Predicting the Product in Single Replacement Reactions

Predicting the Product in Single Replacement Reactions • Using the Activity Series

Introduction • In a single replacement reaction, the metal ion in a salt solution is replaced by another metal. • AX(aq) + B(s) → BX(aq) + A(s) • For example: • Adding magnesium metal to a solution of silver chloride causes the magnesium to dissolve and the silver to precipitate out. • 2 AgNO3(aq) + Mg(s) → Mg(NO3)2(aq) + 2 Ag(s)

Introduction • In a single replacement reaction, the halide in a salt solution is replaced by another halide. • AX(aq) + Y2 → AY(aq) + X2 • For example: • Adding chlorine gas to a solution of sodium bromide causes the chlorine to dissolve and the bromine to come out as a liquid. • 2 NaBr(aq) + Cl2(g) → 2 NaCl(aq) + Br2(l)

Introduction • These kinds of reactions do not occur with all combinations of metals or halogens. • Some metals will replace some other metal ions in solution. • Some halogens will replace some other halogen ions in solution. • However, not every metal will replace every other metal ion in solution.

Metals • The metals that replace other metal ions are said to be “more active” than the metals they replace. • For example, in the reaction • 2 AgNO3(aq) + Mg(s) → Mg(NO3)2(aq) + 2 Ag(s) • Mg is more active than Ag. • By examining a series of reactions with solid metals and dissolved metal ions, we can build a list of metals based on activity. • We call this the “Activity Series.”

Metals • The most active metal is Li followed by Rb, K, Ba, Sr, Ca, and Na. • Each of these metals react with cold water and acids, replacing H. • Li(s) + H2O(l) → LiO(s) + H2(g) • 2 K(s) + HCl(aq) → 2 KCl(aq) + H2(g)

Metals • The most active metal is Li followed by Rb, K, Ba, Sr, Ca, and Na. • Each of these metals react with O2(g), forming oxides. • 2 Ba(s) + O2(g) → 2 BaO(s) • 2 Rb(s) + O2(g) → Rb2O(s)

Metals • The next most active set of metals is Mg followed by Al, Mn, Zn, Cr, Fe, and Cd. • Each of these metals react with H2O(g) and acids, replacing hydrogen. • Mg(s) + H2O(g) → MgO(s) + H2(g) • Zn(s) + 2 HNO3(aq) → Zn(NO3)2(aq) + H2(g)

Metals • The next most active set of metals is Mg followed by Al, Mn, Zn, Cr, Fe, and Cd. • Each of these metals react with O2(g), forming oxides. • 2 Zn(s) + O2(g) → 2 ZnO(s) • 4 Fe(s) + 3 O2(g) → 2 Fe2O3(s)

Metals • The next most active set of metals is Co followed by Ni, Sn, and Pb. • None of these metals react with H2O (hot or cold). • They do react with acids, replacing hydrogen. • Co(s) + 2 HNO3(aq) → Co(NO3)2(aq) + H2(g) • Pb(s) + H2SO4(aq) → PbSO4(aq) + H2(g)

Metals • The next most active set of metals is Co followed by Ni, Sn, and Pb. • Each of these metals react with O2(g), forming oxides. • 2 Ni(s) + O2(g) → 2 NiO(s) • 2 Sn(s) + O2(g) → 2 SnO(s)

Metals • The next most active set of metals is Sb followed by Bi, Cu, and Hg. • None of these metals react with water or acids. • Each of these metals react with O2(g), forming oxides. • 4 Sb(s) + 3 O2(g) → 2 Sb2O3(s) • 2 Cu(s) + O2(g) → 2 CuO(s)

Metals • The least active set of metals is Ag followed by Pt and Au. • Each of these metals are fairly unreactive. • None of these metals react with water or acids. • None of these metals react directly with O2(g) to form oxides. • They will form oxides, but only indirectly.

Metals • The Activity Series: most active increasing activity increasing activity increasing activity increasing activity increasing activity least active

Halogens • The most active halogen is F2 followed by Cl2, Br2, and I2. • Each of these halogens are reactive with a wide variety of elements and compounds. • The activity series just shows which is most reactive and least reactive.

Halogens most active • The Activity Series: • F2 • Cl2 • Br2 • I2 increasing activity least active

Using the Activity Series • The activity series is used to predict whether or not a single replacement reaction will occur. • First, we look at the ions in a solution. • Next, we look at the metal or halogen being added to the solution. • If the metal is higher up on the activity series list, then it goes into solution and the metal ion in solution precipitates out. • If the metal is lower down on the activity series list, then there is no reaction.

Using the Activity Series • The activity series is used to predict whether or not a single replacement reaction will occur. • First, we look at the ions in a solution. • Next, we look at the metal or halogen being added to the solution. • If the halogen is higher up on the activity series list, then it goes into solution and the halide ion in solution comes out as a solid, liquid, or gas. • If the halogen is lower down on the activity series list, then there is no reaction.

Using the Activity Series • For example: • We put zinc metal in a solution of copper(II) sulfate.

Using the Activity Series • For example: • We put zinc metal in a solution of copper(II) sulfate. Zn is more active than Cu.

Using the Activity Series • For example: • We put zinc metal in a solution of copper(II) sulfate. Zn is more active than Cu. Zn(s) will replace Cu2+(aq).

Using the Activity Series • For example: • We put zinc metal in a solution of copper(II) sulfate. • We predict that the solid zinc will dissolve in the solution (forming Zn2+ ions) and copper metal will precipitate out. • Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)

Using the Activity Series • For example: • We put magnesium metal in a solution of iron(III) chloride.

Using the Activity Series • For example: • We put magnesium metal in a solution of iron(III) chloride. Mg is more active than Fe.

Using the Activity Series • For example: • We put magnesium metal in a solution of iron(III) chloride. Mg is more active than Fe. Mg(s) will replace Fe3+(aq).

Using the Activity Series • For example: • We put magnesium metal in a solution of iron(III) chloride. • We predict that the solid magnesium will dissolve in the solution (forming Mg2+ ions) and iron metal will precipitate out. • 3 Mg(s) + 2 FeCl3(aq) → 3 MgCl2(aq) + 2 Fe(s)

Using the Activity Series • For example: • We put copper metal in a solution of iron(III) chloride.

Using the Activity Series • For example: • We put copper metal in a solution of iron(III) chloride. Fe is more active than Cu.

Using the Activity Series • For example: • We put copper metal in a solution of iron(III) chloride. Fe is more active than Cu. Cu(s) will not replace Fe3+(aq).

Using the Activity Series • For example: • We put copper metal in a solution of iron(III) chloride. • We predict that there will be no reaction. • Cu(s) + FeCl3(aq) → no reaction

Using the Activity Series • For example: • We add chlorine gas to a solution of iron(III) iodide.

Using the Activity Series • For example: • We add chlorine gas to a solution of iron(III) iodide. Cl2 is more active than I2.

Using the Activity Series • For example: • We add chlorine gas to a solution of iron(III) iodide. Cl2 is more active than I2. Cl2 will replace I−.

Using the Activity Series • For example: • We add chlorine gas to a solution of iron(III) iodide. • We predict that the chlorine gas will go into solution (forming a Cl− ion) and the iodine will come out as a solid. • 3 Cl2(g) + 2 FeI3(aq) → 2 FeCl3(aq) + 3 I2(s)

Using the Activity Series • For example: • We add chlorine gas to a solution of iron(III) fluoride.

Using the Activity Series • For example: • We add chlorine gas to a solution of iron(III) fluoride. F2 is more active than Cl2.

Using the Activity Series • For example: • We add chlorine gas to a solution of iron(III) fluoride. F2 is more active than Cl2. Cl2will not replace F−.

Using the Activity Series • For example: • We add chlorine gas to a solution of iron(III) fluoride. • We predict that there will be no reaction. • Cl2(g) + FeF3(aq) → no reaction

Summary • The activity series is used to predict whether or not a single replacement reaction will occur. • First, we look at the ions in a solution. • Next, we look at the metal or halogen being added to the solution. • If the metal is higher up on the activity series list, then it goes into solution and the metal ion in solution precipitates out. • If the metal is lower down on the activity series list, then there is no reaction.

Summary • The activity series is used to predict whether or not a single replacement reaction will occur. • First, we look at the ions in a solution. • Next, we look at the metal or halogen being added to the solution. • If the halogen is higher up on the activity series list, then it goes into solution and the halide ion in solution comes out as a solid, liquid, or gas. • If the halogen is lower down on the activity series list, then there is no reaction.

Predicting the Product in Single Replacement Reactions