Acids and Bases Chapter 10 Acids and Bases
Acids and Bases. . Chapter 10
Acids and Bases are chemical opposites and they both have contrasting properties. Acids are immediately recognizable from their chemical formula in that hydrogen (H) will be the first element listed in the formula. For Example: HCl, H 2 SO 4, H 3 PO 4, etc. Acids almost always have names that end in “__ic acid” For example: HCl = hydrochloric acid H 2 SO 4 = sulfuric acid
Acids will liberate H+ ions when dissolved in water. It comes from the acidic hydrogen in the formula, which is listed first in the formula. For example: HCl + H 2 O → H+ + Cl- + H 2 O Subsequently, each liberated hydrogen ion combines with one molecule of water to form a hydronium ion H + + H 2 O → H +3 O
Other properties of acids: • Acids are corrosive • Acids taste sour • Acids will neutralize bases • Acids will turn blue litmus paper to red
Characteristics of bases: Bases are recognizable from their formula which usually has a metal followed by hydroxide (OH). For example: Na. OH, KOH, Ca(OH)2 Therefore, the name of a typical base has the name of the metal followed by hydroxide: KOH = potassium hydroxide Mg(OH)2 = magnesium hydroxide In aqueous solution, bases will absorb hydrogen ions
Properties of bases: • • Bases taste bitter or chalky Bases will neutralize acids Bases feel slippery Bases turn red litmus paper to blue Strong bases • are formed from metals of Groups 1 A (1) and 2 A (2). • include Li. OH, Na. OH, KOH, and Ca(OH)2.
The strength of an acid or base is measured by p. H values rage from ZERO to 14. The more acidic a substance or solution, the lower the p. H value. The more basic the substance or solution, the higher the p. H value. Any substance or solution having a p. H of exactly 7. 00 is NEUTRAL.
The p. H of a solution • is used to indicate the acidity of a solution. • has values that usually range from 0 to 14. • is acidic when the values are less than 7. • is neutral with a p. H of 7. • is basic when the values are greater than 7. In order to raise the p. H value of a solution, you need to add base. In order to lower the p. H value of a solution, you need to add acid.
See Page 343
The p. H of solutions can be determined using a) p. H meter. See Page 339 b) p. H paper. c) indicators that have specific colors at different p. H values.
However, if a solution is buffered, addition of either acid or base will not change the p. H. A “BUFFER” is a substance, which, when added to a solution will make that solution resist p. H change.
See Page 345 - 346 Neutralization Equations In the equation for neutralization, an acid and a base produce a salt and water. acid base salt water HCl + Na. OH Na. Cl + H 2 O 2 HCl + Ca(OH)2 Ca. Cl 2 + 2 H 2 O 13
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