Equation Types Balancing Equations

Points of Interest: Know diatomics: H 2, N 2, O 2, F 2, Cl 2, Br 2, I 2  means “yields” and shows direction of action (g) = gas, (s) = solid, (l) = liquid, (c) = crystalline solid, (aq) = aqueous solution – dissolved in water ∆ above arrow shows heat has been added  shows reaction is reversible

Single Displacement Reactions A more reactive metal displaces a less reactive metal (in a compound) or a more reactive nonmetal displaces a less reactive nonmetal (in a compound) General form: Element + compound  element + compound Check Activity Series Chart to determine if reaction took place [page 217]

Single Displacement Examples: Zn (s) + Cu(NO 3 ) 2 (aq)  Cu (s) + Zn(NO 3 ) 2 (aq) Cu (s)+ 2 AgNO 3 (aq)  2 Ag (s) + Cu(NO 3 ) 2 (aq) Mg (s) + 2HCl (aq)  _____ (g) + _____ (aq)

Double Displacement Reactions The metals present in two compounds (in water solution) change places to form two new compounds. A double displacement reaction occurs only if a solid precipitate forms (check solubility chart), or gas or water are created as products. Examples are precipitation reaction and acid-base neutralization reactions.

Double Displacement Examples AgNO 3 (aq) + NaCl (aq)  AgCl (s) + NaNO 3 (aq) NaOH (aq) + HCl (aq)  NaCl (s) + H 2 O (l) Ba(NO 3 ) 2 (aq) + Na 2 SO 4 (aq)  __ (s) + __ (aq)

Synthesis Reactions 2 or more substances combine to form one new substance 2H 2 (g) + O 2 (g) + heat  2 H 2 O (l) CaO (s) + H 2 O (l)  Ca(OH) 2 (aq) Ca (s) + Cl 2 (g)  CaCl 2 (s)

Synthesis Reactions cont. SO 2 (g) + H 2 O (l)  _________ (aq) Al (s) + O 2 (g)  ________ (s) balance

Decomposition Reactions A compound is broken down into components. Energy must be supplied to break down the complex compound into simpler substances. ∆ 2 HgO (s)  2 Hg (l) + O 2 (g)

Decomposition Examples 2 H 2 O (l)  2 H 2 (g) + O 2 (g) H 2 O 2 (l)  H 2 (g) + O 2 (g) KClO 3 (s)  _______ (s) + ________ (g) balance also

Decomposition Problems: Some products are unstable and break down (decompose) as they are produced during the reaction: H 2 CO 3 (aq)  H 2 O (l) + CO 2 (g) H 2 SO 3 (aq)  H 2 O (l) + SO 2 (g) NH 4 OH (aq)  NH 3 (g) + H 2 O (l)

Other reaction types: Dehydration – removal of water CuSO 4 · 5H 2 O (s)  CuSO 4 (s) + H 2 O (l) Polymerization – using a subunit molecule (called a monomer) as a building block of a many unit chain or structure examples: DNA, proteins, carbohydrates

Other Reaction Types Hydrogenation – adding hydrogen (in place of double/triple bonds) Combustion – substance combines with oxygen to produce CO 2 and H 2 O (if combustion is incomplete or not hot enough some CO may be formed as well)

Reaction Types Neutralization – when an acid and base combine to form water and salt NaOH (aq) + HCl (aq)  NaCl (s) + H 2 O (l) H 3 PO 4 (aq) + 3NaOH (aq)  3H 2 O (l) + Na 3 PO 4 (aq)