Reaction Types

How do we know what will be produced in a chemical reaction? Recognizing a pattern of reactivity gives a broader understanding than memorizing a large number of reactions Would expect elements of the same family to behave similar 2K + 2H 2 O → 2KOH + H 2 What will happen if Na combines with water?

Five Types of Reactions Combustion – rapid reaction that produces flame Occurs in hydrocarbons (compounds of C, H, and sometimes O) Reaction of hydrocarbon with oxygen to produce carbon dioxide and water C 3 H 8 + 5O 2 → 3CO 2 + 4H 2 O 2CH 3 OH + 3O 2 → 2CO 2 + 4H 2 O

Combination or Synthesis Two reactants combine to form a single product A + B → AB Examples C + O 2 → CO 2 N 2 + 3H 2 → 2NH 3 CaO + H 2 O → Ca(OH) 2

Decomposition Single reactant breaks apart to form two or more substances AB → A + B Examples 2KClO 3 → 2KCl + 3O 2 CaCO 3 → CaO + CO 2

Single Replacement One element replaces another similar element in a compound A + BX → AX + B Examples Fe + 2HCl → FeCl 2 + H 2 Zn + CuSO 4 → ZnSO 4 + Cu Na + 2H 2 O → 2NaOH + H 2

Double Replacement Atoms exchange partners Also called metathesis reactions AX + BY → AY + BX We will look at two types of double replacement Acid-base reactions Precipitation reactions

Acid-Base Reactions Acid – substance that increases the H + concentration in aqueous solutions HCl → H + + Cl - H 2 SO 4 → H + + HSO 4 - HSO 4 → H + + SO 4 2-

Base Increases the OH - concentration NaOH → Na + OH - NH 3 + H 2 O → NH OH -

Neutralization Acids and bases react together to produce a salt (ionic compound) and water HCl + NaOH → NaCl + H 2 O Write a balanced equation for the reaction of hydrobromic acid, HBr, with barium hydroxide, Ba(OH) 2.

Write the balanced equation for the reaction between phosphoric acid, H 3 PO 4, and potassium hydroxide.

Precipitation Reaction Double replacement that forms a precipitate KI (aq) + Pb(NO 3 ) 2 (aq) → PbI 2 (s) + 2KNO 3 (aq)

Example When sodium phosphate and barium nitrate are mixed, a precipitate of barium phosphate forms. Write the balanced equation.

Example When aqueous sodium hydroxide and magnesium nitrate are mixed, a magnesium hydroxide precipitate forms. Write the balanced chemical equation.