ChemLab #17 is stoichiometry − a mass-mass question!

1. When silver nitrate is dissolved in water, Ag⁺_(aq) and NO₃⁻_(aq) are produced.
    
2. The mole ratio in your sample of AgNO₃ is 1 mole of silver to 1 mole of silver nitrate. Do the dimensional analysis calculation on your lab report guide (step #2). This will be the theoretical number of grams of silver you should be able to recover from solution.
    
3. To recover silver metal, Ag_(s), an electron must be added to each Ag⁺ in solution.
    
   • The nitrate ion, NO₃⁻, will not take part in the reaction and can be ignored.
    
4. You must find a reactant that will provide electrons to the silver ions.

   Here's an example of how to do it:

    
   • Take this reaction:   Mg_(s) + Co⁺²_(aq) → Mg⁺²_(aq) + Co_(s)
      
   • Magnesium metal provides electrons for cobalt ions to become cobalt atoms.
      
   • Here's the reaction as a diagram:

     

   • The chemical reaction is cobalt ions taking electrons away from magnesium metal.
      
   • When cations (positive ions) take electrons away from a metal, it is called oxidation.

     

   • Different metals vary in the ease with which they are oxidized. A list of metals arranged in order of increasing ease of oxidation is called an activity series - click on the table icon to see an activity series.
      
     • Metals at the top are active metals, easily oxidized, and readily form compounds.
        
     • Metals at the bottom are noble metals, not easily oxidized, and have low reactivity.
        
     • Any metal on the list can be oxidized by the ions of metals below it.
      
   • Notice that cobalt is below magnesium on the activity series, so cobalt ions will take electrons away from (oxidize) magnesium metal.

    
5. Now back to your reaction.
    
   • You need to find a metal that will do this:

     

   • Use the activity series to do that.
      
   • Write the single displacement reaction on your lab report guide (step #3), and you are ready to plan the lab ( step #4).