Maths for Chemistry

Simultaneous Equations in Excel for UV/vis Analysis (Matrix Method)

mkseery — Mon, 07 Feb 2011 13:07:49 +0000

We want to solve this problem using Excel. There are two ways to approach it (easily). In this second method, we will look at the matrix method: (The first method is to use circular references)

Two substances, A and B, absorb light according to the Beer-Lambert law A = ecL where e is the extinction coefficient, c is the concentration of the absorbing substance and L is the path length (0.1 dm). If both species are in solution and the absorbance at 300 nm is measured to be 3.5 and the absorbance at 500 nm is 2.3, use simultaneous equations to calculate the concentrations of A and B in the mixed solution. The extinction coefficients, e are:
* At 300 nm, e(A) = 80; e(B) = 150 units
* At 500 nm, e(A) = 52, e(B) = 100 units.

Simultaneous Equations in Excel for UV/vis Analysis (Circular Refs Method)

mkseery — Mon, 07 Feb 2011 13:04:55 +0000

We want to solve this problem using Excel. There are two ways to approach it (easily). In this first method, we will look at the circular references method: (The second method is to use matrices)

van’t Hoff Equation

admin — Sat, 04 Sep 2010 16:43:45 +0000

This resource explains the background to and illustrates the use of the van’t Hoff equation. Along with some details on how it can be used, there are a number of questions to try, with some hints if you need them.

Details of the resource:

some parts of this file have audio, but it is not necessary to use this if you do not have an audio source
Derivation of the van’t Hoff to two forms – one for use in experimental analysis via graphs and one for use algebraically
How to use the van’t Hoff equation to understand how temperature changes affect a reaction
Some questions to try with video/picture tips and hints

Integrated Rate Equations in Kinetics

admin — Mon, 28 Jun 2010 21:04:21 +0000

This resource sumamrises the derviation and use of integrated rate equations in kinetics. Three examples of integrated rate equations are given (zero, first and second order) along with some worked examples and questions to try. Click on the image to access the resource:

Details of Resource:

Demonstrations and downloadable PDFs of the derivations for zero, first and second order equations
Questions with demonstrated worked examples to show you how answers were obtained
Questions to try along with feedback.

One-way ANOVA

admin — Sat, 20 Mar 2010 19:30:46 +0000

This resource provides information on the principles of the ANOVA test and how to carry it out in MS Excel. A worked example is given, along with screen videos on how to use Data Analysis in Excel. There are some questions for you to test your knowledge. Click on the image to access the resource:

Details of Resource:

Background to the ANOVA test and how it is carried out manually
A glossary of terms involved in ANOVA accessible through the top menu bar
Videos of how to conduct the test in Excel
A worked example showing how the test is performed and results analysed
Questions to try with video answers

Titration Calculations

admin — Fri, 19 Mar 2010 20:27:49 +0000

This resource covers the calculations required in volumetric and mass analysis, as well as giving an outline of how to perform a titration. Click on the image to access the resource:

Details of Resource:

Outline of how to perform a titration
Worked examples on titrations in volumetric and mass analysis
Examples for you to try with feedback and answer printouts
Amended with corrections 29-3-10

Basic Statistical Analysis

admin — Wed, 10 Mar 2010 21:25:20 +0000

This resource considers the basic statistic terms and shows how to calculate them, both manually and using Microsoft Excel. There is a worked example and an example for you to try. Click on the image to access the resource.

Details of Resource

This resource contains:

A glossary of basic statistical terms including how they are calculated and what they are useful for
A worked example for each of the basic statistical functions mean, standard deviation and variance, with short videos on how to compute these functions in Microsoft Excel
A short quiz for you to try out to test that you can perform these calculations

Basic Statistics Glossary

admin — Wed, 10 Mar 2010 19:27:59 +0000

This resource is part of the more extensive resource in Basic Statistic Analysis but is given separately here for ease of access.

The glossary covers: count, degrees of freedom, mean, mode, range, sigma notation, standard deviation and variance.

This is a Flash Object – you can interact with it right on this page.

Paired t-test

admin — Wed, 10 Mar 2010 17:49:07 +0000

This resource explains how to conduct a paired t-test, a test that is sometimes more appropriate to you in place of a two sample t-test. The paired t-test is really just a special form of a one sample t-test, where the “true value” is equal to zero. Click on the image to access the paired t-test resource.

Details of Resource

Overview of scenario where a paired t-test would be appropriate
Worked example of a paired t-test question
Paired t-test question with step by step feedback for you to try

Determining Waters of Crystallisation by Titration

admin — Fri, 05 Mar 2010 12:03:36 +0000

This resource shows how to calculate the numbers of water of crystallisation by titration experiment. A worked example is given along with a question for you to try. The resource is embedded below so you can interact with it or click here to view resource on full screen

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