7.c Solubility key - Homework PDF

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Solubility and Precipitation Reactions Activity The extent to which a substance may be dissolved in water, or any solvent, is quantitatively expressed as its solubility, defined as the maximum concentration of a substance that can be achieved under specified conditions. Substances with relatively large solubilities are said to be soluble. Substances with relatively low solubilities are said to be insoluble, and these are the substances that readily precipitate from solution. A precipitation reaction occurs when two solutions are mixed and a solid precipitates (or forms). The Solubility Rules Soluble Ionic Compounds contain these ions NH4+ group I cations: Li+, Na+, K+, Rb+, Cs+ C2H3O2NO3ClO3ClBrIF-

Exceptions none

compounds with Ag+, Hg22+, and Pb2+

compounds with group 2 metal cations, Pb2+, Fe3+, and Ag+ compounds with Ag+, Ba2+, Ca2+, Hg22+, Pb2+ and Sr2+

SO42Insoluble Ionic Compounds contain these ions CO32PO43S2OH-

Exceptions compounds with group 1 cations and NH4+ compounds with group 1 cations and Ba2+

Example 1: Determine if K2CO3 is soluble in water. Solubility Rule: Carbonate compounds are insoluble except when with group 1 cations or NH4+. K2CO3 is a carbonate, but K+ is a group 1 cation so the compound is soluble. Determine if FeCl2 is soluble in water. Solubility rule. Chlorides are soluble except when with Ag+, Hg22+, and Pb2+. Therefore, FeCl2 is soluble.

1. Determine if the following species are soluble in water or if they are insoluble. a. (NH4)2CO3

soluble (all ammoniums are soluble)

b. Pb(NO3)2

soluble (all nitrates are soluble)

c. Zn(C2H3O2)2 d. KBr

soluble (all acetates are soluble) soluble (all group 1 cation compounds are soluble)

e. CoCO3

insoluble (carbonates are generally insoluble)

f. BaSO4

insoluble (sulfates are generally soluble, but Ba2+ is an exception)

g. PbCl2

insoluble (chlorides are generally soluble, but Pb2+ is an exception)

h. Na2CO3

soluble (all group 1 cation compounds are soluble)

2. Add the chemical states to each species and balance the chemical reactions below. _1__ Na2SO4 (_aq_) + __1_ CaCl2 (_aq_) → _1__ CaSO4 (_s_) + _2__ NaCl (_aq_)

_1__ Ba(OH)2 (_aq_) + _1_ K2CO3 (_aq_) → _1_ BaCO3 (_s_) + _2_ KOH (_aq_)

_1_ Fe(NO3)3 (_aq_) + _3_ NH4OH (_aq_) → _1_ Fe(OH)3 (_s_) + _3_ NH4NO3 (_aq_)

Example 2: A solution of sodium chloride is mixed with a solution of silver nitrate. Predict the products and decide if a precipitation reaction has occurred. Molecular equation: write out the formula of every compound with state and balance the equation NaCl (aq) + AgNO3 (aq) → NaNO3 (aq) + AgCl (s) Yes, a precipitation reaction occurs. Example 3: A solution of potassium chloride is mixed with a solution of ammonium nitrate. Predict the products and decide if a precipitation reaction has occurred. Molecular equation: write out the formula of every compound with state and balance the equation KCl (aq) + NH4NO3 (aq) → KNO3 (aq) + NH4Cl (aq) No reaction has occurred, all the ions are just dissolved in solution.

3. Determine the products for each of the following reactions and decide if a precipitation reaction has occurred. Then, balance the chemical equation. a. _1__K2CO3 (aq) + _1_ SnCl2 (aq) → 1 SnCO3 (s) + 2 KCl (aq)

b. _1__Na2S (aq) + _1_ Pb(C2H3O2)2 (aq) → 2 NaC2H3O2 (aq) + PbS (s)

c. _1__Na2CO3(aq) + _1__Fe(NO3)2 (aq) → 2 NaNO3 (aq) + FeCO3(aq)

d. __1__CaCl2 (aq) + _1__Na2SO4 (aq) → CaSO4 (s) + 2 NaCl (aq)

e. _1__Na3PO4 (aq) + _1__Fe(NO3)3 (aq) → 3 NaNO3 (aq) + FePO4 (s)

f. _1__ZnCl2 (aq) + __1_ Cu(NO3)2(aq) → No reaction. (all species are aqueous) Zn(NO3)2 (aq) + CuCl2 (aq)...