CHEMICAL REACTIONS. The process by which one or more substances are changed into one or more different substances

Transcription

1 CHEMICAL REACTIONS The process by which one or more substances are changed into one or more different substances

2 Equations Reactions are represented by a chemical equation Reactants Products Must have the same number and type of atoms on both sides of the equation

3 Synthesis Reactions Two reactants produce one product Examples: NH3 + HCl NH4Cl H2 + O2 H2O Ag + S Ag2S Al + Cl2 AlCl3

4 Decomposition One reactant produces two products Examples Ag2O Ag + O2 PCl5 PCl3 + Cl2 H2O2 H2O + O2 CuO Cu + O2

5 Single Displacement One element and one compound producing a different element and compound Examples Fe + H3(PO4) H2 + Fe3(PO4)2 H2 + CuO Cu + H2O Zn + HCl H2 + ZnCl2 Cl2 + KBr Br2 + KCl

6 Double Displacement Two compounds producing two different compounds Examples: Al(NO3)3 + NaOH Al(OH)3 + NaNO3 PbCl2 + Li2SO4 PbSO4 + LiCl ZnBr2 + AgNO3 Zn(NO3)2 + AgBr BaCl2 + KIO3 Ba(IO3)2 + KCl

7 Combustion A hydrocarbon reacts with oxygen to produce carbon dioxide and water Examples: CH 4 + O 2 CO 2 + H 2 O C 6 H 12 O 6 + O 2 CO 2 + H 2 O

8 Using words

9 Chemical Equations from Names magnesium and hydrogen chloride produce hydrogen and magnesium chloride calcium hydroxide and lithium chloride produce lithium hydroxide and calcium chloride decompose copper (II) oxide into copper and oxygen aluminum and iron (III) oxide produce iron and aluminum oxide combustion of butane (C4H10) in air to produce carbon dioxide and water

10 Predicting the Product

11 Predicting the Product - Rules 1. If hydrocarbon reacts with oxygen combustion reaction i. The products will be CO 2 and H 2 O. 2. If two elements or very simple molecules combine synthesis reaction. i. The products will be predictable using the rules of ionic bonding.

12 Predicting the Product More Rules 3. If starting with one compound decomposition reaction. i. The products will be very simple molecules, or some elements, or both. a. Remember the rules for metals and non-metals 4. If a pure element reacts with another compound (usually ionic) single displacement reaction. i. The pure element (cation) switches places with another element (cation) in the other compound.

13 Predicting the Product More Rules 5. If two ionic compounds combine double displacement reaction. i. Switch the cations and balance out the charges to figure out what will be made.

14 Predict the Product - Practice Magnesium and nitrogen Copper II oxide is decomposed into its elements Chlorine and potassium bromide Calcium hydroxide and hydrogen sulfate Iron (III) chloride and sodium hydroxide Methane is combusted in air

15 Solubility and Precipitates

16 Precipitate Precipitation is the formation of a solid in a solution or inside another solid during a chemical reaction the solid formed is called the precipitate

17 SOLUBILITY RULES All common salts of Group I elements and ammonium are soluble All common acetates and nitrates are soluble All binary compounds of Group 7 (other than F) with metals are soluble except those of silver, mercury I and lead

18 More Solubility Rules All sulfates are soluble except those of barium, strontium, calcium, silver, mercury I and lead Except for those in Rule 1, carbonates, hydroxides, oxides, sulfides and phosphates are insoluble

19 Precipitate Reaction General form: AB(aq) + CD(aq) CB(s) + AD(aq) Description: In a precipitation reaction two solutions are mixed together to produce an insoluble solid which is called the precipitate. This type of reaction is also called a double displacement reaction

20 A little more on Chemical Reactions

21 Physical States of Matter and Symbols All physical states are given at standard temperature and pressure for each chemical species. (aq) = aqueous solution (dissolved in water, from aqua or water). (l) = liquid (s) = insoluble solid or precipitate. (g) = gas

22 Precipitate Reactions General form: AB(aq) + CD(aq) CB(s) + AD(aq) Is a double displacement reaction!!

23 Examples Lead nitrate(aq) + Potassium iodide(aq) Lead iodide(s) + potassium nitrate(aq) Pb(NO 3 ) 2 (aq) + 2KI(aq) PbI 2 (s) + KNO 3 (aq) Silver nitrate(aq) + sodium chloride(aq) Silver chloride(s) + sodium nirate(aq) AgNO 3 (aq) + NaCl(aq) AgCl(s) + NaNO 3 (aq) Mercury(II) nitrate(aq) + Potassium iodide(aq) Mercury iodide(s) + Potassium nitrate Hg(NO 3 ) 2 (aq) + 2KI(aq) HgI 2 (s) + KNO 3 (aq) Barium chloride(aq) + Sodium sulfate(aq) Barium sulfate(s) + Sodium chloride(aq) BaCl 2 (aq) + Na 2 SO 4 (aq) BaSO 4 (s) + NaCl(aq) Copper sulfate(aq) + Sodium hydroxide(aq) Copper hydroxide(s) + Sodium sulfate(aq) CuSO 4 (aq) + 2NaOH(aq) Cu(OH) 2 (s) + Na 2 SO 4 (aq)

24 Net Ionic Equations

25 What are Net Ionic Equations? Equations that show only the soluble, strong electrolytes reacting (ions) and omit the spectator ions, which go through the reaction unchanged. Bare bones of the chemical reaction Usually take place in aqueous environments Ions separate in water into cations and anions

26 Net Ionic Equations in words 1. Write the (balanced!) molecular equation first Reaction products: swap cations and anion Predict solubility (using Solubility rules)

27 Net Ionic Equations in words 2. Write the complete ionic equation next (s) compounds don t ionize (aq) compounds do ionize ion subscripts in the molecular equation become coefficients in the complete ionic equation Ie (NO 3 ) 2 becomes 2(NO 3 )

28 Net Ionic Equations in words 3. Write the net ionic equation next cancel spectator ions The net ionic equation is a simplified form of the complete ionic equation

29 Net Ionic Equations Balanced Chemical Equation: Pb(NO 3 ) 2 (aq) + 2NaI (aq) PbI 2 (s) + 2NaNO 3 (aq) Complete Ionic Equation: Pb 2+ (aq) + 2NO 3 - (aq) + 2Na + (aq)+ 2I - (aq) PbI 2 (s) + 2Na + (aq) + 2NO 3 - (aq) Cancel the spectator ions that appear on both sides of the arrow Pb 2+ (aq) + 2NO 3 - (aq) + 2Na + (aq)+ 2I - (aq) PbI 2 (s) + 2Na + (aq) + 2NO 3 - (aq) Net Ionic Equation: Pb 2+ (aq) + 2I - (aq) PbI 2 (s)