SCH 3UI - Common Reactions That You Must Know

Activity Series
These elements are ranked most reactive to least reactive. A more reative element will often react to displace a less reactive element in a reaction.
K, Na, Ca, Mg, Al, Zn, Fe, Sn, Pb, H, Cu, Hg, Ag, Pt, Au
Common Reactions
1. A metal and oxygen gas will combine to make a metal oxide.
eg. 4 Fe + 3 O2 -----> 2 Fe2O3 eg. 4 Na + O2 -----> 2 Na2O
i) use the periodic table to predict the most likely valence of a transisiton metal.
ii) metals are always elemental , O2 is always diatomic.
2. A metal in acid will produce a metallic salt and hydrogen gas. A salt is a positive metal ion and a negative ion ending in "ide", "ate" or "ite".
eg. 2 Na + 2 HCl ----> 2 NaCl + H2(g)
Na displaces H from the moelcules because Na is more reactive.
eg. Pb + H2SO4 ------> PbSO4 + H2(g)
 - Copper and nitric acid do not perform this reaction.
Cu + HNO3 ---> Cu(NO3)2 + H2O + NO2(g)
3. Metals in water form metal hydroxides and hydrogen gas.
eg. 2 Na + 2 H2O -----> 2 NaOH + H2(g)
4. Metal oxides in water form metal hydroxides.
eg. K2O + H2O -----> 2 KOH
eg. Fe2O3 + H2O ------> 2 Fe(OH)3
5. Peroxides decompose to metallic oxides and oxygen gas
eg. 2 Na2O2 ------> 2 Na2O + O2
eg. 2 H2O2 ------> 2 H2O + O2
6. Non-metallic elements combine with oxygen to make non-metallic oxides.
eg. S + O2 ----> SO2
eg.C + O2 ------> CO2
7. Non-metallic oxides and water combine to form acids.
eg. SO2 + H2O -----> H2SO3
eg.NO2 + H2O -----> HNO3 + HNO
8. A metal and a compound may react in a single displacement reaction if the metal is more reactive than the metal in the compound. See the activity series above for more information.
eg. 2 Al(s) + 6 HCl ------> 2 AlCl3 + 3 H2(g)
eg. Cu(s) + 2 AgNO3 ----> 2 Ag(s) + Cu(NO3)2
eg. Ag(s) + Cu(NO3)2 -----> No reaction
9. An acid and a base will neutralize each other to create water and a salt.
eg. HCl + NaOH -----> H2O + NaCl
eg.2 H3PO4 + 3 Mg(OH)2 ------> 6 H2O + Mg3(PO4)2
10. Chlorates and perchlorates decompose on heating to give oxygen and a salt.
eg. 2 KClO3 ------heat------> 2 KCl + 3 O2
eg.KClO4 ------heat------> KCl + 2 O2

11. Some aqueous ions will react to form a gaseous product

eg.CO32- (aq) + acid -----> H2CO3(aq) -----> CO2(g) + HOH (CaCO3(aq) + 2HCl(aq) -----> CaCl2 + CO2(g) +HOH)

eg. SO32- (aq) + acid -----> H2SO3(aq) -----> SO2(g) + HOH (Na2SO3(aq) + 2HCl(aq) -----> 2NaCl + SO2(g) + HOH)

eg. NH4+1(aq) + base -----> NH4OH(aq) -----> NH3(g) + HOH (NH4Cl(aq) + KOH(aq) -----> KCl(aq) + NH3(g) + HOH)

eg.S2-(aq) + acid -----> H2S(g) (FeS(s) + 2HCl(aq) -----> FeCl2(aq) + H2S(g) )

eg.CN1-(aq) + acid -----> HCN(g) (KCN(aq) + HCl(aq) -----> KCl(aq) + HCN(g))