FUNDAMENTALS I - Precipitation Reactions

solubility

Soluble substances are those that dissolve to a significant extent in a specific solvent

electrolytes

a substance that is present as ions in solution

strong electrolytes

•  present entirely as ions in solution (ex. Soluble ionic compounds, strong acids, strong bases)

weak electrolytes

incomplete ionization, mostly present as a pair (ex. CaCO₃)

insoluble substance

one that does not dissolve significantly in a specific solvent

nonelectrolyte

does not form ions in solution, does not conduct electricity

solubility table

some ion pairs are soluble in water, some are not. (given on formula sheet)

dissolution

Dissolving of ionic species into a solvent

precipitation

formation of a solid when insoluble ion species are combined in a solvent. The sold formed is called a “precipitate”

• Solutions are clear

• Suspensions are cloudy, turbid

• Precipitates separates out

complete ionic reactions

show all the species as they actually exist in solution - dissolved ionic compounds exist as separate aqueous ions, so the ions are shown separately.

• When two aqueous species are combined and if a solid, liquid, or gas, do not form, no reaction occurs.

• Don’t separate ions of insoluble species

spectator ions

ions that play no direct role in the reaction and appear as both reactants and products.

Can be canceled to give the net ionic equation, the chemical equation that displays only the net change that took place after the reaction.

precipitation reaction

the formation of an insoluble substance when two electrolyte solutions are mixed

writing a net ionic equation

1) balance the equation

2) seperate all ions

3) cancel spectator ions

4) final net reaction!

predicting outcome of precipitation reaction

use solubility table to determine what can be dissolved

When two aqueous species are combined and if a solid, liquid, or gas, do not form,

no reaction occurs

dont separate which ions

ions of insoluble species