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Acids & Bases . Acids. sour tasting, water-soluble extremely reactive and combine with many other substances. Acids. Acid solutions are good conductors of electricity. This is because they are ionic compounds.
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Acids • sour tasting, water-soluble • extremely reactive and combine with many other substances.
Acids • Acid solutions are good conductors of electricity. • This is because they are ionic compounds. • All acids contain hydrogen atoms and when acids dissolve in water, they release hydrogen ions (H+)
Acids • e.g. Hydrochloric acid (HCl(aq)) consists of hydrogen ions (H+) and chlorine ions (Cl-) dissolved in water. HCl(aq) H+(aq) + Cl-(aq) • Common acids are easily recognized because their formulas begin with hydrogen. (H2SO4)
Naming Acids • If acid is made of only a hydrogen and one other element, use the prefix "hyrdro", the stem of the element, and the suffix "ic." • For example, HCl is hydrochloric acid.
Naming Acids • If acid is made of a hydrogen ion and a polyatomic ion: • start with the name of the ion. • Subtract the "ate" or "ite" from the end. • If it was an "ate" add the suffix "ic" and if it was an "ite" add the suffix "ous." Then finish by adding acid. • For example, H2SO4 (a hydrogen and a sulfate ion) is named Sulfuric acid.
Bases • bitter tasting, water-soluble, feel slippery in aqueous solution.
Bases • good conductors of electricity because they release hydroxide ions (OH-) when they dissolve in water. • e.g. Sodium hydroxide (NaOH) produces sodium ions (Na+) and hydroxide ions (OH-) when it dissolves in water. NaOH(aq) Na+(aq) + OH-(aq)
Bases • Most bases are compounds that contain the hydroxide ion (OH-). • Whenever you see an ionic formula with a hydroxide, you know it will be a base. (NaOH)
The pH Scale • A method of classifying substances as acids, bases or neutral • Based on the concentration of H+ ions in a solution Neutral Bases Acids 7 0 14
Acid-Base Indicators • Indicator: a chemical that turns a different colour in contact with an acid and/or a base.
Litmus Paper • Turns red under acidic conditions • Turns blue under basic conditions
Bromothymol Blue • Works best for weak acids and bases
Neutralization Reaction • chemical reaction that occurs between an acid and a base (double displacement) • products are a salt and water Acid + Base Salt + Water (H+) + (OH-) Salt + H2O • Salt- a substance formed from the metal cation of a base and the anion of an acid
Antacids • Stomach produces HCl with pH of 1.5 (for digestion) • Acid can irritate stomach lining or esophagus • Antacids neutralize stomach acid • Ex. Milk of Magnesia 2HCl + Mg(OH)2 2H2O + MgCl