UNIT 9 - Chemical Equations and Reactions - PowerPoint Presentation

1. UNIT 9 - Chemical Equations and Reactions

2. Describing Chemical ReactionsChemical Reaction – process in which one or more substances are changed into one or more different substancesReactants – original substanceProducts – resulting substance Described by Chemical EquationsChemical equation – represents, with symbols and formulas, the identities and molar amounts of the reactants and products in a chemical reaction(NH4)2Cr2O7 (s)  N2 (g) + Cr2O3 (s) + 4H2O

3. https://www.youtube.com/watch?v=FOeH29hlHlU&t=1s

4. Physical IndicatorsTo know that a chemical reaction has taken place requires evidence that one or more substances have undergone a change in identity.Release of heat and lightColor changeProduction of gas (bubbles)Form a precipitateSolid that is produced as a result of a chemical reaction in solution

5. Writing Word EquationsAn equation in which the reactants and products in a chemical reaction are represented by wordsArrow  “react to yield” “yield” “produce” “form”Example: When methane burns it is combined with oxygen to produce carbon dioxide and water:Methane + oxygen  carbon dioxide + water

6. Practicing Word EquationSolid sodium reacts with a solution of aluminum chloride to produce aqueous sodium chloride and aluminum metal.Fluorine gas is bubbled through a solution of sodium bromide to produce bromine gas and aqueous sodium fluoride.Potassium chloride and water are produced from solutions of potassium hydroxide and hydrochloric acid.

7. EXIT SLIP1.) Solid mercury (II) oxide decomposes to produce liquid mercury metal and gaseous oxygen.2.) Solid zinc is added to an aqueous solution containing hydrochloric acid to produce gaseous hydrogen that bubbles out of solution and zinc (II) chloride that remains 3.) Ammonia gas (NH3) reacts with hydrogen chloride gas to form ammonium chloride gas.4.) Zinc metal reacts with copper (II) nitrate solution to form zinc (II) nitrate solution and copper solid.5.) Iron metal reacts with aqueous sulfuric acid to form iron (II) sulfate solution and hydrogen gas.

8. BellringerWhich substances are on the left hand side of the chemical equation?Which substances are on the right hand side?List 3 physical indicators.What does (aq) mean?NH3 + H2SO4  (NH4)2SO4 Is this correct? Why not? What law does it break? How can you fix it?

9. Chemical equations must satisfy the Law of Conservation of MassThe equation must contain the correct formulas for the reactants and productsThe law of conservation of mass must be satisfied Same number of atoms of each element must appear on each side of the correct chemical equationCoefficient – small whole number that appears in front of a formula in a chemical equation

10. Chemical equations MUST be balancedBalancing an equationRelative amounts of reactants and products represented in the equation must be adjusted so that the numbers and types of atoms are the same on both sides of the equationCarried out by inserting coefficients

11. HOW? __ CH4 (g) + __ O2 (g)  __ CO2 (g) + __ H2O (l) Count atoms of elements that only appear once on each side of the equation (usually leave H and O for last) C atoms: _______  _______ H atoms: _______  _______ O atoms: _______  _______Add any coefficient necessary to balance the atoms for each element individually C is balanced. Add a ______ in front of H2O Add a ______ in front of O2Count atoms to be sure the equation is balanced

12. Practice

13. Bellringer____ Na3PO4 + _____ CaCl2  ____ NaCl + ____ Ca3(PO4)2____ K + ____ Cl2  ____ KCl____ Al + ____ HCl  ____H2 + ____ AlCl3____ N2 + _____ F2  ____ NF3____ SO2 + ____ Li2Se  ____SSe2 + ____Li2O____ NH3 + ____ H2SO4  ____ (NH4)2SO4

14. Practice1.) Solutions of calcium nitrate and sodium hydroxide react to produce sodium nitrate in solution with solid calcium hydroxide. 2.) Copper (II) chloride is reacted with solid aluminum metal. Copper metal is produced as a solid and aluminum chloride is left in solution.

15. 5 types of Chemical ReactionsSynthesisDecompositionSingle-displacementDouble-displacementCombustion

16. SynthesisTwo or more substances combine to form a new compound:A+ X  AXA and X can be elements or compounds; AX is compoundEx: 2Mg(s) + O2(g)  2MgO(s)

17. Synthesis PracticeNa + Cl2 Al(s) + O2 

18. DecompositionA single compound undergoes a reaction that produces two or more simpler substances:AX  A + XA and X can be elements or compounds; AX is compoundEx: CaCO3(s)  CaO(s) + CO2(g)I will always give you the products for decomposition

19. Combustion ReactionA substance combines with oxygen, releasing a large amount of light and heat (always results in production of carbon dioxide and water vapor)C3H8(g) + 5O2(g)  3CO2(g)+ 4H2O(g)

20. Combustion Reaction PracticeC5H8 + O2 The combustion of octane.

21. Bell RingerSolid potassium reacts with nitrogen gasCombustion of ethaneC4H10(g) + O2(g) →Copper (II) reacts with iodine

22. Single Displacement ReactionOne element replaces a similar element in a compound:A + BX  AX + B OR Y + BX  BY + XA, B, X and Y are elements; AX, BX and BY are compoundsRule of thumb: cation will replace cation or anion will replace anion

23. Single Displacement Reaction ExamplesDisplacement of Metal with another Metal:2Al(s) + 3Pb(NO3)2(aq)  3Pb(s) + 2Al(NO3)3(aq)Displacement of Hydrogen in Water by a Metal:2Na(s) + 2H2O(l)  2NaOH(aq) + H2(g)Displacement of Halogens:Cl2(g) + 2KBr(aq)  2KCl(aq) + Br2(l)

24. Activity Series of ElementsWhat is it?A list of elements organized according to the ease with which the elements undergo certain chemical reactionsHow does it help?Helps you determine what substances will displace others in chemical reactionsUsed in single displacement reactions

25. Activity Series of Elements2Al + 3ZnCl2  3Zn + 2AlCl3Al is more reactive than Zn (higher on the activity series), so Al can replace ZnCo + 2NaCL  no reactionCo is less reactive than Na (lower on the activity series), so it can not replace NaCd + Pb(NO3)2 Cu + HCl 

26. Single Displacement PracticeCa + H2O KI + Br2 H2 + ZnCl Cu + HCl 

27. BELLRINGERTell the type of reaction and predict the products:Ca (s) + N2 (g)  Ti4+(s) + O2 (g)  KI + Br2 H2 + ZnCl What type of reaction is the following:NH4OH(aq)  NH3(g) + H2O(l)

28. Double Displacement ReactionThe ions of two compounds exchange places in an aqueous solution to form two new compoundsAX + BY  AY + BX A, B, X and Y are ions; AY, BX are ionic compoundsRule of thumb: The cation and the anion of both compounds will switch

29. Double Displacement Reaction ExamplesFormation of precipitate:2KI(aq) + Pb(NO3)2(aq)  PbI2(s) + 2KNO3(aq) Formation of a GasFeS(s) + 2HCl(aq)  H2S(g) + FeCl2(aq)Formation of water:HCl(aq) + NaOH(aq)  NaCl(aq) + H2O(l)As you can see in all examples the _________ and the ________ switch places

30. Double Displacement PracticeAgNO3 + NaCl FeS + HCl H2SO4 + KOH 

31. Type of Reactions ReviewClassify type of reactionN2 + 3H2  2NH32Li + 2H2O 2LiOH + H22NaNO3  2NaNO2 + O22C6H14 + 19O2  12 CO2 + 14H2O

32. Predicting Products PracticePredict the products, balance the equation and state the type of reaction:Copper (II) Nitrate reacts with sodium hydroxideFluorine gas reacts with silver (II) iodideAmmonium carbonate reacts with potassium nitrateSilver (II) reacts with lithium acetateCalcium reacts with bromine gasManganese (III) reacts with water

33. Net Ionic EquationsNet ionic equation: includes only those compounds and ions that undergo a chemical change in a reaction in an aqueous solutionStep 1: Convert chemical equation into a complete ionic equation All soluble ionic compounds (aq) are shown as dissociated ionsThe precipitates are shown as solidsEx: NaCl(aq) + AgNO3(aq) ---> AgCl(s) + NaNO3(aq) Complete Ionic Equation: Na+(aq) + Cl¯(aq) + Ag+(aq) + NO3¯(aq) ---> AgCl(s) + Na+(aq) + NO3¯(aq)

34. Net Ionic EquationsSpectator Ions: ions that do not take part in a chemical reaction and are found in solution before and after reactionStep 2: Cross out all spectator ionsEx: NaCl(aq) + AgNO3(aq) ---> AgCl(s) + NaNO3(aq) Na+(aq) + Cl¯(aq) + Ag+(aq) + NO3¯(aq) ---> AgCl(s) + Na+(aq) + NO3¯(aq) Net Ionic Equation: Cl¯(aq) + Ag+(aq) ---> AgCl(s)

35. Solubility RulesSoluble – ability of a compound to dissolve in a liquid solution

36. Net Ionic Equation ExamplesPb(NO3)2(aq) + Na2S(aq) ---> Complete Ionic Eq:Net Ionic Eq:ammonium phosphate + calcium chloride ---> Complete Ionic Eq:Net Ionic Eq:

37. Net Ionic Equation Practice – write complete ionic equation and the net ionic equation. Include coefficients, physical states and charges.A solution of aluminum bromide reacts with a solution of sodium hydroxide to form the precipitate aluminum hydroxide and aqueous sodium bromide.Aqueous copper (II) nitrate reacts with aqueous potassium carbonate, forming solid copper (II) carbonate and aqueous potassium nitrate.

38. Write complete and net ionic equationsA solution of barium chloride reacts with a solution of magnesium sulfate, to form the precipitate barium sulfate and aqueous magnesium chloride.Aqueous potassium sulfide reacts with a solution of cadmium (II) chloride, to form solid cadmium sulfide and aqueous potassium chloride.

39. Write word and formula equations (be sure to include physical states):Solid sodium oxide is added to water at room temperatures and forms sodium hydroxide.Word equation:Formula equation:Balanced formula equation:

40. Word Equation Practice (be sure to include physical states):Solid aluminum carbide, Al4C3 reacts with water to produce methane gas and solid aluminum hydroxide.Word equation:Formula equation:Balanced formula equation:

41. Word Equation Practice (be sure to include physical states):The combustion of octane.Word equation:Formula equation:Balanced formula equation: