Chapter 4 4 3 Types of Chemical Reactions

Chapter 4 (4. 3) Types of Chemical Reactions -Single Displacement

Single Displacement (SD) • one element in a compound is displaced by another element • In general: A + BC AC + B • A metal replaces another metal cation in a compound • Ex: Zn(s) + Fe(NO 3)2(aq) Zn(NO 3)2(aq) + Fe(s)

Single Displacement – Hydrogen • Ex: Mg(s) + 2 HCl(aq) Mg. Cl 2(aq) + H 2(g) • treat H as a metal • treat acids as ionic compounds • HCl(aq) H+(aq) Cl-(aq) • Ex: 2 Na(s) + 2 H 2 O(l) 2 Na. OH(aq) + H 2(g) • treat H as a metal • treat water as an ionic compound • H 2 O(l) H+(aq) OH-(aq)

Single Displacement – Try These • Ca(s) + H 2 O(l) • Al(s) + HCl(aq)

Activity Series • Through experimentation, chemists have ranked the relative reactivity of metals, including hydrogen (in acids and water). • A reactive metal will displace or replace any metal in a compound that is below it in the activity series. top most reactive bottom least reactive

Activity Series • See p. 130, Figure 4 • partial table: Metal Reactivity lithium Most reactive potassium hydrogen platinum gold Least reactive

Activity Series - Examples • Mg(s) + Zn. SO 4(aq) • Ag(s) + Ca. Cl 2(aq) • Au(s) + H 2 O(l)

Single Displacement – Type 2 • Non-metals, typically halogens, can also take part in single displacement reactions. • Ex: Cl 2(g) + 2 KBr(aq) 2 KCl(aq) + Br 2(l) • But, SD most occur as type 1

Activity Series • There is an activity series for the halogens • F > Cl > Br > I • Ex: I 2(s) + Ca. Br 2(aq) NR Halogen Reactivity F Most reactive Cl Br I Least reactive

Halogen Activity Series - Examples • Br 2(l) + Na. I(aq) • F 2(g) + Ca. Br 2(aq) • Cl 2(g) + KF(aq)