Chapter 8 Chemical Equations !Word Equation – the names of the substances are given inwords for you to interpret.Zinc plus Hydrochloric Acid yields Zinc chloride plus Hydrogen gas ! REACTANTS PRODUCTS
Interpreting chemical equations Al (OH)3 + 3HCl AlCl3 + 3 H2O Reacts To make And threeOne with 3 one FU of moleculesformula molecules aluminum of waterunit of of HCl chloridealuminumhydroxideSO WHAT DOES THIS MEAN????
Balanced Equations2Na + 2H2O 2NaOH + H2Because mass is neither lost nor gained in a chemicalreaction, all atoms of both substances must beaccounted for.
Steps For Balancing Chemical Equations1. Write a word equation for the reaction2. Write the correct formula for all the reactants and products3. Determine coefficients that make the equation balance ONLY CHANGE COEFFICIENTS, NEVER EVER CHANGE THE SUBSCRIPTS !!!!!!!!!!!!!!!!!!!!
Showing EnergyEndothermic Reactions 2H2O + Energy 2H2 + O2Exothermic Reactions 2H2 + O2 2H2O + Energy
Showing Phases in Chemical Reactions Substances may exist in the form of a solid liquid or gas Solid Phase: Definite volume and shape. Liquid Phase: Definite volume, but changes shape. Gaseous Phase: No definite volume or shape.Use a (s) for solid, (l) for liquid, (g) for gas and (aq) foraqueous solutions. Remember, aqueous means dissolved ina solution (usually water !)
Ions in water solutionWhen ionic substances dissolve in water their crystal latticestructure breaks up and they exist as IONS in water !NaCl yields Na + plus Cl -KCl yields K+ plus Cl-
Classifying chemical reactionsSynthesis reaction A + B yields ABIRON PLUS OXYGEN yields IRON (111) OXIDEDecomposition reaction AB yields A + BSingle Replacement A + BC yields B plus ACZinc + HCl yields Zinc Chloride + Hydrogen gas Double Replacement AB plus CD yields AD plus CB NaOH + Magnesium chloride yields ????????????
Tricks to rememberIn single replacement reactions the “thing” that is ALONEmust be more REACTIVE than the “thing” being replaced orno reaction will occur !! (see page 286)In double replacement reactions you must have aPRECIPITATE, GAS, OR WATER AS A PRODUCT INORDER FOR THE REACTION TO OCCUR !! (otherwise allreactants are water soluble.)
Ionic equations and spectators !• Ionic equations simply show what is happening to the ions taking part in a reaction.• Spectator ions are those which do not actually participate in the reaction.• See rules page 224 !
Predict the products of the reaction.Zinc + copper sulfate yields Zinc sulfate + copper Magnesium chloride plus NO REACTION! Iron yields Calcium chloride + Sodium Calcium carbonate carbonate yields precipitate + NaCl
Predict the productsFluorine + NaI Iodine + NaFHydrogen + Oxygen WATERKClO3 KCl + OxygenCH O + O Carbon dioxide + 6 12 6 2 water
Write the NET ionic equation which occurs when aqueous solutions of zinc chloride and potassium hydroxide react. ZnCl2 (aq) + 2 KOH (aq) Zn (OH)2(s) + 2 KCl(aq)Zn+2 + 2Cl-1 + 2K+ + 2OH- Zn(OH)2(s) + 2K+ + 2Cl- Zn+2 + 2OH- Zn(OH)2(s)
Predict the productsWhen K reacts with MgF 2 Mg + KF When Mg reacts with KF NO REACTION
Predict the productsNaOH + KClNaNO3+ KBrAmmonium Carbonate + Magnesium carbonate as precipitate andMagnesium Chloride ammonium ions and chloride ions as spectators
solubleDOUBLE REPLACMENT Terminology…. aqueous PRECIPITATESPECTATOR ION COMBUSTION SINGLE REPLACEMENT DECOMPOSITION COEFFICIENT Net ionic equation SYNTHESIS REACTION Activity series
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