Types of Chemical Reactions

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!

Hydrogen reacting with oxygen Reactions of elements with oxygen Hydrogen reacting with oxygen 2H2(g) + O2(g)  2H2O(g)

Reaction of aluminum and bromine …a metal with a halogen: Reaction of aluminum and bromine 2Al(s) + 3Br2(g)  2AlBr3(s)

Decomposition Reactions A single compound undergoes a reaction that produces two or more simpler substances AX  A + X Decomposition of: Binary compounds 2H2O(l )  2H2(g) + O2(g) Metal carbonates CaCO3(s)  CaO(s) + CO2(g) Metal hydroxides Ca(OH)2(s)  CaO(s) + H2O(g) Metal chlorates 2KClO3(s)  2KCl(s) + 3O2(g) Oxyacids H2CO3(aq)  CO2(g) + H2O(l )

Decomposition of Nitrogen Triiodide 2 NI3(s)  N2(g) + 3 I2(g)

Decomposition of Mercury(II) Oxide Metal oxides decompose with heating… Decomposition of Mercury(II) Oxide 2HgO(s)  2Hg(l ) + O2(g)

Catalyzed Decomposition of Hydrogen Peroxide Some decomposition needs catalysis… Catalyzed Decomposition of Hydrogen Peroxide 2H2O2(l )  2H2O(l ) + O2(g)

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

Redox (short for reduction–oxidation reaction) is a chemical reaction in which the oxidation states of atoms are changed.  Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom, or ion. Reduction is the gain of electrons or a decrease in oxidation state by a molecule, atom, or ion.

Reaction of copper with aqueous silver nitrate A metal replaces another metal (in solution)… Reaction of copper with aqueous silver nitrate Cu(s) + 2AgNO3(aq)  Cu(NO3)2(aq) + 2Ag(s)

A metal replaces another metal (no solution needed!)… The Thermite reaction 2Al(s) + Fe2O3(s)  Al2O3(s) + 2Fe(s)

Reaction of potassium with water An active metal replaces hydrogen in water… Reaction of potassium with water 2K(s) + 2H2O(l )  2KOH(aq) + H2(g)

Magnesium in Hydrochloric Acid A metal replaces hydrogen in an acid… Magnesium in Hydrochloric Acid Mg(s) + 2HCl(aq)  MgCl2(aq) + H2(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 solution, or a molecular compound, usually water.

Lead(II) nitrate reacts with potassium iodide Double replacement forming a precipitate… Lead(II) nitrate reacts with potassium iodide Pb(NO3)2(aq) + 2KI(aq)  PbI2(s) + 2KNO3(aq)

Reaction of Hydrochloric acid and Sodium hydroxide Double replacement forming water… Reaction of Hydrochloric acid and Sodium hydroxide HCl(aq) + NaOH(aq)  NaCl(aq) + H2O(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) + 5O2(g)  P4O10(s) (This is also a synthesis reaction) The burning of natural gas, wood, gasoline C3H8(g) + 5O2(g)  3CO2(g) + 4H2O(g) ______ + O2  CO2 + H2O

Reaction of white phosphorus and oxygen An element burning in oxygen… Reaction of white phosphorus and oxygen P4(s) + 5O2(g)  P4O10(s)

More Reactions With Oxygen 2 Mg(s) + O2(g)  MgO(s) 4 Fe(s) + 3 O2(g)  2 Fe2O3(s) P4(s) + 5 O2(g)  P4O10(s) S8(s) + 8 O2(g)  8 SO2(s)

Hydrogen and oxygen reacting Energy for space travel… Hydrogen and oxygen reacting 2H2(g) + O2(g)  2H2O(g) + energy

Burning of natural gas… Combustion of Propane C3H8(g) + 5O2(g)  3CO2(g) + 4H2O(g)

Combustion of methanol Burning of an alcohol… Combustion of methanol CH3OH(l ) + 2O2(g)  CO2(g) + 2H2O(g)

The Activity Series of the Metals Lithium Potassium Calcium Sodium Magnesium Aluminum Zinc Chromium Iron Nickel Lead Hydrogen Bismuth Copper Mercury Silver Platinum Gold Metals can replace other metals provided that they are above the metal that they are trying to replace. Metals above hydrogen can replace hydrogen in acids. Metals from sodium upward can replace hydrogen in water

The Activity Series of the Halogens Fluorine Chlorine Bromine Iodine Halogens can replace other halogens in compounds, provided that they are above the halogen that they are trying to replace. 2NaCl(s) + F2(g)  2NaF(s) + Cl2(g) ??? MgCl2(s) + Br2(g)  No Reaction ???