Acids & Bases Hammer & Rundell

Review: How Do We Set Up an Experiment? Constants (things that remain the same for all test groups) Independent Variable (manipulated or controlled by the experimenter – cause) Dependent Variable (depends on the independent variable – effect) (used as a standard of comparison) Control

Graphing the Results Dependent (y) – Each finger in the group depends on the others. Independent (x) – Thumb stands alone relying on no one but himself.

Acids and Bases are common Citrus fruits Vitamin c Vinegar Household cleaners Stomach acid Soft Drinks Bases Antacids Household cleaners Soap

Acids and Bases Classifying based on properties Sour Corrosive Bases Bitter Slippery

Another way to look at acids Acids donate hydrogen ions when dissolved in water Bases donate hydroxide ions when dissolved in water. HCl  H+ + Cl- (acid) NaOH  Na+ + OH- (base)

Practice Identify as acid or base based on their ionization Ca(OH)2  Ca2+ + OH- HBr  H+ + Br-

Acids Ionize in Water: HBr  H+ + Br- The hydrogen will bond with a water molecule to produce hydronium. H30+

Strength of Acids & Bases The strength of acids & bases is determined by how many hydrogen or hydroxide ions have been produced. Lots of hydrogen ions = strong acid Lots of hydroxide ions = strong base

Measuring Strength of Acids & Bases We measure the strength of acids and bases using the pH scale. Acids range from 0 to 7 Bases range from 7 to 14 7 is Neutral

pH and Indicators Indictors are chemicals used to determine the pH of a substance.

Acids and Bases neutralize each other HCl + NaOH  H2O + NaCl Acid base neutral  + Acids and bases combine to form water and a salt.

Our Environment We have all heard of acid rain. It forms when pollutants such as sulfur oxides combine with water to form sulfuric acid. Sulfur oxides + water  acid rain

Question 1 Where on the pH scale are the acids? pH Scale 0 7 14

Question 2 The directions on a can of oven cleaner say that you must use gloves. The cleaner is slippery and turns litmus paper blue. It is probably a _____. A. Acid B. Base C. Salt D. isotope

Question 3 A beaker contains 100 mL of a solution with a pH = 3. One hundred mL of a second unknown solution is added to the first solution and stirred. The pH of the mixture is now 2.5. The second solution A. has a high concentration of hydroxide ions B. is neutral C. is a strong acid D. is a salt

Question 4 Which of the following is a base? A. a substance with a pH = 6 B. A solution with more hydrogen ions than hydroxide ions C. Ba(OH)2 D. NaBr

Question 5 Acid rain is the result of water combining in the atmosphere with sulfur oxides to form sulfuric acid. Which of the following might occur in a region that has acid rain? A. Lakes have a lower pH than normal B. Plants die C. Rocks weather D. All of the above