Tuesday Homework Questions

Homework Questions 29-30 pg.113-114

By Kelly Moran

21.) a.) 

             i.) 68% (207.2/303.2= .68)

             ii.) 10% (5/10= 10) 

             iii.) 6.8 % (3.4/50) 

      

       b.) 

22.) While two thirds of the atoms are oxygen atoms the percent of oxygen by mass is not 67% because oxygen and carbon have different atomic masses. 

23.) Oxidation is when an ion or other reactant lose one more electrons. Reduction is the opposite and is when a reactant gains one or more electrons. 

24.) a.) (Au3+) + 3e- = Au 

       b.) V= (V4+) + 4e- 

       c.) Cu+= Cu - 1e 

25.) a.) Reduction

       b.) Oxidation

       c.) Reduction

26.) a.) Zinc was oxidized because it became 2 positive in its sum. 

       b.) Nickel gained 2 electrons because it went from positive 2 to nothing.

       c.)  The reducing agent is zinc in this reaction.

27.) a.) 2 K has been oxidized because it changes into 2 K plus therefore it lost 2 electrons 

       b.) Hg 2 plus has been reduced because it changes in Hg meaning it gained 2 electrons.

       c.) Hg is the oxidizing agent because it gained two electrons. 

28.) a.) Al + Cr3= Al3 + Cr

       b.) (Mn2+) +  Mg= Mn + Mg2 

29.) a.) Electrometallurgy is a process using electric currents to supply electrons to metal ions thus reducing them.

       b.) Pyrometallurgy involves treating metals with thermal energy (heat) and adding carbon to add electrons. 

       c.) Hydrometallurgy is a process that involves treating ores and other metal-containing materials with reactants in water solution and thus gets the metal out of the ore. 

30.) a.) Hydrometallurgy 

       b.) Hydrometallurgy