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Las Positas College Chem 30A, 31 JB—6/17/02 WORKSHEET: Net Ionic Equations The key to writing correct net ionic equations is in knowing which substances to rewrite as ions and which substances to leave unchanged. Strong electrolytes exist in solution as ions and must always be written as ions for reactions in solution Strong Electrolytes: strong acids strong bases soluble salts Weak and non electrolytes exist predominantly as molecules or formula units in solution and must never be broken up when writing equations for reactions in solution. Weak Electrolytes: weak acids weak basess Non Electrolytes: insoluble salts and bases gases metals diatomic molecules all others not described above Decision Tree Practice: Identify each of the following substances as strong acid, weak acid, strong base, weak base, insoluble base, soluble salt, insoluble salt, molecular liquid, molecular gas, or insoluble element. Then write each substance as ions or not as ions in accordance with the decision tree. Ba(OH)2 CuCl2 NH3 H2SO4 H2 KCl HC2H3O2 Cu(NO3)2 BaSO4 Pb(NO3)2 Pb(NO2)2 H2O AgBr MgBr2 MgCO3 CuS CO2 HBr HF Al H3PO4 H2S LiHCO3 Fe(OH)3 CaSO4 Fe(C2H3O2)2 K2SO4 HNO3 H2CO3 ZnS NOTE: When H2CO3, H2SO3 or NH4OH are formed as products, they do break down, though not into ions. They break down into H2O and a gaseous substance. For each of the following, write the molecular equation (balanced, of course), the total ionic equation (still balanced), and the net ionic equation (also balanced). If examination of the total ionic equation reveals that there is no net reaction, then for the net ionic equation write the words “No Reaction.” 1. Aluminum metal is added to nitric acid solution. (single replacement) 2. A lead (II) nitrate solution is added to a calcium acetate solution. (double replacement) 3. A sulfuric acid solution is added to a solution of potassium hydrogen carbonate. (double replacement) 4. A barium nitrate solution is added to a sodium sulfate solution. (double replacement) 5. A sodium hydroxide solution is added to a phosphoric acid solution. Assume that 2 of the hydrogens in phosphoric acid react. Las Positas College Chemistry 30A, 31 JB—7/30/01 DECISION TREE: Should a formula be written as ions? Is the substance an acid (formula begins with H), a base (contains hydroxide ion), a salt (cation anion) or other? If it is an acid, go to A. If it is a base, go to B. If it is a salt, go to S. If it is an other, do not write it as ions. Example: Zn stays Zn (Note: There are three substances that decompose yielding gases when formed in chemical reactions: H2CO3, H2SO3 and NH4OH.) A. Is it a strong acid: H2SO4(aq), HClO4(aq), HNO3(aq), HCl(aq), HBr(aq), or HI(aq)? If yes, write it as ions. Example: H2SO4(aq) becomes 2 H+ + SO42If no, do not write it as ions. Example: HNO2(aq) stays HNO2 B. Is it a strong base: NaOH, LiOH, KOH, Ba(OH)2, or Ca(OH)2? If yes, write it as ions. Example: NaOH becomes Na+ + OHIf no, do not write it as ions. Example: Fe(OH)3 stays Fe(OH)3 (Note: Most hydroxides not listed above are weak or nonelectrolytes because they are insoluble in water—always check this out when writing net ionic equations.) S. Is it a soluble salt? Consult a table of solubilities. If soluble, write it as ions. Example: MgCl2 becomes Mg2+ + 2 Cl- If not soluble, do not write it as ions. Example: AgCl stays AgCl(s) © Adrian Dingle’s Chemistry Pages 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012. All rights reserved. These materials may NOT be copied or redistributed in any way, except for individual class instruction. Revised August 2011 AP WORKSHEET 12a: ANSWERS 1. A solution of potassium permanganate is added to a solution of conc. hydrochloric acid. 2MnO4- + 16H+ + 10Cl- 8H2O + 5Cl2 + 2Mn2+ ANSWER: Chloride ions lose electrons 2. A solution containing iodide ions is added to a solution containing iron (III) ions. 2I- + 2Fe3+ 2Fe2+ + I2 ANSWER: Fluorine since it most readily accepts electrons 3. Phosphorous trichloride is added to water. PCl3 + 3H2O H3PO3 + 3H+ + 3ClANSWER: Less than 7 since acids are formed 4. Lithium metal is burned in air. 4Li + O2 2Li2O 0 ANSWER: Li Li + 5. A solution of potassium dichromate is added to an acidified solution of sodium sulfite. Cr2O72- + 8H+ + 3SO32- 3SO42- + 4H2O + 2Cr3+ ANSWER: Orange Cr 6+ forms green Cr 3+ 6. A solution of tin (II) sulfate is added to a solution of iron (III) sulfate. Sn2+ + 2Fe3+ 2Fe2+ + Sn4+ ANSWER: Brown Fe 3+ forms green Fe 2+ 7. A solution of calcium hydroxide is added to a solution of magnesium chloride. Mg2+ + 2OH- Mg(OH)2 ANSWER: Calcium and chloride ions 8. Propane is burned completely in air. C3H8 + 5O2 3CO2 + 4H2O ANSWER: Alkanes 9. Manganese (IV) oxide is added to a solution of hydrobromic acid. MnO2 + 4H+ + 2Br- Br2 + 2H2O + Mn2+ 0 ANSWER: [Ar]4s 3d 5 10. Small chunks of solid sodium are added to water. 2Na + 2H2O 2Na+ + 2OH- + H2 ANSWER: The sodium would float on the surface with effervescence. The gas may ignite C:\Users\Adrian\Dropbox\ADCP\apwsheet12aanswers.doc Page 1 of 2 © Adrian Dingle’s Chemistry Pages 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012. All rights reserved. These materials may NOT be copied or redistributed in any way, except for individual class instruction. Revised August 2011 11. A solution containing tetramminecadmium(II) ions is treated with dilute acid. [Cd(NH3)4]2+ + 4H+ Cd2+ + 4NH4+ ANSWER: NH3 12. Calcium metal is added to a dilute solution of hydrochloric acid. Ca + 2H+ Ca2+ + H2 ANSWER: Squeaky pop noise with a lighted splint 13. Equimolar amounts of solutions of sodium dihydrogenphosphate and sodium hydroxide are mixed. H2PO4- + OH- H2O + HPO423- ANSWER: PO4 14. Solid calcium oxide is exposed to a stream of carbon dioxide gas. CaO + CO2 CaCO3 ANSWER: Bubbles of CO2 gas as the carbonate reacts with the acid 15. Magnesium turnings are added to a solution of iron (III) chloride. Mg + 2Fe3+ Mg2+ + 2Fe2+ ANSWER: Mg loses electrons 16. Chlorine gas is bubbled into a solution of sodium bromide. Cl2 + 2Br- Br2 + 2ClANSWER: Chlorine gas gains electrons 17. Solid zinc strips are added to a solution of copper (II) sulfate. Zn + Cu2+ Cu + Zn2+ ANSWER: Zn 18. Solid Lithium oxide is added to water. Li2O + H2O 2Li+ + 2OHANSWER: Alkali metals 19. Ethene is exposed to a stream of chlorine gas. C2H4 + Cl2 C2H4Cl2 ANSWER: Addition 20. Solutions of silver nitrate and sodium chromate are mixed. 2Ag+ + CrO42- Ag2CrO4 ANSWER: Precipitation and double displacement C:\Users\Adrian\Dropbox\ADCP\apwsheet12aanswers.doc Page 2 of 2 None are “no reaction” Write the balanced, net ionic equation, i.e. show significantly ionized species as separate ions and cancel out spectators Do NOT include state symbols Î Î C:\Users\Adrian\Dropbox\ADCP\apwsheet12a.doc What is the change in oxidation state of the Li? 4. Lithium metal is burned in air. What would be the pH of the resulting solution? Explain. 3. Phosphorous trichloride is added to water. Which halogen is the best oxidizing agent? Explain. Î 2. A solution containing iodide ions is added to a solution containing iron(III) ions. Which substance is oxidized in the reaction? Î Page 1 of 4 1. A solution of potassium permanganate is added to a solution of conc. hydrochloric acid. x x x Write balanced, net ionic equations and answer the questions for the following, noting that; Î C:\Users\Adrian\Dropbox\ADCP\apwsheet12a.doc What might one observe in this reaction? Î 10. Small chunks of solid sodium are added to water. What is the electronic structure of the manganese product? Î 9. Manganese(IV) oxide is added to a solution of hydrobromic acid. Page 2 of 4 Which homologous series (family) of organic compounds does propane belong to? 8. Propane is burned completely in air. What are the spectator ions in this reaction? Î 7. A solution of calcium hydroxide is added to a solution of magnesium chloride. What color change might one expect to observe? Î 6. A solution of tin (II) sulfate is added to a solution of iron(III) sulfate. What color change might one expect to observe? Î 5. A solution of potassium dichromate is added to an acidified solution of sodium sulfite. Revised August 2011 Revised August 2011 AP WORKSHEET 12a: Net Ionic Equation Writing I © Adrian Dingle’s Chemistry Pages 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012. All rights reserved. These materials may NOT be copied or redistributed in any way, except for individual class instruction. © Adrian Dingle’s Chemistry Pages 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012. All rights reserved. These materials may NOT be copied or redistributed in any way, except for individual class instruction. C:\Users\Adrian\Dropbox\ADCP\apwsheet12a.doc Which substance is reduced? Î 16. Chlorine gas is bubbled into a solution of sodium bromide. Which substance is oxidized in this reaction? Î 15. Magnesium turnings are added to a solution of iron(III) chloride. If the product were exposed to an acidic environment, what would be observed? Î 14. Solid calcium oxide is exposed to a stream of carbon dioxide gas. Page 3 of 4 If excess hydroxide ions had been added instead, suggest the formula of an ion that may have been produced? Î C:\Users\Adrian\Dropbox\ADCP\apwsheet12a.doc Categorize this reaction in two ways? Î 20. Solutions of silver nitrate and sodium chromate are mixed. Î 19. Ethene is exposed to a stream of chlorine gas. 13. Equimolar amounts of solutions of sodium dihydrogenphosphate and sodium hydroxide are mixed. What type of reaction is this? What is the name of the group of elements that Lithium is a member of? Describe a simple laboratory test for the gas produced in this reaction? Î 18. Solid Lithium oxide is added to water. 12. Calcium metal is added to a dilute solution of hydrochloric acid. Î Which substance is the reducing agent? Which substance acts as the base in this reaction? Page 4 of 4 17. Solid zinc strips are added to a solution of copper(II) sulfate. 11. A solution containing tetramminecadmium(II) ions is treated with dilute acid. Î Revised August 2011 Revised August 2011 Î © Adrian Dingle’s Chemistry Pages 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012. All rights reserved. These materials may NOT be copied or redistributed in any way, except for individual class instruction. © Adrian Dingle’s Chemistry Pages 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012. All rights reserved. These materials may NOT be copied or redistributed in any way, except for individual class instruction. © Adrian Dingle’s Chemistry Pages 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012. All rights reserved. These materials may NOT be copied or redistributed in any way, except for individual class instruction. Revised August 2011 AP WORKSHEET 12c: ANSWERS 1. A solution of sodium hydroxide reacts with a solution of hydrochloric acid. H+ + OH- H2O ANSWER: Sodium and chloride ions 2. A solution of potassium thiocyanate is added to a solution of iron(III) sulfate. SCN- + Fe3+ [FeSCN]2+ ANSWER: None, Fe 3+ on both sides of the equation 3. Dinitrogen trioxide is added to water. N2O3 + H2O 2HNO2 ANSWER: Nitrous acid 4. Potassium metal is burned in air. 4K + O2 2K2O ANSWER: Potassium changes from 0 to +1 by losing electrons 5. A solution of acidified sodium dichromate has a solution of iron (II) ions added to it. 6Fe2+ + Cr2O72- + 14H+ 2Cr3+ + 7H2O + 6Fe3+ 2+ ANSWER: Fe 3+ Fe +e - 6. Solutions of zinc chloride and potassium phosphate are mixed. 3Zn2+ + 2PO43- Zn3(PO4)2 ANSWER: A lilac color since potassium ions are in solution 7. Magnesium metal is heated strongly in a stream of nitrogen gas. 3Mg + N2 Mg3N2 ANSWER: -3 8. A solution of acidified potassium permanganate is added to a solution of tin (II) ions. 5Sn2+ + 2MnO4- + 16H+ 5Sn4+ + 2Mn2+ + 8H2O ANSWER: REDOX, electrons are transferred 9. Ethene is reacted with steam. C2H4 + H2O C2H5OH ANSWER: Alcohols 10. Gaseous hydrogen iodide is dissolved in water. HI + H2O H3O+ + I+ ANSWER: Water is a base since it accepts H ions C:\Documents and Settings\AdrianD\My Documents\Dropbox\ADCP\apwsheet12canswers.doc Page 1 of 2 © Adrian Dingle’s Chemistry Pages 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012. All rights reserved. These materials may NOT be copied or redistributed in any way, except for individual class instruction. Revised August 2011 11. Chlorine gas is bubbled into cold, dilute sodium hydroxide solution. Cl2 + 2OH- ClO- + Cl- + H2O ANSWER: Chlorine changes from 0 to +1 AND -1 12. Sulfur trioxide is bubbled into water. SO3 + H2O H+ + HSO4ANSWER: It can acts as an acid by donating H + 13. Sodium metal is heated in a stream of chlorine gas. 2Na + Cl2 2NaCl ANSWER: REDOX/Composition/Synthesis 14. Solid magnesium carbonate is heated strongly. MgCO3 MgO + CO2 ANSWER: Decomposition 15. Pieces of magnesium metal are added to a solution of copper (II) sulfate. Cu2+ + Mg Mg2+ + Cu ANSWER: Blue (Cu 2+ ions) changes to a colorless solution of Mg 2+ 16. Acidified hydrogen peroxide is added to a solution containing iodide ions. 2I- + 2H+ + H2O2 2H2O + I2 ANSWER: London dispersion forces 17. Dilute nitric acid is added to copper(II) sulfide. 3CuS + 8H+ + 2NO3- 2NO + 4H2O + 3Cu2+ + 3S ANSWER: 2- to 0 18. Magnesium oxide has sulfur trioxide gas passed over it. MgO + SO3 MgSO4 ANSWER: One 19. Propyne is exposed to bromine. C3H4 + 2Br2 C3H4Br4 ANSWER: 6 sigma, 2 pi 20. A solution of barium chloride is added to a solution of potassium sulfate. Ba2+ + SO42- BaSO4 ANSWER: A white ppt of BaSO4 C:\Documents and Settings\AdrianD\My Documents\Dropbox\ADCP\apwsheet12canswers.doc Page 2 of 2 Î Î C:\Documents and Settings\AdrianD\My Documents\Dropbox\ADCP\apwsheet12c.doc Which species is oxidized in the reaction? 4. Potassium metal is burned in air. What is the name of the product? 3. Dinitrogen trioxide is added to water. What is the change in oxidation state of the Fe species? Î 2. A solution of potassium thiocyanate is added to a solution of iron(III) sulfate. What are the spectator ions in this reaction? Î 1. A solution of sodium hydroxide reacts with a solution of hydrochloric acid. Page 1 of 4 None are “no reaction” Write the balanced, net ionic equation, i.e. show significantly ionized species as separate ions and cancel out spectators Do NOT include state symbols Write balanced, net ionic equations and answer the questions for the following, noting that; Î Î C:\Documents and Settings\AdrianD\My Documents\Dropbox\ADCP\apwsheet12c.doc What is the role of water in this reaction? Explain Î 10. Gaseous hydrogen iodide is dissolved in water. To which homologous series (family) does the organic product belong? 9. Ethene is reacted with steam.. What type of reaction is occurring here? Explain Î 8. A solution of acidified potassium permanganate is added to a solution of tin(II) ions. What is the final oxidation state of N? 7. Magnesium metal is heated strongly in a stream of nitrogen gas. Page 2 of 4 If a flame test were conducted on the result solution, what might one expect to observe? Î 6. Solutions of zinc chloride and potassium phosphate are mixed. Write a half equation to show the change in Fe in this reaction? Î 5. A solution of acidified sodium dichromate has a solution of iron(II) ions added to it. Revised August 2011 Revised August 2011 AP WORKSHEET 12c: Net Ionic Equation Writing III © Adrian Dingle’s Chemistry Pages 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012. All rights reserved. These materials may NOT be copied or redistributed in any way, except for individual class instruction. © Adrian Dingle’s Chemistry Pages 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012. All rights reserved. These materials may NOT be copied or redistributed in any way, except for individual class instruction. C:\Documents and Settings\AdrianD\My Documents\Dropbox\ADCP\apwsheet12c.doc What type of bonding exists between molecules of iodine? Î 16. Acidified hydrogen peroxide is added to a solution containing iodide ions. What color change might one expect to observe? Î 15. Pieces of magnesium metal are added to a solution of copper(II) sulfate. What type of reaction is this? Î C:\Documents and Settings\AdrianD\My Documents\Dropbox\ADCP\apwsheet12c.doc What color change might be observed? 20. A solution of barium chloride is added to a solution of potassium sulfate. 14. Solid magnesium carbonate is heated strongly. Î How many sigma and pi bonds in Propyne? What type of reaction is this? Î 19. Propyne is exposed to bromine. 13. Sodium metal is heated in a stream of chlorine gas. Î The Lewis diagram for sulfite has how many lone pairs around the central atom? Explain the role of the product in this reaction? Î 18. Magnesium oxide has sulfur trioxide gas passed over it. 12. Sulfur trioxide is bubbled into water. Î What is the change in oxidation state of sulfur in this reaction? This reaction is classified as a disproportionation, why? Page 3 of 4 Page 4 of 4 17. Dilute nitric acid is added to copper(II) sulfide. 11. Chlorine gas is bubbled into cold, dilute sodium hydroxide solution. Î Revised August 2011 Revised August 2011 Î © Adrian Dingle’s Chemistry Pages 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012. All rights reserved. These materials may NOT be copied or redistributed in any way, except for individual class instruction. © Adrian Dingle’s Chemistry Pages 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012. All rights reserved. These materials may NOT be copied or redistributed in any way, except for individual class instruction. Chemistry Mr. Bennett Name_____________ NH3(aq) + HClO3(aq) NH4+(aq) + ClO3–(aq) HCN(aq) + CO32–(aq) HCO3–(aq) + CN–(aq) NH3(aq) + HF(aq) F- (aq) + NH4+(aq) CO32–(aq) + HClO3(aq) HCO3–(aq) + ClO3– HOCl (aq) + NH3 (aq) OCl- (aq) + NH4+ (aq) HF (aq) + CO32– (aq) F–(aq) + HCO3–(aq) NH3(aq) + HNO2(aq) NH4+(aq) + NO2–(aq) CO32–(aq) + HOCl(aq) HCO3–(aq) + OCl–(aq) NH3(aq) + HC2H3O2(aq) NH4+(aq) + C2H3O2– CO32–(aq) + HNO2(aq) HCO3–(aq) + NO2–(aq) HClO3(aq) + NH2(aq) NH4+(aq) + ClO2–(aq) CO32–(aq) + HC2H3O2(aq) HCO3–(aq) + C2H3O2–(aq) NH3(aq) + HBrO3(aq) NH4+(aq) + BrO3–(aq) CO32–(aq) + HClO3(aq) HCO3–(aq) + ClO3–(aq) NH3(aq) + HIO3(aq) NH4+(aq) + IO3–(aq) CO32–(aq) + HBrO3(aq) HCO3–(aq) + BrO3–(aq) Advanced Chemistry Mr. Bennett Name_________________ Date________ Predict the oxidation number of the underlined element. NaIO3 MnO LiH CoSO4 Sr(NO3)2 RaCl2 Hg(NO3)2 CaC2O4 NaNO3 Al(ClO3)3 HgF2 K2SO4 CoS SrI2 Fe(NO3)3 MgSiO3 NH4F Pb(CN)2 AgBr Ag2S MgH2 Ca3(PO4)2 H2SO4 Determine if the following reactions are redox reactions. If yes, then label the element that is oxidized, the element that is reduced, the oxidizing agent and the reducing agent. 1. (NH4)2Cr2O7 Cr2O3 + N2 + H2O 1. Ag2S + KCN KAg(CN)2 + K2S 2. NaHCO3 ---> Na2CO3 + CO2 + H2O 3. Au2S3 + H2 ---> Au + H2S 4. Fe2(C2O4)3 ---> FeC2O4 + CO2 5. ClO2 + H2O ---> HClO2 + HClO3 6. Ca3P2 + H2O ---> Ca(OH)2 + PH3 7. K2O + CO2 ---> K2CO3 8. As + NaOH ---> Na3AsO3 + H2 9. MgNH4PO4 ---> Mg2P2O7 + NH3 + H2O 10. MnO2 + HCl ---> MnCl2 + H2O + O2 11. Pb+6 + Na + C2H5Cl ---> Pb(C2H5)4 + NaCl 12. Ca(OH)2 + H3PO4 ---> CaHPO4 + H2O 13. Zn + NaOH + H2O ---> Na2Zn(OH)4 + H2 14. SrBr2 + (NH4)2CO3 ---> SrCO3 + NH4Br 15. Hg(OH)2 + H3PO4 ---> Hg3(PO4)2 + H2O 16. Ca3(PO4)2 + SiO2 + C ---> CaSiO3 + P4 + CO 17. I4O9 ---> I2O6 + I2 + O2 18. C2H3Cl + O2 ---> CO2 + H2O + HCl 19. (NH4)2Cr2O7 ---> NH3 + H2O + Cr2O3 + O2 Common Oxidizing and Reducing Agents You Should Memorize Oxidizing Agent Turns In To… Reducing Agent Turns In To… MnO4(in acid) MnO4(in neutral or basic) MnO2 (in acid) Cr2O72(in acid) HNO3 (conc.) HNO3 (dilute) H2SO4 (hot and conc.) Highly charged metal cations Free Halogens (Cl2, Br2, I2, F2) H2O2 (in acid) Mn2+ Free Halogens (Cl2, Br2, I2, F2) Metal cations Mn2+ Halide ions (Cl-, Br-, I-, F-) Free metals (eg. Zn) SO32- or SO2 Cr3+ NO2- NO3- NO2 Free halogens (in dilute basic) Free halogens (in conc. Basic) Lower charged metal cations H2O2 (in basic) S2O32- Hypohalite ions (XO-) + halide (X-) Halite ions (XO3-) H2 H+ usually in the form of water MnO2 NO SO2 Lower charged metal cations Halide ions (Cl-, Br-, I-, F-) H2O SO42- Highly charged metal cations O2 + H2O S4O62- Examples: Sulfur dioxide gas is bubbled through a solution of acidified potassium manganate (VII) (permanganate) - SO2 + MnO4 + H + 2- H2O + SO4 2+ + Mn Hydrogen peroxide is added to an acidified solution of potassium dichromate (VI) + H2O2 + H 2- + Cr2O7 Cr 3+ O2 + H2O Concentrated hydrochloric acid is added to solid manganese (IV) oxide H + + Cl - + MnO2 2+ Mn Cl2 + H2O Predicting Redox Reaction Products: Common Oxidizing Agents MnO41- in acidic solution MnO2 in acidic solution MnO41- in neutral or basic solution Cr2O72- in acidic solution HNO3, concentrated HNO3, dilute H2SO4, hot, concentrated Metallic ions (higher oxidation #) Free halogens Na2O2 HClO4 C2O42H2O2 Common Reducing Agents Halide ions Free metals Sulfite ions or SO2 Nitrite ions Free halogens, dilute basic solution Free halogens, conc. basic sol. Metallous ions (lower oxidation #) Products Formed Mn2+ Mn2+ MnO2(s) Cr3+ NO2 NO SO2 Metallous ions (lower oxidation #) Halide ions NaOH Cl1CO2 O2 Products Formed Free halogen Metal ions Sulfate ions Nitrate ions Hypohalite ions Halate ions Metallic ions (higher oxidation #) omplex Ion Formation These are usually formed from a transition metal surrounded by ligands (polar molecules or negative ions). As a "rule of thumb" you place twice the number of ligands around an ion as the charge on the ion... example: the dark blue Cu(NH3)42+ (ammonia is used as a test for Cu2+ ions), and Ag(NH3)2+. Memorize the common ligands. Ligands Names used in the ion H 2O aqua NH3 ammine OH- hydoxy - chloro Br- bromo CN- cyano Cl thiocyanato (bonded through sulphur) - SCN isothiocyanato (bonded through nitrogen) Watchout for: Alumninum also forms complex ions as do some post transitions metals. Ex: Al(H 2O)63+ The names are very impressive, but easy..the ions above are the tetraamminecopper(II) ion, the diamminesilver(I) ion, and hexaaquoaluminum(III) ion. Zn(OH)42- is the tetrahydroxyzinc(II) ion, the charge is the sum of the parts (2+)+4(-1)= -2. Acid-base reactions may change NH3 into NH4+ (or vice versa) which will alter its ability to act as a ligand. Visually, a precipitate may go back into solution as a complex ion is formed. For example, Cu 2+ + a little NH4OH will form the light blue precipitate, Cu(OH)2. With access ammonia, the complex, Cu(NH3)42+, forms. Keywords such as "excess" and "concentrated" of any solution may indicate complex ions. AgNO3 + HCl forms the white precipitate, AgCl. With excess, concentrated HCl, the complex ion, AgCl 2-, forms and the solution clears. The odd complex ion, FeSCN2+, shows up once in a while simply because it is commonly used in the CHEMStudy first-year equilibrium lab. Transitional metals, such as Iron, Zinc and Chromium, can form complex ions. Aluminum can form complex ions as well. AP WORKSHEET 03j: Types of Reaction Electrolytes & Non-electrolytes Indicate if you would expect the following compounds to be electrolytes or non-electrolytes when in aqueous solution (dissolved in water). In each case very briefly explain your answer. Use equations if appropriate. (6) (a) Sodium fluoride (b) Methanol (CH3OH, an alcohol similar to ethanol – NOT a hydroxide) (c) Strontium nitrate 2. Ionic concentrations Calculate the concentration of the ion indicated in each of the following solutions. The use of square brackets [ ] denotes concentration in mol L-1. (3) (a) [K+] in 0.238 M KNO3 (b) [Al3+] and [SO42-] in 0.080 M Al2(SO4)3 3. Precipitation reactions and net ionic equations Predict if a precipitation reaction will occur in each of the following cases. If it does, write the full, balanced equation AND the net ionic equation (including state symbols) to show the formation of the precipitate. If there is no reaction, say so, and indicate why. (9) (a) CuSO4(aq) + Na2CO3(aq) (b) HI(aq) + Zn(NO3)2(aq) (c) AgNO3(aq) + NaBr(aq) 4. Acids and bases & neutralization (a) Write a full, balanced equation for the reaction of aqueous sulfuric acid and aqueous cesium hydroxide to produce an aqueous salt and water assuming that sulfuric acid donates BOTH of its hydrogen ions. Include state symbols. (2) (b) Rewrite the equation in (a) showing all ions present with state symbols. (2) (c) Rewrite the equation in (b) removing any spectator ions (i.e. write the net ionic equation) with state symbols. (2) 5. Oxidation numbers What is the oxidation number of each of the underlined atoms in each of the following species? Think carefully about the rules that are being applied and write a very brief, simple explanation of your answer in each case. (8) (a) CaI2 (b) GeO2 (c) KO2 (d) NH3 6. REDOX and half equations For each of the following ionic solids, write a balanced overall equation to show their formation from their elements. Then write the two balanced half equations (one showing oxidation, one showing reduction) that show the formation of the individual ions involved. (9) (a) Magnesium sulfide OVERALL: OXIDATION: REDUCTION: (b) Sodium bromide OVERALL: OXIDATION: REDUCTION: (c) Aluminum chloride OVERALL: OXIDATION: REDUCTION: 7. Disproportionation (a) Consider the following reaction. 3Cl2 5Cl- + Cl5+ Write two balanced half equations (one oxidation, one reduction) to show the changes that the chlorine species undergoes. (4) OXIDATION: REDUCTION: (b) Is this reaction a disproportionation? Justify your answer. (2) 8. REDOX Titration calculations (a) Consider the following half equations. SO32- + H2O SO42- + 2H+ + 2e- MnO4- + 8H+ + 5e- Mn2+ + 4H2O Combine these two equations to obtain the overall reaction of sulfite ions with manganate (VII) ions. (2) (b) Use the equation you have written in (a) to calculate the volume of 0.277 M manganate (VII) ions that are required to react completely with 20.0 mL of 0.451 M sulfite ions. (4) 9. Classification of chemical reactions By choosing two of the following reaction types from the list below, classify each of the following reactions in two ways. (12) Reaction types: precipitation, acid-base, REDOX (oxidation and reduction), single displacement, double displacement, combination, decomposition, combustion. (a) 2NaOH(aq) + CuSO4(aq) Na2SO4(aq) + Cu(OH)2(s) AND (b) HI(aq) + KOH(aq) KI(aq) + H2O(l) AND (c) C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(l) AND (d) 2HgO(s) 2Hg(l) + O2(g) AND (e) 4B(s) + 3O2(g) 2B2O3(s) AND (f) 2Al(s) + 6HNO3(aq) 2Al(NO3)3(aq) + 3H2(g) AND Question 1 3.47 g of the hydrated “double salt”, ammonium iron(II) sulfate hexahydrate, FeSO4(NH4)2SO4.6H2O was dissolved in 200. mL of water. 20.0 mL of the solution had some acid added to it and then it reacted completely with 12.6 mL of KMnO 4 solution. Calculate the concentration of the KMnO4 solution given the full REDOX equation below. 5Fe2+ + MnO4- + 8H+ 5Fe3+ + Mn2+ + 4H2O Question 2 When 25.0 mL of a solution of 0.200 M NaIO3 was added to acidified iodide ions, the iodine produced reacted with 20.3 mL of sodium thiosulfate (Na2S2O3). Calculate the concentration of sodium thiosulfate solution given the REDOX equations below. IO3- + 5I- + 6H+ 3I2 + 3H2O I2 + 2S2O32- 2I- + S4O62- Question 3 3.364 g of hydrated barium chloride BaCl2.xH2O was dissolved in water and made up to a total volume of 250.0 mL. 10.00 mL of this solution required 46.92 mL of 2.530 x 10 -2 M silver nitrate for complete reaction. Calculate the value of x in the formula of hydrated barium chloride, given the net ionic equation for precipitation below. Cl-(aq) + Ag+(aq) AgCl(s) Question 4 Calculate the concentration of 45.0 mL of a phosphoric acid solution that neutralized 20.8 mL of 0.532 M sodium hydroxide. Assume complete ionization of the acid. Question 5 If 0.664 g of an acid was required to neutralize 10.0 mL of 0.800 M NaOH, calculate the Molar Mass of the acid given it reacts with sodium hydroxide in a 1:2 ratio i.e., 1 ACID : 2 NaOH. Answers: 1. 0.0140 M 2. 1.48 M 3. 1 4. 0.0820 M 5. 166 g mol-1 Advanced Chemistry Mr. Bennett Name___________________ How many grams of Ba(OH)2 are contained in a 25.00 ml solution if 16.52 ml of 0.850 M HCl are required to completely neutralize the sample? 25.0 ml of 0.625 M HBr are mixed with 42.0 ml of 0.352 M NaOH. Find the final concentrations of all the ions present in the solution after the reaction occurs. Will the final solution be acidic, basic, or neutral? Explain. How many milliliters of 0.114 M H2SO4 solution provide the sulfuric acid required to react with the sodium hydroxide in 32.2 mL of 0.122 M NaOH according to the following equation? What volume of 0.337 M KOH provides enough solute to combine with the sulfuric acid in 18.6 mL of 0.156 M H2SO4? 5.1 Calculate the molarity of a solution containing, a) 23.9 g of NaCl dissolved in enough water to have 300 mL of solution b) 1.69 x 10-3 moles HCl in 12.0 mL of water 5.2 Describe how to prepare the following solutions. a) 450 mL of 0.500 M NaOH, from solid NaOH b) b) 900 mL of 1.00 M HCl, from 12.0 M HCl (concentrated HCl) 5.3 In the reaction, Mg + 2 HCl MgCl2 + H2 How many grams of magnesium will react with 250. mL of 0.500 M HCl? 5.4 How many grams of H2 will be produced when 1.00 g of Mg is added to a 250. mL sample of 0.500 M HCl? (Use the chemical reaction in 5.3.) 5.5 Calculate the volume of 0.360 M NaOH needed to neutralize 27.0 mL of 0.820M HCl. (Note: Write the chemical equation.) 5.6 Calculate the concentration of phosphoric acid produced when 2.00 g of P2O5 is added to 500 mL of distilled water. (Assume the final volume of the solution is 500 mL.) The important reaction is, How many moles of water remain unreacted? 5.7 Potassium dichromate in acidic solution is frequently used to determine the concentration of Fe(II) in solution. The equation which describes the reaction is: A solution of Cr2O72- is prepared by dissolving 6.425 g of K2Cr2O in 800.0 mL of water. (Assume no significant change in volume when the solution is prepared.) A total of 21.35 mL of this solution is required to reach the endpoint in a titration of a 250.0 mL sample containing Fe(II). Determine the concentration of Fe(II) in the solution. Originality is the one thing which unoriginal minds cannot feel the use of.--John Stuart Mill Unit 3 Practice Problems (with answers at end) It is in knowledge as in swimming: he who flounders and splashes on the surface makes more noise, and attracts more attention, than the pearl-diver who quietly dives in quest of treasures to the bottom.--Washington Irving Stoichiometry 1. Sodium reacts with water to form sodium hydroxide and hydrogen gas. How many grams of H2 can be produced from 11.5 g of sodium? Limiting reagents in stoichiometry 8. Aluminum and sulfuric acid react in a displacement reaction. If 5.0 g of Al and 45 g of sulfuric acid are used, what mass of hydrogen is collected? What is the limiting reagent? 9. A student prepares hydrogen bromide gas by reacting sodium bromide with phosphoric acid. Sodium phosphate is a by-product. If 24.3 g of sodium bromide is used with 100.0 g of phosphoric acid, how many grams of hydrogen bromide gas can be collected? What is the limiting reagent? 2. Hydrochloric acid reacts with calcium hydroxide to produce water and calcium chloride. How many grams of HCl are required to react with 10.0 g of calcium hydroxide? 3. Nitrogen reacts with hydrogen to make ammonia. How many grams of ammonia can be produced from 2.00 g of hydrogen? 4. Potassium chlorate decomposes when heated to give oxygen gas and potassium chloride. How many grams of oxygen gas can be obtained in this way starting with 1.226 g of KClO3? 5. Phosphorus trichloride is made when white phosphorus (P4) reacts with chlorine gas. How many grams of phosphorus are required to produce 5.49 g of phosphorus trichloride? 6. Ethene gas (C2H4) burns in oxygen to form carbon dioxide and water. How many grams of ethene must be burned to produce 200 g (to the nearest gram) of carbon dioxide? 7. Magnesium metal reacts with sulfuric acid in a displacement reaction. How many grams of hydrogen gas will be produced when 4.05 g of magnesium reacts completely? It's what we learn after we think we know it all that counts.--Kin Hubbard Molarity 10. Calculate the Molarity of a solution which contains 49.0 g of phosphoric acid in 2000.0 mL of solution. 11. Calculate the mass of solute in 1.5 L of solution which is 0.240 M in potassium dihydrogen phosphate. 12. How many grams of lead(II) acetate must be used to make 500.0 mL of a solution that is to contain 10 mg/mL of lead(II) acetate? What is the Molarity of the solution? 13. What volume (in Litres) of 0.100 M sodium chloride solution can be prepared from 117 g of the salt? 14. A test solution of aluminum nitrate must be made that is 20.0 g/L in the salt. If 1500.0 mL of the solution is desired, how many grams of the solute must be used? What is the Molarity of the solution? What is the Molarity of nitrate ion in the solution? Gravimetric analysis 15. What mass of AgBr is produced when100.0 mL of 0.150 M AgNO3 is added to 20.0 mL of 1.00 M NaBr? 20. A 50.00 mL sample of solution containing Fe2+ ions is titrated with a 0.0216 M KMnO4 solution. It required 20.62 mL of the KMnO4 solution to oxidize all of the Fe2+ to Fe3+ ions by the reaction: MnO4- + Fe2+ → Mn2+ + Fe3+ (unbalanced) 16. Aluminum can be determined gravimetrically by reaction with a solution of 8hydroxyquinoline (C9H7NO). The net ionic equation is: Al + 3 C9H7NO →Al(C9H6NO)3 + 3 H 3+ What was the concentration of the Fe2+ solution? + A mass of 0.1248 g of Al(C9H6NO)3 was obtained by precipitating all of the Al3+ from a solution prepared by dissolving 1.8571 g of a mineral. What is the mass percent of aluminum in the mineral sample? Next to being a great poet is the power of understanding one.--Longfellow Acid/Base titration 17. In standardizing an NaOH solution, a student found that 38.46 cm3 of the base neutralized exactly 32.33 cm3 of 0.1064 M HCl. Find the concentration (M) of the NaOH. 18. In titrating an H2SO4 solution, it was found that 23.66 cm3 of 0.2137 M NaOH would neutralize 22.04 cm3 of the acid. Find the concentration of the H2SO4. Redox titration 19. A solution of permanganate is standardized by titration with oxalic acid (H2C2O4). It required 28.97 mL of the permanganate solution to react completely with 0.1058 g of oxalic acid. The unbalanced reaction is: MnO4- + H2C2O4 → Mn2+ + CO2 (unbalanced) What is the Molarity of the permanganate solution? (H+) Answers: 1. 0.50 g 2. 9.86 g 3. 11 g 4. 0.480 g 5. 1.24 g 6. 63.8 g 7. 0.33 g 8. 0.58 g, Al 9. 19.1 g, NaBr 10. 0.250 M 11. 49 g 12. 5.0 g, 0.031 M 13. 20.0 L 14. 30.0 g, 0.0940 M, 0.282 M 15. 2.82 g 16. 0.3947% 17. 0.08944 M 18. 0.1147 M 19. 1.622 x 10-2 M 20. 4.45 x 10-2 M (H+) Advanced Chemistry Mr. Bennett Name______________ October 16, 2007 1. The iron content of iron ore can be determined by titration with standardized KMnO4 solution. The iron ore is dissolved in HCl, and all the iron is reduced to Fe+2 ions. The solution is then titrated with KMnO4 solution, producing Fe+3 and Mn+2 ions in acidic solution according the equation below. If it requires 41.95 ml of 0.0205 M KMnO4 to titrate a solution made from 0.6128 g of iron ore, what is the percentage of iron in the ore? MnO4-(aq) + 5 Fe+2(aq) + 8 H+(aq) 5 Fe+3(aq) + Mn+2(aq) + 4 H2O(l) 2. A 16.75 ml, 1.67 M CaCl2 solution is mixed with 38.62 ml of 0.759 M CaCl2 solution. Calculate the molarity of the Cl- ions in the final solution. Part I: Reactions Review your quiz Part II: Solve the following calculations; include your work, correct significant digits, and units with your answers. 1. A solution is made by dissolving 15.9 grams of HCl in 125.0 ml of 1.25 M LiOH. a. Is the final solution acidic, basic, or neutral? b. Calculate the molarity of all of the ions present after the reaction takes place. 2. What volume, in ml, of 0.475M LiCl is needed to precipitate all of the Pb+2 ions from 140.0 ml of a 0.325 M Pb(NO3)2 solution? 3. A solution is prepared by dissolving 47.5 grams of (NH4)2SO4 in enough water to make 750.0 ml of solution. A 75.5 ml sample of this solution is then diluted to 425.0 ml. What is the molarity of the NH4+ and SO4-2 ions in this final solution? 4. A sample containing only Lead (II) nitrate and Lead (II) acetate is dissolved and treated with NaCl. A 3.500 gram sample of the salt mixture produced 1.005 grams of PbCl2 as a precipitate. Calculate the percentage of Lead (II) in the original sample.