Unit A 2.4 Acids and Bases

Acids & Bases Acids - compounds that dissolve in water to form a solution , pH<7 Bases - compounds that dissolve in water to form a solutions, pH>7 pH - indicates whether a substance is an acid or a base measures the [H+] Buffer - substance that keeps the pH at a constant, despite the addition of acids or bases .i.e. your stomach

Acids & Bases Indicators - chemicals that determine if a solution is an acid or a base .I.e. Litmus paper, derived from Lichen ACID BASE RED BLUE Acid -> Red stays red, blue turns red Base -> Blue stays blue, red turns blue Neutral -> Blue stays blue, red stays red

Acids & Bases Universal Indicators - change color at a variety of pH levels pH scale - measure of acidity = [H+] one interval increase on the pH scale = 10x more acidic or basic

pH Scale http://ic.ucsc.edu/~wxcheng/envs23/lecture17/pH_meter.jpg

Properties of Acids & Bases Property Acid Base Taste Sour Bitter Touch Wet Slippery Reaction with metals Metal corrodes H2 bubbles form No reaction Litmus indicator Red Blue Electrical conductivity (in solution) conductive Conductive pH of solution <7 >7

Naming Acids Recognizing Acids H appears on the left side of the formula hydrochloric acid - HCl(aq) -COOH - organic acid group found in the chemical formula ethanoic acid - CH3COOH(aq)

Naming Acids Naming according to IUPAC State of the compound followed by the name HCl(aq) - aqueous hydrogen chloride H2SO4(aq) - aqueous hydrogen sulfate Other naming systems prior to IUPAC For acids containing H and a non-metallic element start with “hydro”, end with “ic” HCl(aq) - hydrochloric acid HF(aq) - hydrofluoric acid

Naming Acids For acids containing oxygen name is based on the anion if the anion ends in “ate”, then the acid will end in “ic” H2SO4(aq) - Sulfate -> derived from sulfur, then sulfuric acid H3PO4(aq) - Phosphate -> derived form phosphorous, then phosphoric acid HNO3(aq) - Nitrate -> derived from nitrogen, then nitric acid if the anion ends in “ite”, then the acid will end in “ous” H2SO3(aq) - Sulfite -> derived from sulfur, then sulfurous acid HNO2(aq) - Nitrite -> derived from nitrogen, then nitrous acid

Recognizing Bases OH- with a metal or ammonium = base NaOH - sodium hydroxide Other bases are difficult to identify & will be studied in more advanced chemistry

Neutralization Reactions of acids and bases together to cancel out each others properties

Acid Rain (Precipitation) Oxides of carbon, nitrogen and sulfur produced from burning organic materials react with water in the air to form acid rain.

Acid Precipitation

Homework: Read Science 10 Text p.62 – 69 & 70-75 WB pg 70-71 ALL Section Review text pg 76-77 A2.0 1-34