Hw1K-G1-Matter - HW Set 1 - KEY GENERAL CONCEPTS of MATTER...

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HW Set 1 - KEY GENERAL CONCEPTS of MATTER CHM2045 Hw1k-G1-Matter.wpd 1. a) copper - solid metal b) isopropyl alcohol - colorless liquid c) carbon dioxide - colorless gas d) carbon (diamond) - colorless, crystalline solid e) bromine - orange liquid f) sodium hydrogen carbonate (baking soda) - white, crystalline solid g) chlorine - yellow gas 2. a) tap water - liquid homogeneous mixture (solution) of water,±dissolved minerals, perhaps chemical additives, dissolved gases -if sediment is present, then a heterogeneous mixture b) distilled water - pure substance (compound) c) gasoline - liquid homogeneous mixture of different hydrocarbon compounds and anti- knock additives d) bromine liquid and its vapor - pure element in two phases e) cube of sugar - pure compound (sucrose) sugar solution - liquid homogeneous mixture of the compounds sugar and water (presumably) g) sugar solution with sugar crystals on the bottom - heterogeneous mixture of solid sugar and liquid solution of water and sugar h) Bufferin tablet - solid particles of different compounds (aspirin, buffering agents, binders) that are compressed to form a tablet i) nitrogen gas - pure substance (element) j) brass - homogeneous mixture (one solid phase) of the metallic elements copper(67%) and zinc(33%) called an "alloy" k) partially molten iron - pure element in two phases (solid and liquid) l) iodized salt - two compounds, sodium chloride and a trace of sodium iodide m) ink, containing a soluble dye and suspension of fine particles of carbon - heterogeneous mixture of ink solution (liquid solvent and dyes) and solid particles of carbon n) battery fluid - of the compounds water, sulfuric acid, and lead salts o) 24 karat gold - pure metallic element p) 14 karat gold - solid homogeneous mixture of gold (58%) and other metals to increase hardness q) air - homogeneous mixture (a solution) of oxygen, nitrogen, some carbon dioxide, water vapor, and other elements and compounds 3. Total mass of the solution = 10.0 g + 300. g 310. g % salt = 10.0 g x 100 3.23 % % H 2 O = 300. g = 96.8 % Note that a solution is by definition, a homogeneous mixture, and its component proportions may be varied. A pure compound, on the other hand, is also homogeneous, but its elemental proportions are fixed. 4. a) Mass oxygen Mass Al 2 O 3 - Mass Al 7.99 g - 4.23 g 3.76 g oxygen % Al = 4.23 g 52.9 % % O = 3.76 g = 47.1 % 7.99 g
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2 4. continued b) 1st Experiment Mass Cl consumed = Mass NaCl - Mass Na 2.54 g 1.00 g 1.54 g Cl % Cl = 1.54 g x 100 60.6 % % Na = 1.00 g = 39.4 % 2.54 g 2nd Experiment Mass Na consumed Mass Cl 1.56 g 0.65 g Na = = 60.6 % = 0.65 g = 39 % 1.65 g Both products analyze for the same percent-by-mass elemental composition, consistent the Law of Definite Proportions for any pure compound. c) 0.625 g C x 100. g sucrose x 6.5 g H 0.096 g H 42.1 g C 100. g sucrose 0.625 g C x 51.40 g O 0.763 g O d) 10.0 g Si x 100. g SiO 2 21.4 g SiO 2 46.7 g Si 5. a) Gold is obtained from river sand by panning . Physical process: The element gold
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Hw1K-G1-Matter - HW Set 1 - KEY GENERAL CONCEPTS of MATTER...

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