4.5 Three Examples of Chemical Reactions: Combustion, Alkali Metals, and Halogens

combustion reaction

a type of chemical reaction in which a substance combines oxygen to form one or more oxygen-containing compounds; the reaction often causes the evolution of heat and light in the form of a flame

fuel, oxidant/oxidizer, combustion temperature

3 requirements for a combustion reaction

carbon dioxide, water

Compounds containing carbon and hydrogen or carbon, hydrogen, and oxygen always form ________________ and ________ upon complete combustion.

C

Any _ in combustion reacts with O₂ to produce carbon dioxide.

H

Any _ in combustion reacts with O₂ to form water.

2M + X₂ → 2MX

reaction when alkali metals (M) react with halogens (X)

• e.g. 2Na(s) + Cl₂(g) → 2NaCl(s)

more

Each successive alkali metal reacts _____ (more/less) vigorously with the same nonmetal.

2M(s) + 2H₂O(l) → 2M⁺(aq) + 2OH^-(aq) + H₂(g)

reaction when alkali metals (M) react with water to form dissolved alkali metal ion, hydroxide ion, and hydrogen gas

• highly exothermic, becomes more explosive as we move down the column from one metal to the next

2M + nX₂ → 2MX_n

reaction when halogens (X) react with many metals to form metal halides

• e.g. 2Fe(s) + 3Cl₂(g) → 2FeCl₃(s)

H₂(g) + X₂ → 2HX(g)

reaction when halogens (X) react with hydrogen to form hydrogen halides

HX

hydrogen halide, contains covalent bonds like all compounds that form between 2 nonmetals, forms acids when combined with water

interhalogen compounds

compounds formed when halogens react with each other (e.g. Br₂(l) + F₂(g) → 2BrF)