variability. In this type of calibration curve, the quantity plotted on the y-axis is not simply the instrument signal for the analyte, but rather the ratio of the analyte signal to the IS signal.

The IS method is commonly used in gas chromatography, because of the variability inherent in the small volumes injected into the instrument. In the forensic lab, blood alcohol measurements are one of the most common analyses performed. This dry lab example will use blood alcohol data.

You will use ethanol standards that you have purchased. You have 5 of these, with concentrations of 0.050, 0.080, 0.100, 0.200, and 0.300 %w/v of ethanol. You also have a blank, which doesnât contain any ethanol.

You will use n-propanol as the internal standard. You have made up a 0.0300% (v/v) solution of propanol.

You have one sample to run.

You add 2 mL of each of the standards and the sample to GC vials. Then you add 0.450 mL of the internal standard n-propanol to each vial. You get the data below.

Ethanol concentration, % (w/v)	Peak area for ethanol (pA*sec)	Peak area for n-propanol pA*sec)	Ratio of ethanol area to propanol area

First, make a calibration curve using only the area of the ethanol peak and the concentrations of the standards. As in Part 1 a and b, prepare and print a calibration curve including the linear least squares equation of the line equation and the R² value, and print a copy for your report. Also, calculate the concentration of your sample and the uncertainty (95% confidence interval), as well as the uncertainty of the unknown determination on a percentage basis, and include these values in your report. .

Next, make a calibration curve based on the ratio of ethanol area to propanol area and the concentrations of the standards. As in the previous question, prepare and print a calibration curve including the linear least squares equation of the line equation and the R² value, and print a copy for your report. Also, calculate the concentration of your sample and the uncertainty (95% confidence interval), as well as the uncertainty of the unknown determination on a percentage basis, and include these values in your report. .

At a blood alcohol concentration of 0.08% (w/v) or more a person is considered impaired. Briefly discuss whether the calculated results for the sample in e and f above support criminal charges of impairment.

Report Requirements:

Spreadsheet with graphs and calculations. Prepare separate sheets in one excel file for each of the following:

Data Set 1

Data Set 2

Calibration with external standard

Standard addition with one standard (optional, could submit hand or type written calculation only)

Standard addition with multiple additions

Internal standard peak areas

Internal standard peak area ratios

Print-outs of graphs

Data Set 1

Data Set 2

Calibration with external standard

Standard addition with multiple additions

Internal standard peak areas

Internal standard peak area ratios

Results

Fill in the table below with results from the spreadsheet. Remember to include units.


	Concentration of unknown	Uncertainty of unknown	Uncertainty of unknown in terms of %

	Concentration of unknown	Uncertainty of unknown	Uncertainty of unknown in terms of %

2d	Concentration of unknown	Uncertainty of unknown	Uncertainty of unknown in terms of %

	Concentration of unknown	Uncertainty of unknown	Uncertainty of unknown in terms of %

	Concentration of unknown	Uncertainty of unknown	Uncertainty of unknown in terms of %

Short answers/additional tables

Section 1c:

Section 1d:

Section 1e2:

Section 2a Table:

Section 3b Table:

Section 3b4 calculation

Section 3b5

Section 4d Table with calculated ratios

Section 4g

Hello, everyone,,kinda have trouble with a challenging chem hwproblem. I dont need A, i just need help in B) and C)....i thinkits just so much information that it threw me off. Please i willonly award points if the person include units and sig figs. Pleaseonly help me if ur sure.