Presentation on theme: "ACIDS AND BASES. ACIDS & BASES Acids are substances that produce hydrogen ion in solution. (H + (aq) ) Bases are substances that produce hydroxide ions."— Presentation transcript:
ACIDS & BASES Acids are substances that produce hydrogen ion in solution. (H + (aq) ) Bases are substances that produce hydroxide ions in solution. (OH - (aq) ) ACIDSBOTHBASES Sour tasting Produce H + ions Turns blue litmus red pH 0-6 React with metals to produce H 2 (g) Clear and colorless in solution Can be dangerous Bitter tasting Produce (OH) - ions Turns red litmus paper blue pH 8-14
pH Scale Measures acidity or basicity of solutions pH scale is measured from pH = 0-14 pH < 7 – Acidic pH = 7 - Neutral pH > 7 – Basic Very high and low pH solutions are harmful Water is neutral, because H + and OH - ions balance H 2 O 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 – Acid Red 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) H 2(g) + MgCl 2(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) + H 2 O (l) Hydrochloric acid + sodium hydroxide base sodium chloride salt + water [Note that this is a double displacement reaction] Tomorrow: ACID/BASES LAB