CHAPTER 8ACIDS & BASES

IDENTIFYING ACIDS A. IDENTIFYING ACIDS

A. AN ACID IS A COMPOUND THAT PRODUCES

HYDRONIUM IONS (H3O+) WHEN DISSOLVED IN WATER.

B. SOME GENERAL PROPERTIES OF ACIDS INCLUDE

SOUR TASTE, REACTIVITY WITH METALS, AND ABILITY

TO PRODUCE COLOR CHANGES IN INDICATORS.

SOUR TASTE

C. SOUR TASTE

1. MANY OF THE FOODS THAT YOU EAT THAT

TASTE SOUR CONTAIN ACIDS. ALTHOUGH YOU

ACIDS ARE IN THE FOODS WE EAT, YOU

SHOULD NEVER TEST AN ACID BY TASTING IT.

REACTIVITY D. REACTIVITY WITH METALS

1. THE REACTION BETWEEN AN ACID AND A METAL IS AN EXAMPLE

OF A SINGLE REPLACEMENT REACTION.

2. WHEN YOU COVER FOODS THAT CONTAIN TOMATOES WITH

ALUMINUM FOIL, THE FOIL MAY TURN DARK, DEVELOP SMALL

HOLES, AND THE FOOD MAY HAVE A METALLIC TASTE. TOMATOES

CONTAIN CITRIC ACID, WHICH REACTS WITH METALS SUCH AS

ALUMINUM.

COLOR CHANGE

E. COLOR CHANGES IN INDICATORS

1. AN INDICATOR IS A SUBSTANCE THAT CHANGES COLOR

IN THE PRESENCE OF AN ACID OR BASE.

2. A COMMONLY USED INDICATOR IS LITMUS PAPER.

3. BLUE LITMUS PAPER TURNS RED IN THE

PRESENCE OF AN ACID.

BASESB. IDENTIFYING BASES

A. A BASE IS A COMPOUND THAT PRODUCES HYDROXIDE IONS

(OH-) WHEN DISSOLVED IN WATER.

B. SOME GENERAL PROPERTIES OF BASES INCLUDE BITTER

TASTE, SLIPPERY FEEL, AND ABILITY TO PRODUCE COLOR

CHANGES IN INDICATORS. BASES USUALLY DO NOT REACT

WITH METALS.

TASTE

C. BITTER TASTE

1. MANY OF THE FOODS THAT YOU EAT THAT TASTE

BITTER ARE BASES.

2. EXAMPLES OF THESE WOULD BE UNSWEETENED

CHOCOLATE AND LIQUID MEDICATIONS. MANY

TIMES FRUIT FLAVORINGS ARE ADDED TO MASK THE

TASTE OF BASIC SOLUTIONS.

FEELD. SLIPPERY FEEL

1. MANY ITEMS THAT YOU TOUCH ON A DAILY BASES FEEL SLIPPERY.

THIS SLIPPERY FEEL IS DUE TO THE PRODUCT CONTAINING BASES.

2. EXAMPLES OF THESE WOULD BE SOAP AND MANY CLEANING

PRODUCTS. ALSO, ROCKS THAT FEEL SLIPPERY ARE DUE TO WATER

DISSOLVING COMPOUNDS TRAPPED IN THE ROCKS WHICH PRODUCE

A BASIC SOLUTION.

COLOR

E. COLOR CHANGE IN INDICATORS

1. BASES TURN RED LITMUS PAPER BLUE. THE

LITMUS PAPER WILL CHANGE BACK TO RED IF

YOU DROP AN ACIDIC SOLUTION ON IT.

NEUTRALIZATION & SALTSC. NEUTRALIZATION AND SALTS

A. NEUTRALIZATION IS A REACTION BETWEEN AN

ACID AND A BASE.

B. DURING A NEUTRALIZATION REACTION BETWEEN

AN ACID AND A BASE WATER AND SALT ARE

PRODUCED.

PROTONSD. PROTON DONORS AND ACCEPTORS

A. ACIDS CAN BE DEFINED AS PROTON DONORS, AND BASES CAN BE

DEFINED AS PROTON ACCEPTORS.

1. ACIDS LOSE PROTONS.

2. BASES ACCEPT PROTONS.

3. WATER IS NEUTRAL. IN A REACTION WATER CAN ACT LIKE

AN ACID OR A BASE. IN SOME CASES WATER WILL ACCEPT

A PROTON AND BE A BASE, AND IN SOME CASES WATER

WILL LOSE A PROTON AND BE AN ACID.

STRENGTHS

E. STRENGTH OF ACIDS AND BASES

A. ONE WAY TO DESCRIBE THE STRENGTH OF AN ACID OR

BASE IS TO DETERMINE THE CONCENTRATION OF HYDRONIUM OR

HYDROXIDE IONS PRESENT IN A SOLUTION. ANOTHER WAY IS

TO DESCRIBE HOW READILY THOSE HYDRONIUM IONS OR

HYDROXIDE ION FORMED.

PH SCALEF. THE PH SCALE

A. CHEMISTS USE A NUMBER SCALE FROM 0 TO 14 TO

DESCRIBE THE CONCENTRATION OF HYDRONIUM IONS IN A

SOLUTION.

B. A PH OF 7 INDICATES A NEUTRAL SOLUTION.

C. A PH LESS THAN 7 INDICATES AN ACID.

D. A PH GREATER THAN 7 INDICATES A BASE.

ELECTROLYTESG. ELECTROLYTES

A. AN ELECTROLYTE IS A SUBSTANCE THAT IONIZES OR

DISSOCIATES INTO IONS WHEN IT DISSOLVES IN WATER.

B. THE RESULTING SOLUTION CAN CONDUCT ELECTRIC

CURRENT.

C. STRONG ACIDS OR BASES ARE STRONG ELECTROLYTES

BECAUSE THEY DISSOCIATE OR IONIZE ALMOST COMPLETELY

IN WATER.