* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download CO 2(g) - cloudfront.net
Photoredox catalysis wikipedia , lookup
IUPAC nomenclature of inorganic chemistry 2005 wikipedia , lookup
Fluorochemical industry wikipedia , lookup
Inorganic chemistry wikipedia , lookup
California Green Chemistry Initiative wikipedia , lookup
Fine chemical wikipedia , lookup
Chemistry: A Volatile History wikipedia , lookup
Asymmetric induction wikipedia , lookup
Marcus theory wikipedia , lookup
Multi-state modeling of biomolecules wikipedia , lookup
Isotopic labeling wikipedia , lookup
History of molecular theory wikipedia , lookup
Gas chromatography–mass spectrometry wikipedia , lookup
Chemical equilibrium wikipedia , lookup
Rate equation wikipedia , lookup
Chemical potential wikipedia , lookup
Chemical weapon proliferation wikipedia , lookup
Atomic theory wikipedia , lookup
Enantioselective synthesis wikipedia , lookup
Safety data sheet wikipedia , lookup
George S. Hammond wikipedia , lookup
Al-Shifa pharmaceutical factory wikipedia , lookup
Photosynthetic reaction centre wikipedia , lookup
Chemical weapon wikipedia , lookup
Organic chemistry wikipedia , lookup
Chemical plant wikipedia , lookup
Chemical industry wikipedia , lookup
Chemical Corps wikipedia , lookup
Registration, Evaluation, Authorisation and Restriction of Chemicals wikipedia , lookup
Drug discovery wikipedia , lookup
Evolution of metal ions in biological systems wikipedia , lookup
Process chemistry wikipedia , lookup
History of chemistry wikipedia , lookup
Bioorthogonal chemistry wikipedia , lookup
Electrochemistry wikipedia , lookup
Hydrogen-bond catalysis wikipedia , lookup
Physical organic chemistry wikipedia , lookup
Photosynthesis wikipedia , lookup
Strychnine total synthesis wikipedia , lookup
Click chemistry wikipedia , lookup
Lewis acid catalysis wikipedia , lookup
VX (nerve agent) wikipedia , lookup
Transition state theory wikipedia , lookup
Chemical reaction wikipedia , lookup
Chemical Reactions Mr. Matthew Totaro Legacy High School Honors Chemistry Chemical Reactions • Reactions involve chemical changes in matter resulting in new substances. • Reactions involve rearrangement and exchange of atoms to produce new molecules. Elements are not changed into new elements during a reaction. Thermite Reaction 2 Example of a Chemical Reaction Reactants Products 3 Evidence for a Chemical Reaction • Look for evidence of a new substance. • Visual clues (permanent). Color change. Precipitate formation. Solid that forms when liquid solutions are mixed. Gas bubbles. Large energy changes. Container becomes very hot or cold (transfer of heat). Emission of light. • Other clues. New odor. Whooshing sound from a tube. Permanent new state. 4 Evidence of a Chemical Change Release or Absorption of Heat Color Change Formation of a Gas Emission of Light Formation of Solid Precipitate 5 Evidence of Chemical Change, Continued • In order to be ABSOLUTELY SURE that a chemical reaction has taken place, you need to go down to the molecular level and analyze the structures of the molecules at the beginning and at the end. Is boiling water a chemical change? 6 Practice—Decide Whether Each of the Following Involve a Chemical Reaction. • Photosynthesis • • • • • Yes, CO2 and H2O combine into carbohydrates Heating sugar until it turns black Yes, sugar decomposing Heating ice until it turns liquid No, molecules still same Yes, food decomposing and combining Digestion of food with stomach acid Dissolving sugar in water No, molecules still same Burning of alcohol in a flambé dessert Yes, alcohol combining with O2 to make CO2 and H2O 7 Chemical Equations Concise representation of a chemical reaction The Combustion of Methane • Methane gas burns to produce carbon dioxide gas and gaseous water. Whenever something burns it combines with O2(g). 9 Anatomy of a Chemical Equation CH4 (g) + 2 O2 (g) CO2 (g) + 2 H2O (g) Anatomy of a Chemical Equation CH4 (g) + 2 O2 (g) Reactants appear on the left side of the equation. CO2 (g) + 2 H2O (g) Anatomy of a Chemical Equation CH4 (g) + 2 O2 (g) CO2 (g) + 2 H2O (g) Products appear on the right side of the equation. Anatomy of a Chemical Equation CH4 (g) + 2 O2 (g) CO2 (g) + 2 H2O (g) The states of the reactants and products are written in parentheses to the right of each compound. Anatomy of a Chemical Equation CH4 (g) + 2 O2 (g) Coefficients are inserted to balance the equation. CO2 (g) + 2 H2O (g) Subscripts and Coefficients Give Different Information • Subscripts tell the number of atoms of each element in a molecule Subscripts and Coefficients Give Different Information • Coefficients tell the number of molecules Symbols Used in Equations • Symbols used to indicate state after chemical. (g) = gas; (l) = liquid; (s) = solid. (aq) = aqueous = dissolved in water. • Energy symbols used above the arrow for decomposition reactions. ∆ = heat. hv = light. shock = mechanical. elec = electrical. 17 Law of Conservation of Mass “We may lay it down as an incontestable axiom that, in all the operations of art and nature, nothing is created; an equal amount of matter exists both before and after the experiment. Upon this principle, the whole art of performing chemical experiments depends.” --Antoine Lavoisier, 1789 Conservation of Mass in a Reaction • In a chemical reaction, matter cannot be created or destroyed. Therefore, the total mass cannot change. And the total mass of the reactants will be the same as the total mass of the products. • In a chemical reaction, all the atoms present at the beginning are still present at the end. If all the atoms are still there, then the mass will not change. 19 Balancing Example • When magnesium metal burns in air, it produces a white, powdery compound magnesium oxide. Mg(s) + O2(g) → MgO(s) 20 Another Balancing Example • Under appropriate conditions at 1000°C, ammonia gas reacts with oxygen gas to produce gaseous nitrogen monoxide and steam NH3(g) + O2(g) → NO(g) + H2O(g) 21 Reaction Types Synthesis (Combination) Reactions • the combination of 2 or more substances to form a compound • only one product A + B AB Synthesis (Combination) Reactions • Two or more substances react to form one product • Examples: N2 (g) + 3 H2 (g) 2 NH3 (g) C3H6 (g) + Br2 (l) C3H6Br2 (l) 2 Mg (s) + O2 (g) 2 MgO (s) 2 Mg (s) + O2 (g) 2 MgO (s) Decomposition Reactions • a compound breaks down into 2 or more simpler substances • only one reactant AB A + B Decomposition Reactions • One substance breaks down into two or more substances • Examples: CaCO3 (s) CaO (s) + CO2 (g) 2 KClO3 (s) 2 KCl (s) + O2 (g) 2 NaN3 (s) 2 Na (s) + 3 N2 (g) Combustion Reactions • the burning of any substance in O2 to produce heat A + O2 B CH4(g) + 2O2(g) CO2(g) + 2H2O(g) Combustion Reactions • Rapid reactions that produce a flame • Most often involve hydrocarbons reacting with oxygen in the air • Examples: CH4 (g) + 2 O2 (g) CO2 (g) + 2 H2O (g) C3H8 (g) + 5 O2 (g) 3 CO2 (g) + 4 H2O (g) Whoosh Bottle Demo is a Combustion Reaction 30 Single Replacement • one element replaces another in a compound metal replaces metal (+) nonmetal replaces nonmetal (-) A + BC B + AC C. Johannesson Single Replacement Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s) C. Johannesson Double Replacement • ions in two compounds “change partners” • cation of one compound combines with anion of the other AB + CD AD + CB C. Johannesson Double Replacement Pb(NO3)2(aq) + K2CrO4(aq) PbCrO4(s) + 2KNO3(aq) C. Johannesson Practice—Classify the Following Reactions as Synthesis, Decomposition, Single Displacement, or Double Displacement. 3 Mg(s) + 2 FeCl3(aq) 3 MgCl2(aq) + 2 Fe(s) CO2(g) + H2O(l) H2CO3(aq) 3 KOH(aq) + H3PO4(aq) K3PO4(aq) + 3 H2O(l) CaCO3 ( s ) CaO(s ) CO 2 ( g ) 35 Practice—Classify the Following Reactions as Synthesis, Decomposition, Single Displacement, or Double Displacement, Continued. 3 Mg(s) + 2 FeCl3(aq) 3 MgCl2(aq) + 2 Fe(s) Single displacement. CO2(g) + H2O(l) H2CO3(aq) Synthesis. 3 KOH(aq) + H3PO4(aq) K3PO4(aq) + 3 H2O(l) Double displacement. CaCO3 ( s ) CaO(s ) CO 2 ( g ) Decomposition. 36 Reaction Prediction Synthesis Reactions A + B AB Two substances combine to form a single compound. Al (s) + O2 (g) 2 elements combine to form a single compound Decomposition Reactions AB A + B One compound breaks down into multiple substances (usually because of the presence of heat). K2CO3 (s) ∆ Metal carbonate + heat → metal oxide + carbon dioxide gas Combustion Reactions A + O2 CO2 + H2O CH4 (s) + O2 (g) One substance reacts with Oxygen to form Carbon Dioxide and Water Single Replacement Reactions A + BC B + AC Cu (s) + AgNO3 (aq) A more active metal replaces a metal in a compound to form a new compound and an element Double Replacement Reactions AB + CD AD + CB AgNO3 (aq) + KCl (aq) Two compounds exchange partners to form two new compounds