7.2 Types of Reactions Key Concepts What are the general types of chemical reactions? How did the discovery of subatomic particles affect the classification of reactions? A chemical reaction is used to test for the presence of calcium carbonate in rock

Major Classes of Reactions In order to understand chemical reactions, it is helpful to _____________ them. There are ________ major categories of chemical reactions that scientists recognize…. ______________ ___________ _______________ _____________________ classify five synthesis decomposition single replacement double replacement combustion

General Equation: A + B  AB Synthesis Reactions In a synthesis reaction, two or more substances _______________ to form a ____________ product General Equation: A + B  AB combine single

Synthesis Reactions When iron rusts, iron metal and oxygen gas combine to form one new substance, _________________. iron(III) oxide If the two reactants were dancers, what would they be doing during a synthesis reaction? Joining to dance together

Decomposition Reactions In a decomposition reaction, a compound _________ _________ into two or more ___________ substances. General Equation: AB  A + B breaks down simpler

Decomposition Reactions The decomposition reaction shown demonstrates that it has ______ reactant, but _______ products one two If the initial compound represents two joined dancers, what would they do during a decomposition reaction? Break apart to dance solo

Single-Replacement Reactions In a single-replacement reaction, one ____________ takes the __________ of another element in a ________________. General Equation: A + BC  B + AC place element compound

Single Replacement Reactions The single replacement reaction below shows the reaction between iron, Fe, and an aqueous solution of copper(II) sulfate, CuSO4. Which element does iron, Fe, replace? Copper, Cu

Single-Replacement Reactions Imagine that the reactants below represent three dancers One is dancing solo (element) Two are dancing together (compound) What would these dancers do during a single replacement reaction? The solo dancer would cut in and take another dancer’s place

Double-Replacement Reactions In double-replacement reactions, the __________ portions of two ionic compounds are _______________ positive interchanged Review Question! When writing the formula for an ionic compound, like NaCl, do you place the positive ion first or second? First… Na+ Cl-

Double-Replacement Reactions General Equation: AB + CD  AD + CB Notice that the general equation for a double-replacement reaction always has ______ compounds on the ____________ side and _____ compounds on the ____________ side two reactant two product

Double Replacement Reactions Look at the double-replacement reaction below… On the reactant side, what are the two positive ions? What happens to them on the product side? If this reaction represented two pairs of dancers, what would they do? Pb2+ and K+ They switch compounds They would trade partners

Review Question! What elements are found in a hydrocarbon? Combustion Reactions A combustion reaction is one in which a substance, normally a ______________, combines rapidly with ___________ hydrocarbon oxygen oxygen Hydrocarbon Review Question! What elements are found in a hydrocarbon? hydrogen and carbon

What other two products are formed during combustion reactions? Combustion reactions are exothermic, so one of their products is ______________ energy What other two products are formed during combustion reactions? H2O and CO2

Redox Reactions After _____________ were discovered, scientists also began to classify certain reactions as a ______________ of electrons between atoms A reaction in which electrons are transferred from one reactant to another is called an _____________ - _____________ reaction or a _______ reaction electrons transfer oxidation reduction redox

Reactions as Electron Transfers Calcium oxide, or lime, is produced when calcium burns in the presence of oxygen. In this reaction, the calcium is __________ and the oxygen is ____________. 2Ca + O2  2CaO oxidized reduced Calcium oxide

Oxidation specifically involves the ______ of electrons Reduction specifically involves the ________ of electrons Hint…LEO the lion goes GER LEO = losing electrons oxidation GER = gaining electrons reduction loss Ca  Ca2+ + 2e– gain O + 2e–  O2–

Review Question Correctly identify each type of reaction shown. Single-replacement decomposition

combustion synthesis double-replacement

O + 2e–  O2– (gaining electrons) Ca  Ca2+ + 2e– (losing electrons) oxidation O + 2e–  O2– (gaining electrons) reduction