Chemical Reactions

Formation of Solid Also called precipitate K2CrO4(aq)+ Ba(NO3)2(aq)-->forms a yellow solid substance How to identify the solid that forms in a precipitation reaction? know what happens when an ionic compounds dissolve in water Ba(NO3)2 ---- > Ba2+ NO3- K2CrO4 ----> K+ CrO42- substances that dissolves in water and produces separated ions are called strong electrolytes 11/10/2018

2K+(aq) + CrO42-(aq) + Ba2+ + 2NO3- How to decide what products form? K2CrO4 Ba(NO3)2 2K+(aq) + CrO42-(aq) + Ba2+ + 2NO3- How to decide what products form? Recall that a solid compound must have a zero net charge. The products must contain both anion and cation 11/10/2018

Example K2CrO4 Ba(NO3)2 2K+(aq) + CrO42-(aq) + Ba2+ + 2NO3 K+ and Ba+ could not combine CrO42- and NO3- could not combine  It should be a combination of positive and negative. Therefore; K2CrO4 + Ba(NO3)2 ---> BaCrO4 + 2KNO3 11/10/2018

Using Solubility Rules Soluble – dissolves in water Insoluble / slightly soluble dissolves tiny amounts that is undetectable to the naked eye 11/10/2018

Soluble compounds NO3- salts Na+,K+, NH4+ salts Cl-, Br-, I- salts except: Ag+, Hg22+ & Pb2+ SO42- salts except for Ba2+, Pb2+, Ca2+

Which is the solid substance? K2CrO4 + Ba(NO3)2 ---> BaCrO4 + KNO3

Examples: When silver nitrate is added to an aqueous solution of potassium chloride, a white solid forms. Identify the white solid and write the balanced equation for the reaction that occurs AgNO3(aq) + KCl(aq)---> white solid [Ag+ , NO3- ] + [K+ , Cl-] ----> products AgNO3 + KCl ----> AgCl + KNO3 white solid

Focus Question 2. Use the solubility rules in Table 8.1 to predict which of the following is soluble in water Potassium nitrate Zinc hydroxide Calcium carbonate  Ammonium chloride  Ans. S,I,I,S ( Note : S- soluble I- Insoluble)

Practice problems When an aqueous solution of barium nitrate is added to an aqueous solution of sodium sulfate, a white solid forms. Identify the white solid and write the balanced equation for the reaction that occurs

Answer Ba(NO3)2 + Na2SO4  BaSO4 + 2NaNO3 ( S) (aq)

Types of Chemical Reaction Synthesis/Combination Decomposition Single Replacement Double Displacement

Combination(Synthesis) 2 or more substances combine to form a more complex substance A + B ----> AB Ex: 2Ca + O2  2CaO 2SO2 + O2  2SO3

Decomposition One substance breaks down to form 2 or more substances AB -----> A + B Ex: HgO ----> Hg + O2 CaCO3 ----> CaO + CO2 NaHCO3---> Na2CO3 + H2O + CO2

Single Replacement A + BC ---> AC + B One element reacts by replacing another element in a compound Ex: Fe + CuSO4 ---> FeSO4 + Cu Mg + H2SO4 ---> MgSO4 + H2

Double Displacement Sometimes called ionic reaction Characterized by the exchange of ions AB + CD  AD + CB Ex KCl + Pb(NO3)2  PbCl2 + 2KNO3 K2CrO4 + Ba(NO3)2 ---> BaCrO4(s) + KNO3(l)