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ID: 1046256 • Letter: I

Question

iew Tell me what you want to do ce AaBbcl AaBbO Emphasis Heading 1 T Heading 2 1 Heading aStrong Subtitle Titile 1No Spac.. Subtle Em..Intes SubableTeNoSpa Subele E inte Styles Answer the following questions according to the data in the table above. TYPE your explanation(s) for full credit 1. Before a titration, your instructor let you to heat the solution to boiling point. What is the purpose of this operation? Why? 2. When the lab was over, you were told to rinse out glassware, especially the buret as early as possible. Why? Answer the following questions. Show details by hand 3. Balance the following chemical reaction in an acidic solution, and find both oxidizing agent and reducing agent Maox (a) + Fe(a)Mn()+ Fe (ag) 4. For the reaction below (1) Write the balanced equation below (2) If 1.75 g of Cu is produced, how much NHs in grams is consumed?

Explanation / Answer

3)

MnO4- + Fe+2 --------------- Mn+2 + Fe+3

+7            +2                          +2         +3

the oxidation state of Mn is decreases from +7 to +2 . so it undergoes Reduction. Hence MnO4- acts as Oxidising agent.

The oxidation state of Fe is increases from +2 to +3. so it undergoes oxidation. Hence Fe+2 acts as Reducing agent.

oxidation half reaction                  reduction half reaction

Fe+2 ---------- Fe+3            MnO4- ----------------- Mn+2     

Fe+2 --------- Fe+3 + e-                      MnO4- -------------------- Mn+2 + 4 H2O

                                                           MnO4- + 8H+ ------------- Mn+2 + 4 H2O

                                                            MnO4- + 8 H+ + 5e- ----------- Mn+2 + 4 H2O

     [ Fe+2 ------------- Fe+3 + e-]x5

    [ MnO4- + 8 H+ + 5e- ----------- Mn+2 + 4 H2O ]x1

5 Fe+2 ----------------- 5 Fe+3 + 5e-

MnO4- + 8 H+ + 5e- ----------- Mn+2 + 4 H2O

-------------------------------------------------------------------

MnO4- + 5 Fe+2 + 8 H+ ------------- Mn+2 + 5 Fe+3 + 4H2O

--------------------------------------------------------------------------------------

4)

NH3(g) + CuO(aq) ----------- N2(g) + Cu(s) + H2O(l)

2 NH3(g) + 3 CuO(aq) ------------ N2(g) + 3 Cu(s) + 3 H2O(l)

2 mole                                                        3 mole

molar mass of NH3= 17.0grams

molar mass of Cu= 63.5 grams/mole

according to equation

for the formation of 3 moles of Cu = 2 moles of NH3 is consumed

i.e 3x63.5 grams of Cu = 2x17.0grams of NH3

1.75 grams of Cu =?

                                  = 2x17x1.75/3x63.5=0.312 grams of NH3

mass of NH3 consumed= 0.312 grams.