Precipitation Reaction

Precipitation Reactions §

Precipitate - insoluble solid that separates from solid Refer to Solubility Rules for these types of reactions

ppt = precipitation rxn = reaction

This is similar to double displacement reactions

Reactions that will create precipitate (when a solid forms)

When 2 aqueous solutions of iconic compounds are mixed, an insoluble substance forms

Pb(NO) (aq) + 2 NaI (aq) -> PbI (s) + 2NaNO (aq) Molecular Formula

Pb + 2NO + 2 Na + 2I -> PbI (s) + 2Na + 2NO Complete ionic equations (dissect every compound except the precipitate so everything that’s aqueous)

Pb + 2I -> PbI (s) Net ionic equation

Na and NO are spectator ions

Stoichiometry of ppt reactions §

100.0 mL of 0.100 M solution of barium chloride is mixed with 100.0 mL of 0.100 M solution of iron (III) sulfate

Step 1: what species are present?

Ba Cl Fe SO

Step 2: write the balanced net ionic equation

Ba + SO -> BaSO (s)

Step 3: Calculate the # of moles of each reactant

0.1000 L * 0.100 BaCl = 0.0100 mol BaCl (rounded using Significant Digits)

0.100 mol BaCl * = 0.0100 mol Ba

for every BaCl there’s 1 Ba ion hence the 1:1 mole ratio

0.1000 L * 0.100 M Fe(SO) = 0.0100 mol Fe(SO)

0.0100 mol Fe(SO) * = 0.0300 mol SO

Step 4: Determining the limiting reactant

0.0100 mol Ba * = 0.0100 mol SO

0.0300 mol of SO available and need only 0.100 mol so Ba is the L.R

Step 5: Calculate the # of moles of product

0.0100 mol of Ba * = 0.0100 mol of BaSO

Step 6: convert from moles to grams

0.0100 mol of BaSO * = 2.33 grams of BaSO