Definitions of Key Terms in Chemistry and Metallurgy

Chemistry Unit 2 Test Review Definitions: Solute - A dissolved substance (being dissolved) Solvent - A dissolving substance (dissolve other substances) Precipitate - Solid that forms from a liquid. (chemical reaction) Catalyst - Helps speed up the reaction without being added to it. Liming - Using lime or calcium oxide to neutralize acidity in lakes. Smelting - Using heat & chemicals to extract a metal from an ore. Flash smelting - separating a metal from its ore by heating ore in an atmosphere of almost pure oxygen. (Benefits: reduced fuel cost and less pollution) Metallurgy- is the technology of obtaining and refining metals. Flotation - is used to concentrate ore. Mining -the process of extracting useful minerals from the surface of the Earth. Remediation - the process of treating contaminated land or water so that it is safe for use again. Ore - rock containing a relatively high proportion of a desirable mineral. Mineral - a naturally occurring solid that has a definite crystal structure and chemical composition Law of conservation of mass: The mass of products must always equal the mass of reactants. Diatomic elements: H, O, F, Br, I, N, Cl. (When by itself always has a 2) Br(l) & I(s) Hydrocarbon - Hydrocarbons are molecular compounds of the elements carbon and hydrogen. Complete combustion formula: CxHy + O2 ➡ CO2 + H20 + energy Incomplete combustion formula: CxHy + O2 ➡ CO + CO2 + H2O + C + energy Difference between the two: Complete combustion is more efficient as it releases the most energy and cleanest flame. (full supply of oxygen) Incomplete combustion is dangerous as it produces carbon monoxide which can kill you. - Soot occurs (carbon) - limited oxygen supply. Acidic Oxides Carbon Dioxide: Carbo dioxide + water yields carbonic acid CO2(g) 1 H2O(l) → H2CO3(aq) Carbonic acid immediately breaks down in water H2CO3(aq) → H1(aq) 1 HCO3 2(aq) - Reaction with water droplets makes rain slightly acidic, hence, rain has an acidity level of 5.6 rather than 7. Nitrogen Oxides: - Cause rail levels below normal (5.6 PH). - It may form from natural causes such as lightning strikes. - Others are by-products from the combustion of fuels. Sulpher dioxide: - **Major contribution to acid precipitation. - Some are produced from volcanic activity. - The majority of combustion is from fossil fuels. - Non-metallic oxides are called acidic oxides because they form acidic solutions with water. Metallic oxides are called basic oxides because they form basic solutions with water. The acidity of carbon,nitrogen, and sulfur oxides causes serious environmental problems. A catalytic converter prevents many automotive pollutants from being emitted into the atmosphere. The basicity of metallic oxides can be used to neutralize unwanted acidity. Neutralization reactions: - Neutralizing stomach acid: Weakly basic substances such as magnesium hydroxide and aluminum hydroxide are used in some antacid products. (help neutralize stomach acid) Predicting products of a reaction: Acids: a chemical substance, usually a liquid, which contains hydrogen and can react with other substances to form salts. Bases: a substance that can accept hydrogen ions in water and neutralize an acid. PH Level1-6 = Acids 7 = neutralize 8-14 = base Patters for types of reactions: 1. SYNTHESIS: A + B ➡ AB 2. DECOMPOSITION: AB ➡ A + B 3. SINGLE DISPLACEMENT: A + BC ➡ AC + B 4. DOUBLE DISPLACEMENT: AB + CD ➡ AD + CB 5. COMBUSTION: CxHy + O2 ➡ CO2 + H20 + Energy 6. INCOMPLETE COMBUSTION: Activity series for metals and non-metals: Metals: Higher up = replaces… Li (most) Au (least). More apart (quicker reaction) Least apart (Slower reaction) Non-metals: Halogens F (most reactive) then reactivity goes down as you go down. Solubility table: First 2 = (aq) products = 1 (aq) and 1 (s)... if both products = (aq) NR 5 Questions from 5.5 - 5.7 Types of Reactions: 1. Synthesis 2. Decomposition 3. Single displacement 4. Double displacement 5. Combustion Balancing, predicting states and products, and identifying the type of reaction: Predicting states: Signs of a chemical change (in a lab): 1. Change in color or smell 2. Energy is released or absorbed (sound, heat, or light) 3. A gas is produced (bubbling) 4. Precipitate: solid forms from two liquid solutions. Neutralization and baking: - Leavening agents make the dough rise. - Leavening agents produce carbon dioxide bubbles that are trapped within the dough. - As the bubbles expand it pushes the dough upward. - For this to occur a neutralization of a carbonate or yeast is needed. - Baking soda is pure sodium hydrogen carbonate. The leavening action of baking soda is activated when it is mixed with an acidic ingredient like fruit juice, vinegar, or buttermilk. Formation of acid rain (synthesis reaction): Formed by Sulfur oxides - S(s) + O2(g) ➡ SO2(g) SO2(g) + O2(g) ➡ SO3(g) SO3(g) + H2O(l) ➡ H2SO4 (aq) Acid rain effect on the environment: - Acidifying Ontario’s lakes - Aquatic life is affected (some die, some can survive only small amounts, and they are not populating as much anymore. - Limestone in Ontarios lakes slowly react and act as an ant-acid. - “Liming” the lakes involves adding calcium oxide or lime to the waters to help neutralize the acidity. Reaction Notes: Left - reactants Right - products Catalyst - Shown with an arrow (Helps speed up a reaction without being absorbed in the reaction)