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Analytical Chemistry - 01 Cheat Sheet (DRAFT) by

- significant figures - stoichiometry - evaluations of analysis - concentration of calculation

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Signif­icant Figures

Reporting Computed Data
- One of the best ways of indicating reliab­ility is to give a confidence limit at the 90% or 95% confidence level.
- Another method is to report the absolute standard deviation or the coeffi­cient of variance of the data.
Rules to Determine the Number of Signif­icant Figures
1. All nonzero digits are signif­icant.
2. An exact number has an infinite number of signif­icant figures.
3. A zero is signif­icant when it is between nonzero digits, at the end of a number that includes a decimal point, before the first nonzero digits, and a trailing zero in a number without a decimal point.
Signif­icant Figures in Calculated Results:
- for addition and subtra­ction, the number of signif­icant figures can be found by visual inspec­tion.
- for products and quotients, the answer should be rounded so that it contains the same number of signif­icant figures as the original number with the smallest number of signif­icant figures.
- in a logarithm of a number, keep as many digits to the right of the decimal point as there are signif­icant figures in the original number.
- in a antilo­garithm of a number, the result should have the same number of signif­icant figures as the number of signif­icant decimal places in the original number.

Stoich­iometry and Concen­tration

Mole Ratio - indicated by coeffi­cients in a balanced equation.
Chemical Reaction - process in which one or more substances is changed into one or more new substa­nces.
Chemical Equation - uses chemical symbols to show what happens during a chemical reaction.

Evaluation of Analytical Data

Mean - arithmetic mean or average.
Median - middle value of a sample of results arranged in order of increa­sin­g/d­ecr­easing magnitude.
- The median is used advant­age­ously when a set of data contains an outlier. An outlier can have a signif­icant effect on the mean but lesser on the median.
Mode - value that occurs most frequently in a set of determ­ina­tions.