Chapter 8: Equations and Types of Reactions Chemistry A Time Frame 3-5 days Explain what’s happening in this picture before you continue the notes

Evidence of Chemical Reactions A brief video review of the indicators of a chemical change (unavailable online)

Parts of a reaction Reactants Products Subscript State of Matter Coefficient Arrow means “to yield”

Law of Conservation of Matter The Law of conservation of matter states that matter cannot be created or destroyed, it can only change forms. Therefore, in a chemical reaction the number of atoms, the mass and the charge must be conserved. This means it is the same on both sides of the arrow.

Take Inventory! Reactants Products 4 hydrogens 4 hydrogens 2 Oxygen 2 oxygens To be Balanced they must have the same number of atoms of each elements

Practice Inventory the following reaction:

Online Balancing Tutorials Let’s try this: http://www.wfu.edu/~ylwong/balanceeq/balanceq.html Chembalancer Lab http://www.dun.org/sulan/software/trial/chem1/chemBalancer/default.htm Another Video to review our ideas

More Practice Zn + O2  ZnO HI + H2  H2 + I2

Types of Reactions Reactions are classified into several categories. Combination A + B  AB Decomposition AB  A + B Single Replacement A + BC  AC + B Double Replacement AB + CD AD + CB Combustion CxHy + O2 CO2+ H2O

Combination ___K +___Br2  ___KBr Also known as composition or synthesis ___K +___Br2  ___KBr 2 1 2 Note the diatomic element is written with a supscript! http://genchem.chem.wisc.edu/demonstrations/Gen_Chem_Pages/04chemrxnpage/chemicalreactions.htm

____Zn + ___I2 ____ ZnI2 Composition 2 1 1 1 Another diatomic http://genchem.chem.wisc.edu/demonstrations/Gen_Chem_Pages/04chemrxnpage/chemicalreactions.htm

Decomposition Single Substance breaks down into two or more simpler substances

Single Replacement ___Cu + __AgNO3  __Cu(NO3 )2 + ___Ag A single element replaces a combined element in a compound. ___Cu + __AgNO3  __Cu(NO3 )2 + ___Ag 2 1 2 1

Double Replacement Contains four compounds with metals trading places. ___AgNO3 + ____NaCl  ____NaNO3 + ____AgCl

Combustion Reactions Involve burning

Writing Equations from words Write the formula for each reactant and each product. Your formula MUST be correct. That’s why we learned the polyatomic ions! Remember the diatomic elements H, O, F, Br, I N, Cl. The are written H2, O2, F2, Br2, I2, N2 and Cl2 Add the symbols for states of matter Take inventory of the equation and balance

Examples- try them yourself Magnesium reacts with oxygen gas to form magnesium oxide. When copper reacts with silver nitrate solution to form silver and copper(II)nitrate solution. 2 Mg + O2  2 MgO Cu + 2 AgNO3  Cu(NO3)2 + 2 Ag This is on the test!

Predicting Products Steps Example Determine what type of reaction is being presented. Write the correct formulas for the product(s). Balance the equation. Example Al + CuSO4  CaCl2 + Al(OH)3  Al2(SO4)3 + Cu Ca(OH)2 + AlCl3 Hint: DR This is on the test!