Conservation of Atoms Main Concept: Conservation of atoms makes it possible to compute the masses of substances involved in physical and chemical processes. Chemical processes result in the formation of new substances, and the amount of these depends on the number and the types and masses of elements in the reactants, as well as the efficiency of the transformation

Aspects of Conservation Conservation of Atoms Aspects of Conservation Atoms/Molecules/Formula Units Subscripts of Formulas Chemical Equation Coefficients Gravimetric Analysis How it works and what it tells us Titration How it works and what it tells us

- conservation of atoms allows for interpretation and analysis of many chemical processes on macroscopic scale - number of atoms, molecules, or formula units in a given mass of substance can be calculated (ex: Avogadro’s number) - subscripts in chemical formula represent number of atoms of each type in molecule

2 1 2 1 1 2 6 4 3 3 4 2 - coefficients in balanced equation = relative numbers of particles consumed and created during chemical rxn

- analyte: chemical species being analyzed - gravimetric analysis (analysis by weight): substance is added to a solution that reacts specifically with a dissolved analyte to form a solid (precipitate) - mass of solid formed used to infer initial concentration/ amount of analyte NaCl added AgNO3

- Titration: determine the concentration of an analyte in a solution - Titrant with known concentration reacts specifically with the analyte

- equivalence (point) of the titration: point where analyte is totally consumed by the reacting species in the titrant (ex: molar equivalence) - end point of the titration: event showing equivalence point is reached; often indicated by change in property (such as color)