8.1 What Is a Chemical Reaction? Chemical reaction: One or more substance(s) are converted into new substances. What are… Reactants Products

8.2 Reactants Transformed into Products? Consider the reaction: H2 + I2  2HI What happens during a chemical reaction?

8.3 Balancing Chemical Equations Balanced chemical reaction: reactants and products must have equal numbers of each type of atom…why? H2 + I2  HI

8.3 Balancing Chemical Equations What about 2H2 + 2I2  4HI? What about this:

8.2 Reactants Transformed into Products? Reaction between molecules: What must happen? Endothermic: Exothermic:

8.4 Types of Reactions Single-replacement reaction An element replaces different one in a compound: What do you know about the reactivity of Al? 2 Al + Fe2O3  Al2O3 + 2 Fe Double-replacement reaction Elements replace each other in two compounds: PCl3 + 3AgF  PF3(aq) + AgCl (s)

Decomposition reaction 8.4 Types of Reactions Decomposition reaction One compound breaks down to two or more substances 2HgO(s)  2Hg(l) + O2(g) Combination (aka addition/synthesis) H2(g) + I2(g)  2 HI(g)

8.4 Types of Reactions Combustion reaction Products are often (but not always) H2Oand CO2

8.5 Part 2: Precipitation Reactions Precipitation reaction (double replacement) Solid product forms from mixing two or more solutions The solid that forms is the precipitate: Ca(NO3)2(aq)+ 2NaF(aq)  2NaNO3(aq)+ CaF2(s) Why is one product a precipitate?

8.5 Solubility and Precipitation Reactions Dissociation This is what happens when compounds dissolve NaCl(aq) means the crystal dissociated into Na+(aq) and Cl-(aq) The ions are spread throughout the mixture!

8.5 Solubility and Precipitation Reactions Mass of a substance that dissolves in water at a particular temperature Some molecular compounds dissolve in water Polar molecules that are similar to water… Many ionic compounds dissolve in water

8.5 Solubility and Precipitation Reactions

8.5 Solubility and Precipitation Reactions Double Replacement...is there a precipitate? Pb(NO3) 2(aq) + NaI(aq)  PbI2 + NaNO3 -Balance the equation first and find out!

8.5 Solubility and Precipitation Reactions BALANCED Equation Pb(NO3) 2(aq) + 2NaI(aq)  PbI2(s) + 2NaNO3(aq) Is either product insoluble?(check rules) NaNO3 … PbI2 …

8.5 Ionic and Net Ionic Equations Full Equation Pb(NO3) 2(aq) + 2NaI(aq)  PbI2(s) + 2NaNO3(aq) Complete ionic equation… Net Ionic Equation…

8.5 Solubility and Precipitation Reactions A solution of sodium sulfate is combined with a solution of barium chloride. Does a precipitate form? Write equation and balance it Determine if one product is insoluble Write full ionic equation Write net ionic equation Identify the ppt.

8.6 Introduction to Acid−Base Reactions Substance that dissociates H+(aq) Examples:

8.6 Introduction to Acid−Base Reactions Substance that dissociates OH-(aq)

8.6 Introduction to Acid−Base Reactions Acid-base neutralization Acid + Base  a salt + water HCl(aq) + NaOH(aq)  NaCl(aq) + H2O(l)

8.6 Introduction to Acid−Base Reactions Determine the neutralization products of the reaction between chlorous acid and sodium hydroxide… Balance full equation Write full and net ionic equations