Chem 111 study guide for exam 2 Naming will probably rear its ugly head again Ch3-4 Be able to do gram-mol-mol-gram calculations Be able to use theoretical and percent yield Be able to use limiting reagents to calculate theoretical yield Be able to calculate molarities of solutions Be able to calculate molarities of ions in solution Be able to calculate molarities using acid/base titrations Be able to calculate the concentrations of excess reactants in a chemical reaction Be able to write balanced reactions From given formulas From given names of compounds Be able to predict the products for precipitation and acid/base reactions From given formulas From given names of compounds Be able to identify reaction types, acid/base, precipitation, redox, combustion using the solubility rules Be able to identify which compound is the acid or base Be able to identify which element is being oxidized or reduced Be able to identify the oxidizing or reducing agent Be able to write molecular and net-ionic equations Ch6 Be able to use energy transformations and enthalpy to predict if a reaction is endothermic/exothermic Be able to calculate ΔH Using Hess’s Law Using heats of formation Possible question types 1. Balance the following chemical equations and indicate the type of reaction each is: (a) _____C8H18(g) + _____O2(g) _____CO2(g) + _____H2O(g) (b) _____HCl(aq) + _____Al(OH)3(aq) _____H2O(l) + _____AlCl3(aq) (c) _____K(s) + _____H2O(l) _____H2(g) + _____KOH(aq) 2. Name or give the formula of the following compounds P4O10 Cr2(SO4)3 Iron(III) hydrogen carbonate Aluminum sulfide Acetic acid 3. Sodium Silicate reacts with hydrofluoric acid as follows: Na2SiO3(s) + 8 HF(aq) H2SiF6(aq) + 2 NaF(aq) + 3 H2O(l) How many grams of H 2SiF6 can be produced from the complete reaction of 825 g of HF ? 4. Write balanced net ionic equations for the reactions that may occur when each of the following pairs is mixed: H2SO4 (aq) and BaCl2 (aq) (NH4)2 SO4 (aq) and NaCl(aq) Pb(NO3)2 (aq) and MgSO4 (aq) 5. The distance between Lexington and Morehead is 60 miles ( 1 mile = 1.6093 km, 1 gal = 3.7854 L ). Suppose your car gets 34 miles to the gallon of gasoline and that gasoline is pure octane, C 8H18 (density = 0.7033 g/mL). Write the equation for the combustion of octane. Hº for the combustion of octane is -5069 kJ/mol. How much heat will your car generate on the trip? 6. How many milliliters of 0.155 M HCl are needed neutralize completely 35.0 mL of 0.101 M Ba(OH)2 solution? 7. Consider the following balanced net ionic equation: 3SO32- (aq) + 2 CrO42- (aq) + 10 H+(aq) 3SO42- (aq) + 2 Cr3+ (aq) + 3H2O How many grams of Na2 CrO4 are theoretically required to completely oxidize 37.8 g of Na2SO3 8. What is meant by the term system in thermodynamics? Explain 9. Explain the difference between an electrolyte and a nonelectrolyte. 10. Silicon carbide, SiC, is commonly known as carborundum. This hard substance, which is used commercially as an abrasive, is made by heating SiO 2 and C to high temperatures: SiO2 (s) + 3C (s) SiC (s) + 2CO (g) How many grams of SiC can form when 3.00 g of SiO2 and 4.50 g of C are allowed to react? Which reactant is the limiting reagent? 11. How many milliliters of a stock solution of 12.0 M HCl would you have to use to prepare 250 mL of a 1.50 M HCl solution? 12. What is the difference between 0.150 mol NaCl and 0.150 M NaCl? 13. Consider the reaction between AgNO 3(s) and BaCl2(s): The heats of formation ( Hfo) are as follows: AgNO3 -124.4 kJ/mol BaCl2 - 858.6 kJ/mol AgCl -127.1 kJ/mol Ba(NO3)2 - 992.0 kJ/mol What is the enthalpy ( Ho) for the reaction? 14. Write balanced net ionic equations for reactions that occur when each of the following solutions are mixed. If no reaction occurs write no reaction. NaBr + KNO3 KCl + AgNO3 HCl + NaOH CaCl2 + K2CO3 15. In the following reaction: Cl2 (aq) + 2 NaI I2(aq) + NaCl(aq) identify the species being oxidized identify the species being reduced identify the oxidizing agent identify the reducing agent 16. A student prepared aspirin (C9H 8O4) from salicylic acid (C7H6O3 , FW = 132.118 g/mol) and acetic anhydride (C4H6O3 , FW = 102.088 g/mol) C7H6O3 + C4 H6O3 C9H8O4 + HC2H3 O2 How many grams of aspirin can be produced if the student reacted 1.50 g of salicylic acid with 2.00 g of acetic anhydride? If the student obtained 1.50 g of aspirin what is the percent yield for the aspirin synthesis? 17. Indicate the type of the following reactions as acid/base, redox, or precipitation (ppt): Fe(s) + O2(g) Fe2O 3(s) Type__________________ Na2SO4(aq) + MgBr 2(aq) NaBr(aq) + MgSO4 (s) Type__________________ HCl(aq) + Al(OH)3 (aq) H2O(l) + AlCl3(aq) Type__________________ Mg(s) + SiO2(s) MgO(s) + Si(s) Type__________________ 18. What is the concentration of sodium ion in a solution if 13.0 mg of NaCN is dissolved in 5.00 mL of water? Draw a microscopic picture of the NaCN dissolved in water (H 2O). 19. The combustion of one mole of benzene, C 6H6, in oxygen liberates 3268 kJ of heat. The products of the reaction are carbon dioxide and water. Write the thermochemical equation for the combustion of benzene. Is the reaction exothermic or endothermic? How much heat is given off when 8 moles of benzene are burned? 20. Given the standard heats of formation for the following compounds, calculate the ∆H° heat of reaction, for the following skeleton: Fe3 O4(s) + CO(g) → FeO(s) + CO2(g) ∆Hf° for Fe3O4 = –1118 kJ ∆Hf° for CO = –110.5 kJ ∆Hf° for FeO = –272 kJ ∆Hf° for CO2 = –393.5 kJ 21. Given that: 2 H2(g) + O2(g) → 2 H2O(l); ∆H° = –571 kJ/mol C3H4(g) + 4 O2(g)→ 3 CO2(g) + 2 H2 O(l); ∆H° = –1941 kJ/mol C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l); ∆H° = –2220 kJ/mol Calculate the ∆H° value for the reaction C3H4(g) + 2 H2(g) → C3H8(g) 22. Write the chemical equation of the reaction for which the standard enthalpy change is equal to the standard enthalpy of formation for caffeine, C8H10N4O2 .