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Download acids and bases - IDS-chem2-Rn-10
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ACIDS AND BASES Angela M. Colonia and Kristine Marie C. Pa-alisbo Physical and Chemical behavior Acids • corrosive to metals • change litmus to red • become less acidic when mixed with bases • release a hydrogen ion into water (aqueous) solution • neutralize bases in a neutralization reaction Bases • change litmus to blue • become less basic when mixed with acids • release a hydroxide ion into water solution • neutralize acids in a neutralization reaction • denature protein How do we differentiate them? Acids • when added to water produces hydrogen ions [H+] • tastes sour Bases • when added to water produces hydroxide ions [OH-] • feels slippery • tastes bitter Identifying the strength Strong acids • completely dissociate in water, forming H+ and an anion •uses only one arrow (→) is required since the reaction goes virtually to completion Weak acids • Incompletely ionized acids because there is a smaller concentration of ionized hydrogens available in the solution • partially dissociates in water to give H+ and the anion • uses the double arrow because equilibrium exists between the dissociated ions and the undissociated molecule Strong Bases • dissociate 100% into the cation and OH- (hydroxide ion) •They are hydroxides of Groups I and II. The hydroxides of Group II metals produce 2 mol of OH- ions for every mole of base that dissociates. These hydroxides are not very soluble, but what amount that does dissolve completely dissociates into ions. Weak bases • due to the presence of an amino group -(NH2) attached to an organic compound • They are anions of weak acids. • They do not furnish OH- ions by dissociation. They react with water to furnish the OH- ions. • When reacts with water the OH- comes from the water and the remaining H+ attaches itself to the weak base, giving a weak acid as one of the products. How are they quantified 2 ways: • pH - expresses how acidic or alkaline a water solution is • titration - rhymes with "tight nation," and refers to a commonly used method of (usually) finding the concentration of an unknown liquid by comparing it with a known liquid pH Indicators • in the form of plant pigments known as antocyanines - which change color over different pH ranges, depending on source. Common uses/applications • manufacture of other chemicals - Fertilizers, synthetic fabrics, pigments, petroleum, iron and steel, explosives, dyes, plastics, pesticides, soaps and detergents, paper, film, and many other chemicals • various other purposes - cleaning surfaces, refining oil and sugar, electroplating metals, and treating food products
