Be sure to download the instructions relating to the Excel spreadsheets for experiments #5 (pH) and #6 (SP) at the bottom of this worksheet if necessary.
In this page, you will be able: (1) view YouTube videos that demonstrate the use of Microsoft Excel and (2) view Excel spreadsheets that were discussed in lecture (available for download by clicking on the down arrow symbol on the appropriate lines at the bottom of this page).
CHEM 310 Learning Goals relating to Microsoft Excel:
1. General. To understand the basic aspects of using Microsoft Excel 2010 and/or 2013, including such topics as: (1) understanding how spreadsheet cells may contain either text, values, formulas, or functions), (2) how to format these cells (font, alignment, number formats, merging of cells, etc.), (3) how to prepare, use, and analyze x-y graphs using the data that you have entered into those cells.
2. SP Experiment. To learn the basic principles of least-squares linear regression (obtaining the best straight line that fits a series of data points) and apply this concept to prepare a Beer's Law calibration curve. In addition, the results obtained using this plot will be used to determine the concentration of iron in an unknown solution, and from that data, you will calculate the per cent of iron in a ferrous ammonium sulfate unknown. Please first watch these two YouTube videos:
Assignment: load the spreadsheet Sample Spectrophotometric data.xls below and practice creating different types of graphs and entering trendlines.
3. pH Experiment. To learn how to prepare x-y scatter plots that involve curves - specifically acid-base titration curves involving three different titrations with sodium hydroxide: (1) titration of a strong acid), (2) titration of a weak acid, and (3) titration of a polyprotic acid (phosphoric acid). These graphs will then be analyzed to locate the equivalence point of these three titrations, calculate the dissociation constant and equivalent weight of the unknown solid weak acid, and calculate the dissociation constants of phosphoric acid and the molarity of the unknown phosphoric acid solution.
4. Other Applications. In addtions, students will become familiar with ways in which how Microsoft Excel may be used to understand a variety of concepts discussed in Quantitative Analysis.
Alpha (Fractional Composition) Digrams
Alpha (Fractional Composition) diagrams are widely used to graphically show how the fraction (alpha) of [HA] and [A-] varies with the pH in weak acid systems such as a mixture of acetic acid and sodium acetate. Please watch the following YouTube video. The first portion (up to about 3:52) is a bit detailed, but the remainder (from 3:52 to the end, 7:11) is especially important for you to understand.
Alpha diagrams for both monoprotic acid systems (such as acetic acid-sodium acetate and formic acid-sodium formate systems) and polyprotic acid systems (such as carbonate and phosphate systems) may easily be generated using the spreadsheet Fractional Composition Diagram.xls that you may download and use below.