chapter 9 lesson 2 - weebly

Chapter 9 Lesson 2

Materials Needed Today

Please take these materials out of your backpack.

•Pencil

•HW: Elements 21-36 Cards DUE FRIDAY (no drawing)

Hot Sync Tuesday 2/11/14

Answer the following question in a complete sentences AND SHOW WORK on your hot sync. Copy

Graph

1) v

acid

hydronium ion

base

pH

indicator

pH meter

9.2 Acidic, Basic, and Neutral Solutions

Acids

• The pH scale measures the acidity of a solution.

• Acids are substances that release a positively charged hydrogen ion, H+, in water.


What is a hydronium ion?

• The H+ ion combines with water to form H3O+,

the positively charged hydronium ion.

• When an acid dissolves, it releases a hydrogen ion.


Hydrogen ion Water molecule Hydronium ion

Uses of Acids

• Acids are important in several body processes, including breaking down food in the stomach.

• Acids are also used in making many products, such as fertilizers, detergent, and cleaners.


Bases

• Bases are substances that produce negatively charged hydroxide ions when dissolved in water.

• Most bases are ionic compounds


What is a hydroxide ion?

• In water, bases separate into a positive ion and the hydroxide ion (OH–).

• All the properties of bases are a result of the presence of hydroxide ions that form when the base is dissolved in water.


Uses of Bases

• Common bases include baking soda and cleaning agents.

• Bases are also used to produce new products, such as soap, paper, and plaster.


Acids and Bases

http://glencoe.mcgraw-hill.com/sites/0078741858/student_view0/brainpop_movies.html






What is pH?

• pH is a numerical scale used to indicate how acidic or basic a solution is.

• The pH scale runs from 0 to 14.

– Acids are below 7; strong acids are near 0.

– Bases are above 7; strong bases near 14.

– Neutral solutions have a pH of 7.


pH and Hydronium Ion Concentration

• pH is the measure of the concentration of hydronium ions, H3O

+, in solution.

• When the H3O+ concentration increases,

pH decreases.


Hydroge

n ion

Water

molecule

Hydroni

um ion

Hydronium Ions, Hydroxide Ions, and pH

• All acid and base solutions contain both hydronium and hydroxide ions.


Hydronium Ions, Hydroxide Ions, and pH (cont.)

• Acids have a greater hydronium ion concentration.

• Bases have a greater hydroxide ion concentration.


Comparing pH Values

• Each unit on the pH scale represents a 10-fold increase.

• An acid with a pH of 1 contains 10 times as many H3O

+ ions as an acid with a pH of 2.


Neutralization pH Values

• Acids and bases react together to neutralize each other.

• Stomach acid reacts with magnesium hydroxide in the following equation:

2HCl + Mg(OH)2 → MgCl2 + 2H2O

• Neither the products is acidic or basic.


How is pH measured?

• Indicators are compounds that change color within a particular pH range.

• Indicators can be used to determine approximate pH.


pH Strips

• Litmus is one of the simplest indicator test papers but also the least accurate.

• pH testing strips are a quick way of determining the approximate pH of a solution.


pH Meters

• pH meters are electronic instruments with an electrode that is sensitive to hydronium ions present in a solution.

– Accurately measures pH

– Requires an electric source to operate


Acid Reactions

Lesson 2 Review

An acid with a pH of 3 is contains how many times as many hydronium ions as an acid with a pH of 6?

A 1000

B 3

C 30

D 100


A B C D

0% 0%0%0%

1. A

2. B

3. C

4. D

Lesson 2 Review

When an acid and base are mixed, the products are ____ and ____.

A water; a base

B water; ammonia

C water; salt

D ammonia; salt


A B C D

0% 0%0%0%

1. A

2. B

3. C

4. D

Lesson 2 Review

Red litmus paper is dipped in a solution. The paper turns blue. The solution must have been ____.

A acidic

B homogeneous

C basic

D polar


A B C D

0% 0%0%0%

1. A

2. B

3. C

4. D

Materials Needed Today Please take these materials out of your backpack.

•Pencil

•HW: Finish Poster

•Elements 21-36 Cards DUE FRIDAY (no drawing)

Hot Sync Wednesday 2/12/14

Answer the following question in a

complete sentences on your hot sync.

Copy table


•Pencil

•Acid rain poster rubric

•HW: Finish Lab Write up

•Elements 21-36 Cards DUE FRIDAY (no drawing)

•

Hot Sync Thursday 2/13/14

Answer the following question in a

complete sentences SHOW WORK

on your hot sync. Copy Graph.


•Pencil

•Acids and bases Lab

•Elements 21-36 Cards

Hot Sync Friday 2/14/14

Answer the following essential

questions in 2 paragraphs (5 sentences

each).

Paragraph 1:

How does acid

affect me?

Paragraph 2:

What can I do with

more knowledge of

acids and bases?

chapter 9 lesson 2 - weebly

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