Unit 3 Acids and Bases

Common Acids Sulfuric Acid H2SO4 Nitric Acid HNO3 Phosphoric Acid H3PO4 Hydrochloric Acid HCl Acetic Acid CH3COOH Carbonic Acid H2CO3 Battery acid Used to make fertilizers and explosives Food flavoring Stomach acid Vinegar Carbonated water

Sulfuric Acid, H2SO4 Sulfuric acid is the most commonly produced industrial chemical in the world. Uses: petroleum refining, metallurgy, manufacture of fertilizer, many industrial processes: metals, paper, paint, dyes, detergents Sulfuric acid is used in automobile batteries. Compound produced in the largest quantity in the industrial world and is one of the oldest chemical compounds known Production — starts with elemental sulfur obtained through a technique called the Frasch process, in which very hot water forces liquid sulfur out of the ground in nearly pure form. Sulfuric acid is produced by the reaction of sulfur dioxide with oxygen in the presence of vanadium(V) oxide (the contact process), followed by the absorption of the sulfur trioxide in concentrated sulfuric acid to produce oleum. Uses — to make fertilizers and potash, one of the major ingredients in fertilizers H2SO4 “oil of vitriol”

Nitric Acid, HNO3 Nitric acid stains proteins yellow (like your skin). Uses: make explosives, fertilizers, rubber, plastics, dyes, and pharmaceuticals. HNO3 For making fertilizers. About 75% of the nitric acid produced in the United States is used in the manufacture of fertilizers. Ammonium nitrate is the most important nitrate so used, and is readily manufactured in plants using the combined Haber-Ostwald processes. Sodium nitrate and potassium nitrate are also used as fertilizer ingredients. For making explosives. Many modern explosives are made directly or indirectly from nitric acid. The acid itself is not an explosive, but many of the compounds derived from it form the most violent explosives known. Among these are nitroglycerine, smokeless powder, and TNT. For making dyes. Nitric acid reacts with several products obtained from coal tar, forming nitro compounds. One of these coal tar products, benzene, reacts with nitric acid to form nitrobenzene, C6H5NO2. Aniline, C6H5NH2, a compound used in making different dyes, is made by reducing nitrobenzene with hydrogen. For making plastics. Cotton which consists mainly of cellulose, (C6H10)5)n, is treated with a mixture of nitric acid and sulfuric acid to make nitrocellulose plastics. A variety of products is formed, depending on the amount of nitric acid used, the temperature, and the length of time the acid is allowed to act on the cellulose. Manufacturers use sulfuric acid to absorb the water that is formed in the reaction. Celluloid, pyroxylins, photographic film, and many other products are made from such nitrocellulose plastics. Modern Chemistry Metcalfe, Williams, and Catska (1966) pg. 491 “aqua fortis”

Hydrochloric Acid, HCl HCl(g) + H2O(l) HCl(aq) The stomach produces HCl to aid in the digestion of food. Uses: For ‘pickling’ iron and steel. Pickling is the immersion of metals in acid solution to remove surface impurities. A dilute solution of HCl is called muriatic acid (available in many hardware stores). Muriatic acid is commonly used to adjust pH in swimming pools and in the cleaning of masonry. HCl(g) + H2O(l) HCl(aq) hydrogen chloride water hydrochloric acid

Common Bases Name Formula Common Name Sodium hydroxide NaOH lye or caustic soda Potassium hydroxide KOH lye or caustic potash Magnesium hydroxide Mg(OH)2 milk of magnesia Calcium hydroxide Ca(OH) 2 slaked lime Ammonia water NH3 H2O household ammonia Bases – Bases are ionic compounds that contain the hydroxide ion and a metal cation and have the general formula M(OH)n . – When a base reacts with an acid, it accepts a proton (H+) and is therefore called a proton acceptor. – Aqueous ammonia solution is also a common base. – Replacing a hydrogen atom of NH3 with an alkyl group results in an amine (RNH2), which is also a base. Amines have pungent odors. . NH4OH

Acids properties Conduct electricity; are electrolytes (strong acids) Change blue litmus to red Have a sour taste React with bases to neutralize their properties React with active metals to liberate hydrogen pH values <7

Acids Acids are defined as: Substances which ionize to form hydrogen ions (H+) in aqueous solution. (Arrhenius) Substances that act as proton donors, H+ (Bronsted-Lowry) or as electron-pair acceptors (Lewis) Examples HCl, H2SO4

Bases properties Base properties Conduct electricity ,are electrolytes (strong bases) Change red litmus to blue Have a slippery feeling (like soap) React with acids to neutralize their properties pH values >7

Bases Bases are defined as: Substances which ionize to form hydroxide ions OH(-) in aqueous solution Substances that act as proton receptors (Bronsted-Lowry) or as electron-pair donors (Lewis) Examples: NH3OH, NaOH, CaCO3 , NaHCO3 (baking soda) AMMONIAcleaner

pH Scale lemon juice 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH Acidic Neutral Basic vinegar d water baking soda ammonia detergent The pH scale is used to measure how acidic or basic a liquid is. pH measures the concentration of hydrogen ions (H+) and hydroxide ions (OH-). The scale goes from 0 through 14. Distilled water is 7, so is called neutral.

Indicators An indicator is a large organic molecule that works somewhat like a "color dye." Indicator Acid Base Red litmus paper Stays same Turns blue Blue litmus paper Turns red Bromophenol blue Yellow Stays blue Phenolphtalein Colorless Pink

Natural indicators There are natural indicators for acids and bases, and we may find them in our kitchen or garden! Red rose flowers Bougainvillea flowers Red cabbage Blue berries

Practice: identifying acid and bases 1) HCl + H2O  H3O+ + Cl– H+ HCl is the acid because it is donating a H+ to H2O H2O is the base because it is accepting a H+ from HCl Cl- is the conjugate base because it’s what’s left after the acid donates a H+ H3O+ is the conjugate acid because it’s what’s left after the base accepts a H+

Practice: identifying acid and bases 2) CN- + H2O  OH- + HCN H+ H2O is the acid because it is donating a H+ to CN- CN- is the base because it is accepting a H+ from H2O OH- is the conjugate base because it’s what’s left after the acid donates a H+ HCN is the conjugate acid because it’s what’s left after the base accepts a H+

Practice: identifying acid and bases 3) OH- + HI  H2O + I- H+ Donates a H+ acid The acid can donate a H+ and its chemical formula usually has a H at the beginning Classwork :handout conjugate acids and bases