Section 2–2Section 2–2

ObjectiveObjective

This section describes the makeup of This section describes the makeup of water molecules. It also explains water molecules. It also explains whatwhatacidic solutions and basic solutions acidic solutions and basic solutions are.are.

The Water Molecule The Water Molecule

Is the following sentence true or Is the following sentence true or false? false?

A water molecule is neutral.A water molecule is neutral.

TRUETRUE

2. 2. What results from the What results from the oxygen atom being at one end oxygen atom being at one end

of a water molecule and theof a water molecule and thehydrogen atoms being at the hydrogen atoms being at the

other end?other end? The oxygen end of the molecule has The oxygen end of the molecule has

a slight negative charge and the a slight negative charge and the hydrogen end has a slight positive hydrogen end has a slight positive charge.charge.

3. 3. Why is a water molecule Why is a water molecule polar? polar?

There is an uneven distribution of There is an uneven distribution of electrons between the oxygen and electrons between the oxygen and hydrogen atoms.hydrogen atoms.

4. 4. Circle the letter of each Circle the letter of each sentence that is true about sentence that is true about

hydrogen bonds.hydrogen bonds.a.a. A hydrogen bond is stronger than an ionic A hydrogen bond is stronger than an ionic

bond.bond.b. b. The attraction between the hydrogen The attraction between the hydrogen

atom on one wateratom on one watermolecule and the oxygen atom on another molecule and the oxygen atom on another water molecule is an example.water molecule is an example.

c.c. A hydrogen bond is stronger than a A hydrogen bond is stronger than a covalent bond.covalent bond.

d. d. They are the strongest bonds that form They are the strongest bonds that form between molecules.between molecules.

Form of AttractionForm of Attraction

FORMS OF ATTRACTIONFORMS OF ATTRACTION

DefinitionDefinition

Attraction between Attraction between molecules of the same substancemolecules of the same substance

Attraction between Attraction between molecules of different substancesmolecules of different substances

6. 6. Why is water extremely Why is water extremely cohesive?cohesive?

It is very cohesive because of It is very cohesive because of hydrogen bonding.hydrogen bonding.

7. The rise of water in a narrow 7. The rise of water in a narrow tube against the force of tube against the force of

gravity is called.gravity is called.

8. 8. How does capillary action How does capillary action affect plants?affect plants?

a.a. Capillary action is one of the Capillary action is one of the forces that draws water out of forces that draws water out of the roots of a plant and up into the roots of a plant and up into its stems and leaves. its stems and leaves.

9. 9. What is a mixture?What is a mixture?

a.a. A mixture is a material composed of A mixture is a material composed of two or more elements or compounds two or more elements or compounds that are physically mixed together that are physically mixed together but not chemically combined.but not chemically combined.

10. 10. A mixture of two or more A mixture of two or more substances in which the substances in which the

molecules of the substances molecules of the substances areare

evenly mixed is called a(an) .evenly mixed is called a(an) .

11. 11. The greatest solvent in the The greatest solvent in the world world

12. 12. What is a suspension?What is a suspension?

a.a. A suspension is a mixture of water A suspension is a mixture of water and non-dissolved substances that and non-dissolved substances that are so small they do not settle out.are so small they do not settle out.

SUBSTANCES IN SOLUTIONSSUBSTANCES IN SOLUTIONS

Chemistry of LifeChemistry of Life

Acids, Bases, and pHAcids, Bases, and pH

Two water molecules can Two water molecules can react to form .react to form .

Why is water neutral despite Why is water neutral despite the production of hydrogen the production of hydrogen ions and hydroxide ions?ions and hydroxide ions?

It is neutral because the number of It is neutral because the number of positive hydrogen ions produced is positive hydrogen ions produced is equal to the number of negative equal to the number of negative hydroxide ions produced.hydroxide ions produced.

What does the pH scale What does the pH scale indicate? indicate?

a.a. It indicates the concentration of H+ It indicates the concentration of H+ ions in solution.ions in solution.

Which direction is increasingly Which direction is increasingly acidic and which is acidic and which is increasingly basic.increasingly basic.

How many more H+ ions does How many more H+ ions does a solution with a pH of 4 have a solution with a pH of 4 have

than a solution with athan a solution with apH of 5pH of 5

Circle the letter of each Circle the letter of each sentence that is true about sentence that is true about

acids.acids.a.a. Acidic solutions have pH values below Acidic solutions have pH values below

7.7.b. b. An acid is any compound that forms An acid is any compound that forms H+ ions in solution.H+ ions in solution.c. c. Strong acids have pH values ranging Strong acids have pH values ranging from 11 to 14.from 11 to 14.d. d. Acidic solutions contain higher Acidic solutions contain higher concentrations of H+ ions thanconcentrations of H+ ions thanpure water.pure water.

20. 20. Circle the letter of each Circle the letter of each sentence that is true about sentence that is true about

bases.bases.a.a. Alkaline solutions have pH values below 7.Alkaline solutions have pH values below 7.

b.b. A base is a compound that produces OH– A base is a compound that produces OH– ions in solution.ions in solution.

c.c. Strong bases have pH values ranging Strong bases have pH values ranging from 11 to 14.from 11 to 14.

d.d. Basic solutions contain lower Basic solutions contain lower concentrations of H+ ions thanconcentrations of H+ ions thanpure water.pure water.

21. 21. What are buffers?What are buffers?

a.a. Buffers are weak acids or bases that Buffers are weak acids or bases that can react with strong acids or bases can react with strong acids or bases to prevent sharp, sudden changes in to prevent sharp, sudden changes in pH.pH.10 times10 times