CHEM120 Lecture Notes - Mass Spectrometry, Weighted Arithmetic Mean, Stoichiometry

• School: University of Waterloo
• Department: Chemistry
• Course: CHEM120
• Professor: Richard Marta

Document Summary

Stoichiometry is the quantitative study of the composition and mixtures and of the amount of reactants or produces that are involved in a chemical reaction. A compound is composed of two or more elements and has a fixed composition. An example is how water is always 89% oxygen by mass and 11% hydrogen. Another example is ho ethanol is always 52% carbon and 13% hydrogen and 35% oxygen. A mixture, is composed of two or more substances and has a variable composition. For example, water and ethanol can be mixed in any proportion. Basically, stoichiometry is the study and use of the qualitative relations involving the amounts of matter. In labs, we are, almost usually, restricted to using the samples of matter that are large enough to see and manipulate using laboratory equipment. Those samples mostly contain an uncountable number of molecules and atoms; however, counting atoms and molecules directly is simply out of the question.