1. General Chemistry 0150 Instructor: Professor Voytek Fall 2010 Chapter 3: Measurements and Problem Solving
2. WHAT IS CHEMISTRY? Chemistry is the study of matter and its properties , both at the macroscopic as well as at the atomic , subatomic and molecular levels. Chemists seek to understand the composition of matter, the changes that matter undergoes as well as the energy associated with these changes. Matter is anything that has mass and volume . It is the stuff of life. Everything around us (including us) is made up of matter.
3. SOME DEFINITIONS Chemical Properties those which the substance shows as it interacts with, or transforms into, other substances Change(s) in composition but mass is conserved Matter anything that has mass and volume -the “stuff” of the universe. Composition What the matter is made of and how much each substance is present. Properties The characteristics that give each substance a unique identity . Physical (Intensive) Properties those which the substance shows by itself without interacting with another substance No change(s) in composition (such as State of Matter)
7. Some Characteristic Properties of Copper DESCRIBING MATTER according to its PROPERTIES Physical Properties reddish brown, metallic luster easily shaped into sheets (malleable) and wires (ductile) good conductor of heat and electricity density = 8.95 g/cm 3 melting point = 1083 ° C boiling point = 2570 ° C Chemical Properties slowly forms a basic blue-green sulfate in moist air reacts with nitric acid and sulfuric acid slowly forms a deep-blue solution in aqueous ammonia
12. I-Clicker Question Frost forms as the temperature drops on a humid winter night. A)physical change ? B)chemical change ?
13. I-Clicker Question A sunflower grows from a seed that is watered and fertilized. A)physical change ? B)chemical change ?
14. Mixtures can be converted to pure substances by a physical processes such as through a filtration, distillation, chromatography, centrifuging, evaporation or sublimation to name a few.
15. Mixtures can be converted to pure substances by a physical processes such as through a filtration, distillation, chromatography, centrifuging, evaporation, extraction, reverse osmosis or sublimation.
16. A magnet can be used to separate iron metal from crystals of potassium dichromate:
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Editor's Notes
Pure substance one type of atom or molecule that is bonded together Mixture two or more different atoms or molecules that are not bonded together Element two or more like atoms bonded together (gold, lead oxygen) Compound two or more different atoms bonded together salt, sugar, distilled water) Homogeneous mixture “solutions” that have different atoms not bonded together but has uniform composition (tap water, air, brass-zinc + copper) Heterogeneous mixture “suspensions” that have different atoms not bonded together and has distinguishable parts (salad dressing, Jello with fruit)
