Midterm notes - -Heterogeneous matter The composition is...

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--Heterogeneous matter. The composition is not uniform (i.e. sand, salt and water) (can be separated by physical means like filtering). --Homogenous matter. The compostition is uniform. (Needs to be separated chemically). Can be classified as “pure substance(composition does not vary)” or “homogenous mixture(also called solution)(composition varies)”. Pure substances (are element and compound). Element can not be separated into simpler substances. Compound can be separated. -- °K= °C+273.15 °C= 5/9 (°F-32) °F=9/5 (°C)+32 Density= mass/volume ; Volume= mass/density ; Mass= (volume)(density) --Properties of matter. Physical: can be observed w/o changing the substance into another (boiling temp, density, mass, volume). Chemical: observed when the substance is changed into another (gas igniting, corrosiveness). Intensive: Independent of the amount of substance (density, color). Extensive: dependent of the amount of substance (mass, energy, volume). --Separation of mixtures. Distillation (separates homogeneous mixtures by difference in boiling points), filtration (separates solids from liquids and solutions), chromatography (separates substances by difference in solubility in a solvent). --Significant figures: for add & sub answer is rounded to the least significant decimal place. of significant figures in any of the numbers used in the calculation. --Accuracy: the proximity of a measurement to the true value of quantity. Precision: the proximity of several measurements to each other. -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- --Law of constant composition: In a given compound the relative number and kind of atoms are constant. Law or conservation of mass: the total amount of mass present at the end of a reaction is the same as before the reaction. Law of multiple proportions: H20 or H2O2 (same elements, different proportions). --Cathode rays are electrons.
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This note was uploaded on 06/03/2009 for the course CHEM 201 taught by Professor Gjid during the Fall '07 term at Richard J. Daley College - CCC.

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