Acids and Bases

Acids Acids are compounds that add (H+) ions to water when in a solution.   In Water HCl: a very strong acid. In water it breaks up (dissociates) and adds H+ to the water. H+ Cl-

Hydronium ions As acids dissolve in water,(H+) ions interact with water molecules to produce hydronium ions (H3O+)

Bases Bases are compounds that add (OH-) ions to water when in a solution. (OH-) ions are called hydroxide ions In water   NaOH: a very strong base. In water it breaks up (dissociates) and adds OH- to the water. H+ O2- Na+

Common Acids Many foods are acidic: Tomatoes Lemons Oranges Limes Apples vinegar Acids taste sour and feel squeaky when you rub them between your fingers

Common Bases Many cleaners are basic: Soap Bleach ammonia (Windex)   Bases taste bitter and feel slippery when you rub them between your fingers

Are antacids acids or bases? Question #1 Are antacids acids or bases? Why?

Safety Acids are corrosive! They can burn your skin or eyes. Bases are caustic! They can burn your skin or eyes.   Why do you think the safety sign for acids and bases is the same sign?

Other Terms Strong acids and bases—ionize (dissolve) completely in water, adding many ions to the water   Weak acids and bases—do not ionize (dissolve) completely in water, adding fewer ions to the water.

The pH Scale

Litmus Paper Acids are indicated by a Red color. If Red litmus paper is dipped in an acid it will stay Red If Blue litmus paper is dipped in an acid it will turn Red

Litmus Paper Bases are indicated by a Blue color. If Blue litmus paper is dipped in a base it will stay blue If Red litmus paper is dipped in a base it will turn Blue

Question #2! What is the difference between the pH scale and litmus paper?

Acid-Base Reactions: Neutralization Neutralization Reaction: When acids and bases are mixed together, they neutralize each other. If an equal concentration of acid and base are mixed, they make a neutral solution of a salt and water   HCl + NaOH —> H2O + NaCl Acid Base Water Salt H+ O2-

What is a Salt? A compound formed when the negative ions from an acid combine with the positive ions from a base

Titration (Lab Process) The lab process where this is studied is called titration and it uses a piece of glassware called a buret.

Acid Rain Acid Rain: Plants and animals need water close to neutral (pH 7) to survive. Due to pollution from industries and cars, rain in certain areas can be acidic. Rain less than pH 5.6 is called acid rain. Acid rain can kill plants, cause asthma, and other physical problems. Because statues and landmarks are made of limestone (a base), acid rain will also slowly destroy them.  

Acid Rain (cont) The Roman ruins, the pyramids of Egypt, and other treasures of the world are slowly being reacted away by acid rain. More damage has been done in the last century than in the last 2,000 years.

Acid Rain (cont) Why do you think there has been more damage from acid rain in the last 100 years?

Practice

Practice

Practice

Practice

Let’s See What You Know… B D C A E F H J G I

Part II….

Part III A B B B A A