6.1: Pre-Lab assignment
- Page ID
- 409180
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)
( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\id}{\mathrm{id}}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\kernel}{\mathrm{null}\,}\)
\( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\)
\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\)
\( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)
\( \newcommand{\vectorA}[1]{\vec{#1}} % arrow\)
\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow\)
\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vectorC}[1]{\textbf{#1}} \)
\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)
\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)
\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
In this experiment, you will work with several of your lab mates as a group to address these research questions:
- Are there detectable amounts of toxic Pb in the water sources across Duke's campus?
- How well does a commercial water filter remove Pb and other elements from drinking water that contains Pb?
In addition, you will perform qualitative analysis on your water sample to detect the presence of elements of your choice.
Pre-Lab assignment:
You should work with your group to complete the pre-lab assignment. Each group member should collect one water sample. Collaborate with your group to plan a strategy to calibrate the instrument and make quantitative determinations of Pb concentrations in your water samples.
- Read the entire contents of this module, and review the Methods of Calibration.
- Read this article about Pb detected in the water from a UNC campus dorm: https://www.dailytarheel.com/article/2022/09/university-hamilton-hall-lead-short
- Collect unique water samples from somewhere on our campus (refer to the Pb google map to see where others have already gathered samples, and to the procedure for instructions). Bottles are available for sample collection - ask your instructors.
- Read the claims about the efficiency of Brita water filters for removal of substances from drinking water. (https://www.brita.com/why-brita/better-water/) You will use a standard Brita pitcher filter in this experiment. Determine what efficiency you expect for filtration of Pb from tainted water.
- What is the minimum acceptable concentration for Pb in drinking water according to the EPA?
- Each of you should identify at least one other element that you will measure; this should be an element that you expect to be in a drinking water sample. Your group can choose to analyze up to 10 elements (...or more if you can convince us that it makes sense).
- Plan how you will create the tainted water sample described in the procedure.
- With your group, plan how you will calibrate the instrument for quantitative determination of Pb in your source water, tainted water, and filtered water samples.
- In writing, please explain the principle of standard addition and describe how it is different than a method using external calibration.
- Describe the contexts in which standard addition should be used as a calibration method and discuss the advantages of standard addition over other methods of analysis.
- Describe which calibration method your group will use, and give specific details (ie a protocol) for how your calibration solutions will be made during your next lab period.