 is an equilibrium expression for a chemical equation that represents the dissolving of an ionic compound  K sp = The product of the concentration of a salt’s ions in a saturated solution, each raised to the appropriate power.  A large K sp means that the compound is very soluble (forward reaction is favored)  A small K sp means the compound is not very soluble (reverse reaction is favored)

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 Ksp is a measure of solubility; it is not actual solubility (as in grams per liter). We can compute the how much will dissolve from the K sp value.  Steps to determine how much will dissolve Write the equation for the reaction Write the K sp expression Get K sp from the table Take the appropriate root Convert to grams/liter

  Take the appropriate root 2.5x10 -5 = [Mg 2+ ] [CO 3 2- ] [Mg 2+ ] = [CO 3 2- ] = 5.0x10 -3 M  Convert to grams/liter ( 5.0x10 -3 mol/L)(84.32 g/mol) =  0.42 g/L How many grams of MgCO 3 can be dissolved in 1.00 L of water if at 50°C, the K sp = 2.5x10 -5 ?

 Take the appropriate root 3.7x = [Fe 3+ ] [S 2- ] [Fe 3+ ] = [S 2- ] = 6.1x M  Convert to grams/liter (6.1 x mol/L)(87.92 g/mol) =  5.4x10 -8 g/L How many grams of FeS will dissolve per liter if at 44°, the K sp = 3.7x ?

 How many grams of AgBr can be dissolved in 2.00 L of water if at 20°C, the K sp = 4.8x ?  How many grams of Ca(OH) 2 will dissolve in one liter of water if at 15°C, the K sp = 1.3x10 -6 ?