Balancing Equations and Identifying Reaction Types

Why do we balance equations?

Writing Chemical Equations Reactants  Products

Writing Chemical Equations Word Equation: Iron metal reacts with oxygen gas and forms solid iron (III) oxide Chemical Equation:

Writing Chemical Equations Balanced Chemical Equation: 4 Fe (s) + 3 O2(g) 2 Fe2O3 (s)

Balancing Equations Example 1

Balancing Equations Example 2

Dalton’s Atomic Theory All elements are composed of indivisible particles called atoms Atoms of the same element are identical. The atoms of any one element are different from those of any other element. Atoms of different elements can physically mix together or chemically combine with one another in simple whole number ratios to form compounds.(law of definite composition) Chemical rxns occur when atoms are separated, joined, or rearranged. Atoms of one element, however, are never changed into atoms of another element as a result of a chemical reaction.(law of conservation of mass)

Balancing Equations Guidelines 1 . Write the correct chemical formulas for the reactants and the products 2. Include states of matter if necessary (s, l, g, aq)

Balancing Equations Guidelines 3. Count the number of atoms of each element in the reactants and products 4. Balance the elements one at a time using coefficients; never change subscripts ---see part a,b,c

Balancing Equations Guidelines 4a. Treat polyatomic ions appearing on both sides of rxn as one unit and balance first 4b. Balance atoms that appear once on each side of the equation 4c. Balance H and O last

Balancing Equations Guidelines 5. Check Work 6. Coefficients should be in lowest possible ratios

Balancing Equations Guidelines Write formulas States of matter Count atoms Balance using coefficients Check work Coefficients in lowest ratios?

Predicting Products Combination: Mg + O2  Decomposition: Ca(ClO3)2  Single: Cu + AgNO3  Double: KI + Pb(NO3)2  Combustion: CH4 + O2 

Predicting Products 1. Combination Mg + O2 

Predicting Products

Predicting Products 2. Decomposition Ca(ClO3)2 

Predicting Products 3. Single Replacement Cu + AgNO3 

Predicting Products

Predicting Products 4. Double Replacement KI + Pb(NO3)2 

Predicting Products

Predicting Products 5. Combustion CH4 + O2 

Reaction Types

Reaction Types

Balancing Equations Practice Write a balanced equation for each of the following chemical reactions:

Balancing Equations Practice Aluminum metal reacts with aqueous hydrochloric acid to form hydrogen gas and aqueous aluminum chloride.

Balancing Equations Practice Acetylene gas (C2H2) burns in a welding torch with oxygen to form carbon dioxide and water. Balancing Equations Practice

Balancing Equations Practice Copper metal and aqueous silver nitrate react to form copper(II) nitrate and silver metal

Balancing Equations Practice Aluminum metal reacts with oxygen to form aluminum oxide

Balancing Equations Practice Barium Chlorate decomposes into barium chloride and oxygen gas

Balancing Equations Practice Balance each equation and tell what type of reaction it represents.

Balance and Identify RXN Type _Fe + _Br2  _FeBr3 _C6H14+_ O2  _CO2 +_ H2O

Complete and balance the following reactions: SrCO3  Li + H2O  Li3PO4 + Zn(NO3)2  C3H8 + O2  C2H5OH + O2 

Activity Series of Metals Lab Single Replacement Reactions = An elements switches places with another element in a compound to form a new compound and element Example: 2Al + 3Fe(NO3)2  2Al(NO3)3 + 3Fe

Activity Series of Metals Lab Reactivity – the ability of an element to react

Activity Series of Metals Lab Activity Series – list of elements organized according to ease at which elements undergo certain chemical reactions

Activity Series of Metals Lab A reactive metal will replace any metal listed below it in the activity series

Will these rxns occur? Li + MgCl2  Pb + AlCl3  Note: These are single replacement reactions. A + BC  AC + B

Activity Series of Metals Li>K>Ba>Ca>Na>Mg>Al>Mn>Zn>Cr>Fe> Co>Ni>Sn>Pb>H>Cu>Ag>Hg>Pt>Au