Single Replacement & Double Replacement Unit 6 – Lesson 3 Single Replacement & Double Replacement

A + BC  AC + B 4. Single Replacement (SR) A single element and a compound become a different element and a different compound. A + BC  AC + B

In this class, the most common SR will be a metal-metal replacement Most reactive Least reactive In this class, the most common SR will be a metal-metal replacement If the metal that is single is more reactive than the one in the compound, the metals will switch places Use the activity series to determine reactivity of the metals Fe(s) + CuSO4 (aq) Cu(s) + FeSO4(aq) video

2 AgNO3(aq) + Cu(s)  2 Ag(s) + Cu(NO3)2(aq) Most reactive Least reactive Cu(s) + AgNO3(aq)  Ag(s) + Cu(NO3)2(aq) 2 AgNO3(aq) + Cu(s)  2 Ag(s) + Cu(NO3)2(aq)

Complete & Balance Mg (s) + NaBr(aq)  no rxn (reaction) AgNO3(aq) + Mg(s)  Ag(s) + Mg(NO3)2(aq) 2 AgNO3(aq) + Mg(s)  2 Ag(s) + Mg(NO3)2(aq) FeI3(aq) + K(s)  KI(aq) + Fe(s) FeI3(aq) + 3 K(s)  3 KI(aq) + Fe(s)

* Notice it matches the positions from the periodic table! Another example of SR would be a halide-halide replacement Halide = Halogen If the halogen that is single is more reactive than the one in the compound, the halogens will switch places Most reactive Least reactive Use the activity series to determine reactivity of the halides * Notice it matches the positions from the periodic table! F2 + CaCl2  Cl2 + CaF2 Br2 + MgCl2  no rxn (reaction) Cl2 + CaI2  I2 + CaCl2

AB + CD  AD + CB 5. Double Replacement (DR) When the cations in two compounds switch places/partners. AB + CD  AD + CB

In aqueous solutions, the dissolved compound is broken into ions Typically occurs between two ionic compounds in aqueous solutions. In aqueous solutions, the dissolved compound is broken into ions

**If both products are aqueous the reaction will NOT occur** A reaction will ONLY occur if one of the possible products is either a… a. precipitate (solid) AgNO3(aq) + NaCl(aq)  AgCl(s) + NaNO3(aq) A precipitate forms when one of the products is insoluble (does not dissolve) in water. Use the solubility rules in the reference packet to determine if either product is insoluble. **If both products are aqueous the reaction will NOT occur**

How to READ the Solubility Rules Look up the anion (second part) of the compound AgNO3 Ba(OH)2 MgCO3 MgF2 If the anion is on the soluble side it will be aqueous UNLESS it is an exception If the anion is on the insoluble side it will be solid UNLESS it is an exception AgNO3 - aqueous MgCO3 - solid Ba(OH)2 - aqueous MgF2 - solid

Predict the possible products to determine if the reaction will occur. **If both products are aqueous the reaction will NOT occur** BaCl2(aq) + KNO3(aq)  Ba(NO3)2 (aq) + KCl (aq) NO RXN YES! FeCl3 (aq) + Na3PO4 (aq)  NaCl (aq) + FePO4 (s) FeCl3 (aq) + Na3PO4 (aq)  3 NaCl (aq) + FePO4 (s) NO RXN AgF (aq) + KNO3 (aq)  AgNO3 (aq) + KF (aq) AgNO3 (aq) + NaCl (aq)  NaNO3 (aq) + AgCl (s) YES! AgNO3 (aq) + NaCl (aq)  NaNO3 (aq) + AgCl (s)

b. water Ex. Acid-base neutralization HCl (aq) + NaOH (aq)  NaCl (aq) + H2O (l) HNO3(aq) + NaOH(aq)  NaNO3(aq) + H2O (l) c. gas HCl (aq) + NaHCO3 (aq)  NaCl (aq) + CO2 (g) + H2O (l) For a double replacement reaction to occur one product has to be a solid, gas or H2O.

Testing for Common Products Oxygen: A glowing splint will burst into flame in pure oxygen. Hydrogen: A lighted splint inserted into an inverted test tube full of Hydrogen (H2 is lighter than air hence the inverted tube), will produce a 'squeaky' 'POP'! as it ignites. CO2: CO2 will turn lime water cloudy. Also, a test tube full of CO2 (not inverted as it's heavier than air) will extinguish a burning splint inserted into it. The standard test for water is to use cobalt (II) chloride paper. This is paper soaked in cobalt(II) chloride (CoCl2) solution. It turns from blue to pink upon exposure to water.