Presentation on theme: "Objectives To learn more about some of the results of chemical reactions To learn to predict the solid that forms in a precipitation reaction To learn."— Presentation transcript:
1 ObjectivesTo learn more about some of the results of chemical reactionsTo learn to predict the solid that forms in a precipitation reactionTo learn to write molecular, complete ionic, and net ionic equations
2 A. Common Results of a Reaction Four common events accompany chemical reactions. These often occur when a reaction happensFormation of a solidFormation of waterFormation of a gasTransfer of electronsCan you give examples of each of these?
3 B. Precipitation Reactions What Happens When an Ionic Compound Dissolves in Water?H2ONaCl (s)NaCl (aq)But what does NaCl (aq) mean?Na+ and Cl- ions in water ?NaCl molecules in water ?Na and Cl atoms in water?
4 B. Precipitation Reactions What Happens When an Ionic Compound Dissolves inWater?The ions separate and move around independently – a strong electrolyte
5 B. A Reaction in Which a Solid Forms A reaction in which a solid is formed from a solution is called a precipitation reactionSolid = precipitate = insolubleWhen positive and negative ions form a precipitate the net charge of the precipitate is zeroPb(NO3)2 (aq) + 2NaI (aq)PbI2 (s) + 2NaNO3 (aq)
6 Stalactites in Yosemite Ca(HCO3)2(aq)→ CaCO3(s) +H2O(l) + CO2(aq)
8 B. Precipitation Reactions What Happens When Two Ionic Compounds Dissolve inWater?K2CrO4(aq) + Ba(NO3)2(aq) Products
9 B. Precipitation Reactions How to Decide What Products FormDetermine the possible products from the ions in the reactants.In our exampleK2CrO4(aq) + Ba(NO3)2(aq) ProductsThe possible ion combinations are
10 What are the potential products in the reactions between the following aqueous solutions? – Write balanced equations for eachNaOH + CaCl2CuBr2 + (NH4)2CO3K2SO4 + Fe(NO3)3
11 B. Precipitation Reactions How Would We Decide What Product Has Formed?What is most likely to be the yellow solid formed in the following reaction?K2CrO4(aq) + Ba(NO3)2(aq)The possible product combinations are KNO3 and BaCrO4KNO white solidBaCrO yellow solid
13 B. Precipitation Reactions Using Solubility RulesPredicting PrecipitatesSoluble solidInsoluble solid(Slightly soluble solid)Why are some compounds soluble and others not?
14 Solubility Rules – Are These Compounds Soluble or Insoluble? Barium NitratePotassium CarbonateSodium SulfateCopper (II) HydroxideMercury (I) ChlorideAmmonium PhosphateChromium (III) SulfideLead (II) Sulfate
15 B. Precipitation Reactions Let’s try some predictions: WOC P271 Q10
16 C. Describing Precipitation Reactions in Aqueous Solutions Three types of equations:Molecular (formula) equation complete formulas of all reactants and productsComplete ionic equation all strong electrolytes are shown as ionsNet ionic equation only those components of the solution that undergo a changeSpectator ion (those that remain unchanged) not shown in the net ionic equation
17 C. Describing Precipitation Reactions in Aqueous Solutions Molecular EquationPb(NO3)2 (aq) + 2NaI (aq)PbI2 (s) + 2NaNO3 (aq)Complete Ionic EquationPb2+(aq) + 2NO3-(aq) + 2Na+(aq) + 2I-(aq)PbI2(s) + 2Na+(aq) + 2NO3-(aq)
18 C. Describing Precipitation Reactions in Aqueous Solutions Net Ionic EquationPb2+(aq) + 2I-(aq) PbI2(s)What are the spectator ions in this reaction?A solution of sodium chloride in water reacts with aqueous silver nitrate to give a precipitate of silver chloride – write down the three equations that describe this reaction and identify the spectator ions(P272 Q14 – all three equations and identify spectators)