* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Introduction to Chemical Reactions
Elias James Corey wikipedia , lookup
Cracking (chemistry) wikipedia , lookup
Discodermolide wikipedia , lookup
Fischer–Tropsch process wikipedia , lookup
Enantioselective synthesis wikipedia , lookup
Marcus theory wikipedia , lookup
Asymmetric induction wikipedia , lookup
Woodward–Hoffmann rules wikipedia , lookup
Ring-closing metathesis wikipedia , lookup
Physical organic chemistry wikipedia , lookup
Vinylcyclopropane rearrangement wikipedia , lookup
Tiffeneau–Demjanov rearrangement wikipedia , lookup
Ene reaction wikipedia , lookup
Diels–Alder reaction wikipedia , lookup
Hydroformylation wikipedia , lookup
Hofmann–Löffler reaction wikipedia , lookup
Baylis–Hillman reaction wikipedia , lookup
Petasis reaction wikipedia , lookup
Wolff–Kishner reduction wikipedia , lookup
Introduction to Chemical Reactions { Types of Chemical Reactions All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Chemical Reactions Matter is combined or broken apart to form a new type of matter Bonds are broken, atoms rearranged, and new bonds are reformed Chemical reaction is a change in which one or more substances are converted into new substances The substances that react are called reactants The new substances produced are called products This relationship can be written as: Produce Reactants Products All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Evidence (signs) of a Chemical Reaction Release of a gas Change in temperature Evidence - solution changes color Formation of a precipitate Evidence – Temperature goes up (exothermic) Evidence – Temperature goes down (endothermic) Change in color Evidence - Bubbles Evidence - forms and settles to the bottom Energy is released Evidence - light or sound All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Symbols Used in Chemical Reactions Symbol Meaning of Symbol (s) A reactant or product in the solid state; also used to indicate a precipitate (l) A reactant or product in the liquid state (g) A reactant or product in the gaseous state (aq) A reactant or product in an aqueous solution (dissolved in water) → Used to indicate the direction of a reaction. Translated as “yields” of “produces”. All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Parts of a Chemical Equation Reactants Yield sign Products Coefficients Subscripts HgO(s) Reactants Hg(l) + O2(g) Products “Yields” Indicates result of reaction All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Types of Chemical Reactions Synthesis Decomposition Single Replacement Double Replacement Combustion All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Synthesis Reaction Generic Form: Reactants: A and B are either elements or simple compounds Products: A + B → AB AB is a complex compound formed from A and B Reaction Mechanism: The atoms of A and B are bonded together to form a single new compound All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Examples of Synthesis Reactions 2 Na + Cl2 → 2 NaCl Sodium atoms and chlorine gas molecules combine to form a single new product Sodium chloride is the product of the reaction 2 Mg + O2 → 2 MgO Magnesium atoms and oxygen gas molecules combine to form a single new product Magnesium oxide is the product of the reaction In a moment, we will also see that this reaction can also be classified as a combustion reaction All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Decomposition Reaction Generic Form: Reactants: AB is a complex compound formed from A and B Products: AB → A + B A and B are either elements or simple compounds Reaction Mechanism: The compound AB breaks down into its elements or into simple compounds All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Examples of Decomposition Reactions 2 H2O2 → 2 H2O + O2 Hydrogen peroxide molecules break down to form new products that are simple molecules Water and oxygen gas are the products of the reaction 2 KClO3 → 2 KCl + 3 O2 Potassium chlorate molecules break down when heated to form new products that are simple molecules Potassium chloride and oxygen gas are the products of the reaction All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Combustion Reaction Generic Form: Reactants: A + O2 → H2O + CO2 A is a hydrocarbon (a compound of hydrogen and carbon) O2 is oxygen gas (we will assume more than enough oxygen is present) Products: When combusting a hydrocarbon, the products will always be water and carbon dioxide Reaction Mechanism: The hydrocarbon is oxidized and produces energy With a hydrocarbon the reaction is generally rapid All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Examples of Combustion Reactions C2H4 + 3 O2 → 2 CO2 + 2 H2O Ethene (also known as acetylene) is a hydrocarbon When O2 is a reactant, the reaction must be combustion The products must be water and carbon dioxide All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Single Replacement Reaction Generic Form: Reactants: A is a metal element BY is an ionic compound Products: A + BY → AY + B AY is an ionic compound B is a metal element or a diatomic molecule Reaction Mechanism: A and B are elements of the same type If A is more reactive than B, the reaction occurs with A replacing B If A is less reactive than B, no reaction can occur All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Examples of Single Replacement Reactions 2 Al(s) + 3 CuCl2(aq) → 2 AlCl3(aq) + 3 Cu(s) Aluminum is a metal and copper is the metal in the ionic compound Aluminum is more reactive than copper, therefore the reaction occurs The aluminum replaces the copper ion in the ionic compound and the element copper forms as a precipitate What happens if the reaction is reversed? Cu(s) + AlCl3(aq) → No reaction occurs The copper is not more reactive than the aluminum, so no reaction occurs All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Double Replacement Reaction Generic Form: Reactants: AX is an ionic compound BY is an ionic compound Products: AX + BY → AY + BX AY is an ionic compound BX is a an ionic compound Reaction Mechanism: A and B are elements of the same type (both are metals ) as are X and Y (both are non-metals) A replaces B and X replaces Y (the ions trade partners) If an insoluble product (precipitate or insoluble gas) is produced, the reaction occurs All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Examples of Double Replacement Reactions Na2SO4(aq) + Ba(NO3)2(aq) → 2 NaNO3 (aq) + BaSO4(s) The ions in the two ionic compounds change partners and form two new ionic compounds BaSO4 is not soluble in water BaSO4 is the product of the reaction What happens if there is no precipitate? Na2SO4(aq) + KNO3 (aq) → No Reaction The ions of sodium, potassium, sulfate, and nitrate cannot produce an insoluble product Therefore, there is no product of the reaction and that means there is no reaction between the sodium sulfate and the potassium nitrate All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Types of Chemical Reactions Summary All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source. Key Terms Combustion Reaction A + O2 → Oxidized Metal or CO2 + H20 Decomposition Reaction AB → A+ B Double replacement Reaction AX+ BY → AY + BX Single replacement Reaction A + BY → AY + B Synthesis Reaction A+ B → AB All content by HST Educational Innovations © 2012. All rights reserved. Use of this material is invited with proper attribution to the source.