Chapter 14 & 15.1 Acids, Bases, and pH

Section 14.1 Acids & Bases

Litmus Acids and bases cause certain dyes to change color. These dyes are often used to indicate whether a substance is an acid or base. The most common dye is called litmus.

Litmus Indicators Red Litmus Blue Litmus Acidic solution Stays red Turns red Neutral solution Stays blue Basic solution Turns blue Bases turn red litmus paper blue Acids turn blue litmus paper red

Acids & Bases + Metals Acids react with many metals to produce hydrogen gas. Bases do not commonly react with metals.

Acids Can Cause Damage Calcium carbonate is the major component in limestone and marble. In the prescience of acids in the environment, marble and limestone sculptures and buildings can be damaged or destroyed.

Acid Rain

What is an Acid? An acid is a substance that produces hydronium ions (H3O+) when it dissolves in water. In an acid, a hydrogen ion is transferred to a water molecule. In an acid, any hydrogen atom that can be transferred to water is called an acidic hydrogen.

Ionization Ionization is the process of forming ions in solution. Acids ionize to form ions in water allowing the solution to conduct electricity. Acids are electrolytes.

Base A base is a substance that produces hydroxide ions ( OH- ) when it dissolves in water.

Acidic & Basic Anhydrides An anhydride is a compound that does not contain any water. Acidic anhydrates are nonmetal oxides that react with water to form acids. Basic anhydrates are metal oxides that react with water to form bases.

Everyday Acids & Bases ACIDS BASES lemons soap vinegar bleach coffee antacids TEXTBOOK PAGE 496

Properties of Acids & Bases Taste sour Taste bitter Reacts with metals to produce hydrogen gas feel slippery or soapy reacts with limestone (CaCO3) to produce carbon dioxide Turn blue litmus paper red.  Turn red litmus paper blue. Turn phenolphthalein colorless. Turn phenolphthalein pink.

Section 14.2 Strength of Acids & Bases

Strong Base A strong base completely dissociates into ions when dissolved in water. The strength of an acid is based on the percentage of formula units dissociated.

Strong Bases Strong bases are all hydroxides of group 1, the alkali metals, and group 2, the alkaline earth metals.

Strong Acid A strong acid completely ionizes in water.

Weak Base A weak base only partially ionizes (dissociates) in solution.

Weak Acid A weak acid only partially ionizes in solution. The molecular structure of a weak acid determines the extent to which the acid ionizes in water.

Strength is not Concentration The terms weak and strong are used to compare the strengths of acids and bases. The terms concentrated and dilute are used to describe the concentration of solutions.

Strong Acids & Bases

pH Scale The pH scale is a convenient way to describe the concentration of hydronium ions in acidic solutions as well as the hydroxide ions in basic solutions. Some basic solutions are also called alkali solutions.

pH Scale pH is a mathematical scale in which the concentration of hydronium ions (H3O +) in a solution is expressed as a number from 0 to 14.

pH Scale The pH value is the negative of the exponent of the hydronium ion concentration.

pH Scale ex: A solution with a hydronium ion concentration 10-11 M has a pH of 11. Ex: A solution with a pH of 4 has a hydronium concentration of 10-4 M.

pH Scale You can think of hydronium and hydroxide ions as being on a sliding scale: as the concentration of one increases, the concentration of the other decreases. Acidic solutions contain more hydronium ions than hydroxide ions, while basic solutions contain more hydroxide ions than hydronium ions.

pH Scale If the pH of a solution is 3, the hydronium concentration is 10-3 M. This means that the hydroxide ion concentration is 10-14 / 10-3 M which is 10-14 - ( -3) M or 10-11 M .

Using Indicators to Measure pH Indicators change color depending on the pH of the solution. Universal Indicator

Natural Indicators Hydrangea

Indicator Art… As a base is wiped over the paper which already has the indicator phenolphthalein on it the drawing changes to pink.

pH of Common Substances

Why is Water Neutral? Water has a pH of 7 Hydronium concentrations (10-7) M and hydroxide concentrations (10-7)M are equal.

Section 15.1 Acid and Base Reactions

Neutralization Reaction A neutralization reaction is a reaction of an acid and a base in an aqueous solution to produce water and a salt. ex: HCl + NaOH  H2O + NaCl (Acid) + (Base)  (Water) + (Salt)

Ions in Neutralization Reaction   H+   +  OH-   H2O

Titration Video (0:52)

Rainbow Connection Video (3:43)