Week 6 (Selective Precipitation)

Question 1

Selective Precipitation

Answer 1

strategic use of solubility rules (applying order of operations to ion exchange reactions) to separate ions in aqueous solutions by using a reagent that precipitates one ion while leaving other ions in solution

Question 2

Limiting Reactant

Answer 2

the reactant that is completely consumed when the chemical reaction is completed (unless you put in perfect amounts, something in the reaction will limit the amount of product you get)

Question 2

Applications of selective precipitation

Answer 2

-water treatment/purification of municipal water systems
-separation of particularly toxic chemicals for specialty disposal

Question 3

Limiting Reactant Smore’s Example

Answer 3

-2 graham crackers + 1 chocolate + 1 marshmallow -> 1 s’more
-If you have 18 graham crackers, 10 chocolate pieces, and 7 marshmallows, you could make 7 s’mores (marshmallow is limiting reactant)

Question 4

If we combine 400g SO2, 175g O2, and 125g H2O, what is limiting reactant?
2SO2 + O2 + 2H2O -> 2H2SO4

Answer 4

-convert g to mols for each compound
-(400/64.07g SO2)(2/2 mol H2SO4:SO2)= 6.24 mol H2SO4
-(175/31.99g O2)(2/1 mol H2SO4:O2)= 10.94 mol H2SO4
-(125/18.02g H2O)(2/2 mol H2SO4/H2O)= 6.94 mol H2SO4
-SO2 is limiting reactant
-mass of H2SO4= (6.24 x 98.08g H2SO4)= 612g H2SO4

Question 5

Theoretical Yield

Answer 5

the amount of product obtained in a chemical reaction (based on calculations, not actual amount)

Question 6

Actual Yield

Answer 6

the quantity physically obtained from a chemical reaction conducted in lab

Question 7

Percent Yield

Answer 7

how much we actually obtained vs. how much we expected to get (actual/theoretical x 100)