Classifying Chemical Reactions

Single Displacement Reactions

When an element takes the place of another element that is in a compound.Could be a metal replacing a metal or an non-metal replacing a non-metal.General formula: – A + BC AC + B (A is a metal)– A + BC BA + C (A is a non-metal)– + +

Examples…

Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + Ag(s)

This reaction does not go in reverse! Why can’t Ag replace Cu? It is because of the reactivity of the metals.We have an activity series to help us predict what will react with what.The Activity Series is a list of elements that is organized according to their chemical reactivity.

Activity Series for Metals (pg. 192, fig. 5.13)

LithiumPotassiumCalciumSodiumMagnesiumAluminumZincIronNickelTinHydrogenCopper SilverPlatinumGold

Most reactive

Least reactive

Hydrogen???

Notice that hydrogen is on the activity series and it is not a metal! Because hydrogen is positively charged as an ion, it can take the place of metals in compounds.The metals above hydrogen in the series can replace hydrogen, but the metals below hydrogen cannot.

Example 1 (Metals)

Use the activity series to predict if the following single displacement reaction occurs.

Al(s) + NiBr3(aq) __________Step 1: Check Activity Series chart.

Step 2: Form new compound. Cross over the ionic charges.

Step 3: What does the other element look like on its own?

Example 1 (Metals)

Use the activity series to predict if the following single displacement reaction occurs.

Al(s) + NiBr3(aq) __________

Step 4: Write the equation and balance.

Example 2: Non-metals

The ion of a non-metal is negatively charged, so it can be replaced with only another non-metal.

F2(g) + 2NaI(s) I2 (s) + 2NaF (s)

There is a separate activity series for non-metals

Activity Series for Non-metals

FluorineChlorineBromineIodine

Most reactive

Least reactive

Double Displacement

a chemical reaction in which the positive ions of 2 compounds change places and form 2 new compounds.

General chemical equation:

– AB + CD AD + CB

- + +

Example

Complete and balance the following double displacement reaction. You do not need to predict the states of the products.

NaCl (aq) +AgNO3 (aq) Step 1: This is a double displacement reaction. Therefore, the two cations in the reacting compounds switch places.

Step 2: Form new compounds. Cross over the ionic charges.

Example

Complete and balance the following double displacement reaction. You do not need to predict the states of the products.

NaCl (aq) +AgNO3 (aq)

Step 3: Write the chemical equation and balance.

You Try It!!

p. 193 # 1, 2

p. 195 # 2, 4

p. 196 # 1, 2