2basic types of reactions Good News!Of all the millions of possible chemical reactions, there are only5basic types of reactions
3Synthesis Two or more reactants combine to form a product: A + B C C O CO2
4DecompositionThe reverse of synthesis: A compound breaks down into two or more simpler substancesA B CCO C O2
5Single ReplacementA “single” element replaces another element in a compoundA + BX B + AXNa + AgNO Ag + NaNO3
6When will single replacement reactions occur? Use Table J for single replacement reactionsThe higher the element is on the table, the more reactive it is. A reactive element wants to react, and form a compound. It will “bump” a less reactive element out of the compound and take its place.
7Single ReplacementIn this example, Na is more reactive than Ag, so Na bumps Ag out of the nitrate compound and takes its place.Na + AgNO Ag + NaNO3
8Double ReplacementTwo aqueous ionic compounds (dissolved in water) switch positive ions to produce either a precipitate, a gas, or a molecular compound (like water)AB CD AD CBAgNO3(aq)+ NaCl(aq) AgCl(s) + NaNO3(aq)
9Double Replacement Use Table F to determine if a precipitate will form AB CD AD CBAgNO3(aq)+ NaCl(aq) AgCl(s) + NaNO3(aq)
10Combustion Hydrocarbon and oxygen yields carbon dioxide and water and heatCH O CO2 + H2O + heat
11Balancing EquationsMass is always conserved in a chemical reaction
13H O H2OIs mass conserved in this equation?NO!Reactants:Products:2 H1 O2 H2 O
14How to Balance an equation Step 1. Place a box around all compoundsH O H2OStep 2. DO NOT make any changes to thecompounds inside each box!!!!!!
15How to Balance an equation Step 3. Place coefficients in front of eachbox to show conservation of mass.Everything inside the box will be multipliedby this number.H O H2O2Products:Reactants:4 H2 O2 H2 O
16How to Balance an equation Step 3. Place coefficients in front of eachbox to show conservation of mass.Everything inside the box will be multipliedby this number.2H O H2O2Products:Reactants:4 H2 O4 H2 O
17How to Balance an equation Step 4. Count the types of atoms on bothsides of the equation. The atoms on the reactantside must be the same as the atoms on theproduct side2H O H2O2Products:=Reactants:4 H2 O4 H2 O
18Helpful Hints for balancing Balance one type of atom at a timeBalance atoms that appear only once on each side of the equation firstBalance oxygen and hydrogen lastIt is an iterative process. Be Patient!
20Unknown reactants or products Since mass is always conserved, this principle can be used to find unknown parts of a chemical reactionCount the atoms on both sides of the equation and determine what atoms are missing from one side……
21Unknown reactants or products 2 Na + 2H2O X NaOHReactants:Products:2 NaH2 O2 Na2 H2 OX must be H2
22Unknown reactants or products 2 Na + 2H2O H NaOHReactants:Products:2 NaH2 O2 Na2 H2 OX must be H2
23Finding Missing MassIn a similar way to finding missing compounds, missing mass can also be found since mass is always conserved.
24Given the following balanced equation: 2 KClO KCl O2If 103 g of KClO3 decomposed to form 62.7 g of KCl,how many grams of oxygen gas are formed?
252 KClO KCl O2103 g = g x103 g – 62.7 g = x40.3 g = x