INTRODUCTION TO ACIDS & BASESMRS. ARIEL D’ANTON

STUDENT OBJECTIVE

At the end of this lesson, student’s will be able to: Describe acids and bases by identifying similar characteristics

Derive the definition of acids and bases through examination of its properties

Classify solutions as acidic or basic through use of an indicator

DO NOW: 2 MINS

CATEGORIZE THE ITEMS ON THIS SLIDE AS ACIDS OR BASES

IF COMPLETED BEFORE 2 MINS: BRAINSTORM OTHER HOUSEHOLD EXAMPLES OF ACIDS & BASES

ACID / BASE PROPERTIES

ACID BASE

SOUR TASTE*

CAUSES COLOR CHANGE OF ACID/BASE INDICATORS

SOME ACIDS REACT WITH METALS TO FORM HYDROGEN GAS

ACIDS REACT WITH BASES TO FORM SALT AND WATER

CONDUCT ELECTRIC CURRENT

*DANGER: DO NOT TASTE CHEMICALS IN THE LABORATORY

ACID / BASE PROPERTIES

ACID BASE

SOUR TASTE* BITTER TASTE*

CAUSES COLOR CHANGE OF ACID/BASE INDICATORS

CAUSES COLOR CHANGE OF ACID/BASE INDICATORS

SOME ACIDS REACT WITH METALS TO FORM HYDROGEN GAS

DILUTE SOLUTIONS FEEL SLIPPERY

ACIDS REACT WITH BASES TO FORM SALT AND WATER

BASES REACT WITH ACIDS TO FORM SALT AND WATER

CONDUCT ELECTRIC CURRENT CONDUCT ELECTRIC CURRENT

*DANGER: DO NOT TASTE CHEMICALS IN THE LABORATORY

ACID & BASE DEFINITIONS

ACID: ARRHENIUS - SUBSTANCES THAT IONIZE IN WATER TO PRODUCE H+ IONS

BASE: ARRHENIUS – SUBSTANCES THAT IONIZE IN WATER TO PRODUCE OH- IONS

STRONG & WEAK ACIDS

Strong Acids completely dissociate and form H+ ions, where weak acids do not completely dissociate.

PH

pH: MEASUREMENT OF HYDRONIUM ION CONCENTRATION (measure of acidity) pH=-log[H+]

[H+]=10-pH

7 14

0STRONG ACID

STRONG BASE

STRONG/WEAK BASES Strong bases completely ionize in water to form OH ions, where weak bases do not

completely ionize in water.

POH

pOH: MEASUREMENT OF HYDROXIDE CONCENTRATION (measure of alkalinity/basicity) pOH=-log[OH-]

[OH-]=10-pOH

0STRONG BASE

STRONG ACID

7 14

pH + pOH =

14!!

VISUAL REPRESENTATION OF ION CONCENTRATION

PH VALUES OF COMMON SUBSTANCES

INDICATORS & METERS

• Certain dyes, known as indicators, turn different colors in solutions of different pH.

• An indicator a compound that can reversibly change color depending on the pH of the solution or other chemical change.

• Thymol blue is an example of an indicator.

• It is yellow in solutions whose pH is between 3 and 8 but blue in solutions whose pH is 10 or higher.

• Universal indicator utilizes all colors of the rainbow, where red is acidic and violet basic

• Litmus paper turns acidic conditions red, and basic conditions blue.

• phenolphthalein is pink under basic conditions, and clear otherwise (used in titrations).

• pH probes are also used to read concentration. The probe is inserted into the solution and using voltage, converts the value to a reading of pH.

SUMMARIZING UNDERSTANDING

A 4 x 6 index card has been provided to you. Please write the following: On the blank side, create a Venn Diagram listing everything you remember about acids and bases

from today’s discussion (properties, definitions), & classify a new* household item that is an acid or base.

On the lined side write down any clarifying question you have, or a topic you would like to know more about relating to acids & bases.

Example: ACID BASE

SOUR TASTE BITTER TASTEIONIZE IN WATER

LEARNER.ORG VIDEO QUESTIONS

What is a hydronium ion? Is it a proton donor or proton acceptor?

What is a hydroxide ion? Is it a proton donor or proton acceptor?

What is dissociation?

How can you make a neutral solution?

What is the definition of a strong acid? What is the definition of a weak acid? Name an example of each.

What is acid rain?

What does the pH scale represent?

Provide some examples of the roles acids and bases play in every day life