Spring 2019 CSUSM CHEM 175 8. Which statements are true? Select ALL. that apply. a) Dissolution of ammonium nitrate is an endothermic reactio b) Hydrogen gas evolves when calcium carbonate reacts...
Spring 2019 CSUSM CHEM 175 8. Which statements are true? Select ALL. that apply. a) Dissolution of ammonium nitrate is an endothermic reactio b) Hydrogen gas evolves when calcium carbonate reacts with hydrochloric acid. c) The acid-base neutralization reaction is exothermic. ) The value of enthalpy change, AH, of calcium chloride dissolution is positive. sample contains an unknown amount of Fe?'which is titrated with a KMnO, solution in acidie tions to determine the iron composition by mass. A standardized KMnOs solution is needed for of this sample. The primary standard selected is ferrous ammonium sulfate hexahydrate (FAS), Fe(NH)(SO4) 6H20 (Mw- 392.21 g/mol) to find the exact molarity of the KMn04 solution. esi The balanced net ionic equation for this redox reaction is as follows: 5Fe2+ + MnO' + 8H' → 5Fe3+ + Mn2+ + 41120 A. The student weighs 0.2094 grams of FAS and finds that 12.34 mL. of KMnO4 solution is needed to titrate the FAS sample, what is the molarity of this KMn04 solution? KMnO4]- B. The student then weighs 0.1211 grams of the unknown solid and finds it requires 13.45 mL of the standardized KMnO4 solution (from part A) to titrate. What is the mass of iron (Fe, MW 55.85 g/mol) in this sample? Mass of Fe2+ in unknown sample C. What is the % iron by mass in the unknown sample for Part B? % mass of Fe2+ in unknown samples D. Suppose a student spilled some FAS after weighing it but before performing the titration to standardize the KMn04 solution. What effect, if any, would this have on the standard molarity of the KMnOs solution? Explain your answer clearly following the steps in the calculation. 61Page
Spring 2019 CSUSM CHEM 175 8. Which statements are true? Select ALL. that apply. a) Dissolution of ammonium nitrate is an endothermic reactio b) Hydrogen gas evolves when calcium carbonate reacts with hydrochloric acid. c) The acid-base neutralization reaction is exothermic. ) The value of enthalpy change, AH, of calcium chloride dissolution is positive. sample contains an unknown amount of Fe?'which is titrated with a KMnO, solution in acidie tions to determine the iron composition by mass. A standardized KMnOs solution is needed for of this sample. The primary standard selected is ferrous ammonium sulfate hexahydrate (FAS), Fe(NH)(SO4) 6H20 (Mw- 392.21 g/mol) to find the exact molarity of the KMn04 solution. esi The balanced net ionic equation for this redox reaction is as follows: 5Fe2+ + MnO' + 8H' → 5Fe3+ + Mn2+ + 41120 A. The student weighs 0.2094 grams of FAS and finds that 12.34 mL. of KMnO4 solution is needed to titrate the FAS sample, what is the molarity of this KMn04 solution? KMnO4]- B. The student then weighs 0.1211 grams of the unknown solid and finds it requires 13.45 mL of the standardized KMnO4 solution (from part A) to titrate. What is the mass of iron (Fe, MW 55.85 g/mol) in this sample? Mass of Fe2+ in unknown sample C. What is the % iron by mass in the unknown sample for Part B? % mass of Fe2+ in unknown samples D. Suppose a student spilled some FAS after weighing it but before performing the titration to standardize the KMn04 solution. What effect, if any, would this have on the standard molarity of the KMnOs solution? Explain your answer clearly following the steps in the calculation. 61Page