2Evidence of Chemical Change Changes in Energy (E)Release of E as heatRelease of E as lightProduction of soundReduction or increase of temperatureAbsorption or release of electrical EnergyFormation of new substancesFormation of a gasFormation of a precipitateChange in colorChange in odor
3Law of Conservation of Mass Same number of atoms on both In any physical or chemical reaction, mass is neither created nor destroyed; it is conserved!Reactants ProductsSame number of atoms on bothsides of the equation!
4Balancing Equations In every balanced equation each side of the equationhas the same number of atomsof each element
5Important stuff! Heat Pressure Temperature Catalyst Four abbreviations are used to indicate physical states of chemicals: shown as subscripts in the chemical equation(s) = solid(l) = liquid(g) = gas(aq)= aqueous solution (dissolved in water)Symbols over the arrow indicate the conditions of the reactionHeatPressureTemperatureCatalystReversible reaction
6Balance this equation… NaNO3 + CrCl3 NaCl + Cr(NO3)3 How would you “write” it?
7Combination Reaction or Synthesis Reaction Two or more simple substances react to form a more complicated oneA + B ABFe + S FeS
9Combination Reactions We can predict the products of ionic compounds by thinking about the charge!Al (s) + O2 (g) Cu (s) + S(s) Are there 2 possible products to this reactionsHow would we “say” these equations?
10Decomposition Reaction A decomposition reaction is the opposite of a composition reaction - a complex molecule breaks down to make simpler ones.AB A + B2 H2O 2 H2 + O2
16Single Replacement Reactions Easy to predict the products. Look at the ions… remember that a cation has to bond to an anion!!Don’t forget about diatomics!Zn(s) + H2SO4(aq) Na(s) + H2O OOPS! Did we balance them?
18Single Replacement Reactions Reactivity of a metal makes a difference!If a metal is more reactive than the metal it is displacing a rxn will occur. If the metal is less reactive than the metal it is displacing, a rxn will not occur.
19Metal ReactivityIncreases down a groupDecreases across a period
27Combustion ReactionsA combustion reaction is when oxygen combines with another compound or element producing energy.When hydrocarbons (C?H?) combust, water, carbon dioxide and energy are produced.C10H O2 10 CO2 + 4 H2O + EnergyCombustion of Naphthalene
28Combustion Reactions Combustion of propane: C3H8 + O2 Combustion of methane:CH4 + O2 Combustion of butene (this one is tricky!)C4H O2
38Types of Reaction Lab Synthesis: Mg + O2 Did the mass of the system change after the reaction took place?Did you detect the presence of ammonia gas?Endothermic or exothermic?Mass should be greater- MgOMg + N yields Mg3N2Mg3N2 + H2O yields Mg(OH)2 + NH3
39Types of Reaction Lab Decomposition CaCO3 What evidence indicates a chemical reaction.How do you know that carbon dioxide was formed?Endothermic or exothermic?
40Types of Reaction Lab Single Replacement Zn + HCl What evidence did you see?What was in the little tube– how do you know?Endothermic or exothermic?
41Types of Reaction Lab Double Replacement PbNO3 + KI What evidence did you see?Endothermic or exothermic?
42Work on classifying the types of reactions on your balancing WS. When you finish, you can start working on the back side of the Current Mole WS…. The front side should be complete!
43Warm Up Balance and classify the following reactions: Zn H2SO4 → H Zn(SO4)2CaCl NaNO3 → Ca(NO3) NaClC3H O2 → CO H2O
44You should have most of these WS done! Balancing equations WS– classified rxn type2. Mole Practice WS…Finish both of these… turn them in!Work on the Review!Due the beginning of class on Monday!Test after we go over the review!!
45Warm Up Balance and classify the following reactions: Na H2CO3 → H Na2CO32. NaF Ca(NO3)2 → NaNO CaF23. C5H O2 → CO H2O
46Warm Up- part 2Determine the molar mass of MgF2 Convert 5.7 g of magnesium fluoride to moles. Convert 6.3 g of magnesium fluoride to molecules.
47Warm Up Quiz Determine the molar mass of Na3PO4 How many moles in 10.6g of Na3PO4How many atoms in 0.50 mol Al?How many atoms in 3.6 g of carbon?
48Warm Up Balance and classify the following reactions: K H3PO4 → H K3PO43. CH O2 → CO H2O