Types of Chemical Reactions Chemical Equations and Reactions

Types of Chemical Reactions { Chemical Equations and Reactions In this part of chapter 8 we want to learn how to identify the type of chemical reaction that takes place, as well as how to predict what products will form as the result of the chemical reaction.

There are 5 main types of chemical reactions. 1. Synthesis 2. Decomposition 3. Single Displacement (Replacement) 4. Double Displacement (Replacement) 5. Combustion

Synthesis (Composition) Reactions Two or more substances combine to form a new compound. A + X AX Reaction of elements with oxygen and sulfur Reactions of metals with Halogens Synthesis reactions with Oxides There are others not covered here!

Decomposition Reactions A single compound undergoes a reaction that produces two or more simpler products. AX A + X Decomposition of: Binary compounds Metal carbonates Metal hydroxides Metal chlorates Oxyacids 2 H₂O(I ) 2 H₂(g) + O₂(g) Ca. CO₃(s) Ca. O(s) + CO₂(g) Ca(OH)₂(s) Ca. O(s) + H₂O(g) 2 KCl. O₃(s) 2 KCl(s) + 3 O₂(g) H₂CO₃(aq) CO₂(g) + H₂O(I )

Single Replacement Reactions A + BX BX + Y Replacement of: AX + B BY + X Metals by another metal Hydrogen in water by a metal Hydrogen in an acid by a metal Halogens by more reactive halogens

By understanding how reactions work, we can predict what products will form.

Answers from previous slide Fe(s) + Cu. SO₄(aq) → Fe. SO₄(aq) + Cu(s) 2 KCl + Pb <-> Pb. Cl 2 + 2 K 2 Al(s) + 6 HCl(aq) = 2 Al. Cl 3(aq) + 3 H 2(g)

Double Replacement Reactions The ions of two compounds exchange places in an aqueous solution to form two new compounds AX + BY AY + BX One of the compounds formed is usually a precipitate, an insoluble gas that bubbles out of the solution, or a molecular compound, usually water.

Answers from the previous slide 2 Ag. NO 3 + K 2 Cr. O 4 -> Ag 2 Cr. O 4 + 2 KNO 3 2 KI + Pb(NO 3)2 -> 2 K(NO)3 + Pb. I 2 Na. CN + H 2 SO 4 -> HCN + Na 2 SO 4 Ca(OH)2 (s) + 2 HCl(aq) -> Ca. Cl 2(aq) + 2 H 2 O (l)

Combustion Reactions A substance combines with oxygen, releasing a large amount of energy in the form of light and heat. Reactive elements combine with oxygen P₄(s) + 5 O₂(g) P₄O₁₀(s) (This is also a synthesis reaction) The burning of natural gas, wood, gasoline, C₃H₈(g) +5 O₂(g) 3 CO₂(g) + 4 H₂O(g)

Self Assessment – Identifying Types of Chemical Reactions, Predicting Products &Writing Balanced Chemical Equations 1. nitrogen dioxide 2. glucose (C 6 H 12 O 6) + O 2 → 3. silver nitrate + copper 4. sodium phosphate + potassium hydroxide 5. hydrogen + oxygen

Answers 1. __2_ NO 2 → ___ N 2 + _2_ O 2 (decomposition) 2. ___ C 6 H 12 O 6 + __6_ O 2 → _6_ CO 2 + _6_ H 2 O (combustion) 3. _2_ Ag. NO 3 + ___Cu → ___ Cu(NO 3)2 + __2_ Ag (single replacement) 4. __ Na 3 PO 4 + _3_ KOH → ___K 3 PO 4 + _3_ Na. OH (double replacement) 5. __2__ H 2 + ____O 2 -> __2__H 2 O (synthesis)