Question

Experiment 8 Double Replacement Reactions Background: Some reactions have the net effect of causing the cation of each reactant to trade places, forming a compound with the other anion. These reactions are known as double replacement reactions. In the example below (unbalanced equation), the barium and sodium cations switch places so that barium forms a product with sulfate while sodium forms a product with chloride. Note that the formula of each product is determined by the charges of the ions, NOT by the subscripts in the reactants. BaCl(aq) +NaSO4(ag) - Na Cl + BaSO? formula of products - NaClaq) + BaSO4(s) An equation using the double replacement strategy can be written out to predict if a reaction (a chemical change) will occur. A reaction is predicted to occur if at least one of the potential products is either an insoluble solid (a precipitate), a gas, or a weak or nonelectrolyte. A weak electrolyte is a compound that only partially dissociates into ions (remaining mostly as undissociated molecules) when dissolved while a nonelectrolyte does not dissociate at all, remaining entirely as undissociated molecules when dissolved. The table on page X shows the behavior of many combinations of cations and anions in forming potential double replacement products. Example 1: The reactants shown below are predicted to react because one of the products formed is an insoluble solid. Notice that the table lists p (precipitate) for barium sulfate double replacement BaCl(aq) + Na, SO4(aq) 2 NaCl(aq) + BaSO4(s) Example 2: The reactants shown below are predicted to react because liquid water, a nonelectrolyte, is a product. It should be noted that the reaction of any acid (a source of H' cations) with a compound that contains the hydroxide anion will give a similar double replacement reaction. HBr(aq) + KOH(aq) double replacement HOH = H2O(0) + KBr(aq) Example 3: The reactants shown below are predicted to react because one of the products formed is a weak electrolyte. Notice the table lists w (weak electrolyte for acetic acid). double replacement HCl(aq) + NaC2H,O,(aq) -NaCl(aq) + HCH.Oxaq) Example 4: The reactants shown below are predicted to react because one of the products formed is a gas. The formation of a gas is an observation of a decomposition reaction. Notice the table lists d (decomposition) for carbonic acid double replacement 2 Hl(aq) + K,CO, (aq) - 2 Kl(aq) + H2CO3(aq) decomposition H.CO:(aq) - CO2(g) + H2O(1) 2 Hl(aq) + K:CO, (ag) 2 Kl(aq) + CO2(g) + H2O(l) Overall:

Answer 1

1. K2SO₂ (aq) + 2 HBrlag) 2 KBr (GE) + H20ll) + SO2(g) 2 a) Zn Br2 + Mg (C43 (OD) (99) (99) Mg Br 2 (98) & ZU(CH3Cord), (aq) 6) HNO3(aq) + NH4 OH (99)- NHU NO3 + H20le) (ar) Na 2503 +2KOH (29) ag ) 2 NaOH at K2503 @g) læg) d) (NH4) coz + 2HC -) 2N Hull + CO2 + H2O (ar) aq) (a) () (l) C) 2K3 P04 + 3 Ca Iz - Casoy) +6KI a) az) (P) (aq) & ) Pb(NO3 + H2504 pb soy + 2 HNO3 (49) (aq) o - (aq) g) AgNO3 + Lidl - Agel & LINO an) cag) ( P ag)