# 7.4.5: Practice Classifying Reactions

#### Classify Reactions

Exercise $$\PageIndex{1}$$

Classify each reaction below as combination, decomposition, single displacement, double displacement, or combustion.

CaCO3 (s) $$\rightarrow$$ CO2 (g) + CaO (s)

decomposition

2 N2 (g) + 5 O2 (g) $$\rightarrow$$ 2 N2O5 (g)

combination

C5H10O (l) + 7 O2 (g) $$\rightarrow$$ 5 CO2 (g) + 5 H2O (g)

combustion

ZnCl2 (aq) + 2 AgNO3 (aq) $$\rightarrow$$ Zn(NO3)2 (aq) + 2 AgCl (s)

double displacement

Cl2 (g) + 2 KBr (aq) $$\rightarrow$$ Br2 (l) + 2 KCl (aq)

single displacement

2 H2 (g) + O2 (g) $$\rightarrow$$ 2 H2O (g)

combination

Mg (s) + HCl (aq) $$\rightarrow$$ MgCl2 (aq) + H2 (g)

single displacement

#### Total Ionic and Net Ionic Equations

Exercise $$\PageIndex{1}$$

Give the total ionic equation ("complete ionic equation") and the net ionic equation for each reaction below.

ZnCl2 (aq) + 2 AgNO3 (aq) $$\rightarrow$$ Zn(NO3)2 (aq) + 2 AgCl (s)

Total Ionic

Zn2+(aq) + 2 Cl1–(aq) + 2 Ag1+(aq) + 2 NO31–(aq) $$\rightarrow$$ Zn2+(aq) + 2 NO31–(aq) + 2 AgCl (s)

Net Ionic

2 Cl1–(aq) + 2 Ag1+(aq) $$\rightarrow$$ 2 AgCl (s)

H3PO4 (aq) + 3 NaOH (aq) $$\rightarrow$$ Na3PO4 (aq) + 3 H2(l)

Total Ionic

3 H1+(aq) + PO43– (aq) + 3 Na1+(aq) + 3 OH1–(aq) $$\rightarrow$$ 3 Na1+(aq) + PO43– (aq) + 3 H2(l)

Net Ionic

3 H1+(aq) + 3 OH1–(aq) $$\rightarrow$$ 3 H2(l)

#### Precipitation Reactions

Exercise $$\PageIndex{1}$$

Which of the following compounds would not be soluble in water (and would form a solid precipitate)?

LiCl    Pb(NO3)2    BaBr2    CaSO4    AgBr    Zn(C2H3O2)2    MgSO4    CaCl2    K2CO3    NiPO4

CaSO4    AgBr    NiPO4

For each of the reactions below, predict the products formed. Use the correct chemical formulas. Then balance the reaction and tell which product would be soluble ("aq" aqueous solution) and which would be insoluble ("s" solid precipitate).

CuCl2 (aq) + KOH (aq) $$\rightarrow$$

CuCl2 (aq) + 2 KOH (aq) $$\rightarrow$$ 2 KCl (aq) + Cu(OH)2 (s)

CaCl2 (aq) + Pb(NO3)2 (aq) $$\rightarrow$$

CaCl2 (aq) + Pb(NO3)2 (aq) $$\rightarrow$$ Ca(NO3)2 (aq) + PbCl2 (s)

Ba(ClO3)2 (aq) + Li2SO4 (aq) $$\rightarrow$$

Ba(ClO3)2 (aq) + Li2SO4 (aq) $$\rightarrow$$ 2 LiClO3 (aq) + BaSO4 (s)

#### Oxidation and Reduction

Exercise $$\PageIndex{1}$$

For each reaction below, tell which element is being oxidized and which is being reduced.

Mg (s) + HCl (aq) $$\rightarrow$$ MgCl2 (aq) + H2 (g)

Mg is being oxidized (0 to +2 charge),  Cl has no change (–1 to –1 charge), H is being reduced (+1 to 0 charge)

2 Al (s) + 3 Br2 (l) $$\rightarrow$$ 2 AlBr3 (s)

Cl2 (g) + 2 KBr (aq) $$\rightarrow$$ Br2 (l) + 2 KCl (aq)