1. 7.8 Single- Replacement Reactions By: Olivia Stone, Anna Mecca, and Michael Lazarow

2. Single-Replacement Reactions:  In a single-replacement reaction, also known as a single displacement reaction, atoms of an element replace the atoms of a another element in a compound.  In a Single Replacement Reaction, a metal replaces a metal, or a nonmetal replaces a nonmetal.

3. Example of Single Replacement Reactions: CB

4. Activity Series of Metals Table: The activity series of metals is a list of metals in order of decreasing reactivity. You should use this table when solving single replacement problems. Example: 3Ca (s) + 2AlPO 4(aq) Ca 3 (PO 4 ) 2(aq) + 2Al (s) Al (s) + Ca 3 (PO 4 ) 2(aq) No Reaction

5. Additional Facts:  If a nonmetal replaces a nonmetal it is usually limited to the halogens (a group in the periodic table consisting of five chemically related elements which are F, Cl, Br, I, and At.  The activity of the halogens decreases as you go down Group 7a or Column 17 of the periodic table. (Just like the activity series of metals but this time, nonmetals).

6. Li (s) + NaOH (aq) Is this reaction possible? First you want to find the metal that is doing the replacing and the metal that is being replaced. Those would be lithium and sodium. Next, you want to see if the metal replacing, (lithium) is above the metal being replaced, (sodium) on the activity series. It is, so this reaction is possible. Then, don’t forgot to balance the equation if needed. Li (s) + NaOH (aq) LiOH(aq) + Na(s )

7. Al (s) + Mg 3 (PO 3 ) 2(aq) Is this reaction possible? Find the metal replacing and the metal being replaced. Aluminum is replacing. Magnesium is being replaced. Now find them on the activity series. Is aluminum above magnesium on the activity series? No, therefore this reaction is impossible. Aluminum cannot replace magnesium. Al (s) + Mg 3 (PO 3 ) 2(aq) No Reaction

8. Diagram of Single Replacement:

9. Single Replacement Facts:  A single replacement reaction will only take place if a more reactive element is replacing a less reactive one.  With single replacement reactions, elements that form cations can only replace cations and elements that form anions can only replace anions.  A metal displaces a cation from a compound and a nonmetal displaces an anion.

10. Complete the equation for this single replacement reaction that takes place in a water solution. Balance each equation. If a reaction does not occur, write “no reaction”. Zn (s) + AgCN (aq) → ?

11. The End… Have questions? Don’t be afraid to ask