ACIDS AND BASES

ACIDS & BASES

Acids are substances that produce hydrogen ion in solution. (H+

(aq))

Bases are substances that produce hydroxide ions in solution. (OH-

(aq))

ACIDS BOTH BASES

Sour tasting Produce H+ ions Turns blue litmus red pH 0-6 React with metals to produce H2 (g)

Clear and colorless in solution Can be dangerous

Bitter tasting Produce (OH)- ions Turns red litmus paper blue pH 8-14

EXAMPLES ACIDS BASES -Lactic acid in milk & sore - soaps, drain & window

muscles cleaners -Hydrochloric acid in stomach - lidocaine-dental

anaesthetic

pH Scale

Measures acidity or basicity of solutionspH scale is measured from pH = 0-14

pH < 7 – AcidicpH = 7 - NeutralpH > 7 – Basic

Very high and low pH solutions are harmful

Water is neutral, because H+ and OH- ions balance

H2O H+ + OH-

Indicators substances that change color as the concentration of H+ or OH- ions changes.they indicate pH

Examples: litmus paper, phenolphthalein, universal indicator

Blue Litmus paper turns red – AcidRed Litmus paper turns blue - Base

Most indicators work only over a short range of pH values.

Universal indicator (or pH paper) contains a number of indicators that change color at different pH values.

REACTIONS

Metals react with acids to form hydrogen gas and a salt.

Ex. Mg(s) + 2HCl (aq) H2(g) + MgCl2(aq)Magnesium metal + hydrochloric acid hydrogen gas + magnesium chloride salt

Acids react with bases to form water and a salt. This process is called neutralization.

Ex. HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)

Hydrochloric acid + sodium hydroxide base sodium chloride salt + water

[Note that this is a double displacement reaction]

Tomorrow: ACID/BASES LAB