Acids, Bases, and Solutions Understanding Solutions Concentration and Solubility Describing Acids and Bases Acids and Bases in Solution Digestion and pH

Acids, Bases, and Solutions

Understanding Solutions

Concentration and Solubility

Describing Acids and Bases

Acids and Bases in Solution

Digestion and pH

Table of Contents

Acids, Bases, and Solutions - Understanding Solutions

What Is a Solution?

A solution has the same properties throughout. It contains solute particles (molecules or ions) that are too small to see.


What Is a Solution?

Solutions can be made from any combinations of solids, liquids, and gases.


Colloids and Suspensions

Colloids and suspensions are mixtures that have properties different from those of solutions.


Particles in a Solution

When a solution forms, particles of the solute leave each other and become surrounded by particles of the solvent.


Salt Dissolving in Water Activity

Click the Active Art button to open a browser window and access Active Art about salt dissolving in water.

- Understanding Solutions


Effects of Solutes on Solvents

At 0ºC, pure water freezes, but water mixed with a solute does not. Solutes lower the freezing point of a solvent.

Solid (frozen) water Liquid water solution


Identifying Main IdeasAs you read the section “What is a Solution?”, write the main idea in a graphic. Then write three supporting details.

A solution is a well mixed mixture that contains a solventand at least one solute.

The solvent is the substance present in the largest amount.

A solute is a substance present in a smaller amount than the solvent.

A solution has the same properties throughout.

Main Idea

A solution contains particles that are too small to see.

Detail Detail Detail Detail



Universal Solvent

Click the Video button to watch a movie aboutuniversal solvent.



End of Section: Understanding

Solutions


Calculating a Concentration

To calculate the concentration of a solution, compare the amount of solute to the amount of solution and multiply by 100 percent.

For example, if a solution contains 10 grams of solute dissolved in 100 grams of solution, then its concentration can be reported as 10 percent.

- Concentration and Solubility


Calculating a Concentration

Practice Problem

A solution contains 12 grams of solute dissolved in 36 grams of solution. What is the concentration of the solution?

33%


Acids, Bases, and Solutions - Concentration and Solubility

Solubility

Solubility is a measure of how much solute can dissolve in a solvent at a given temperature.


Temperature and Solubility

The solubility of the compound potassium nitrate (KNO3) varies in water at different temperatures.




KNO3 is least soluble at 0ºC.

Reading Graphs:

At which temperature shown in the graph is KNO3 least soluble in water?




Approximately 65 g of KNO3 are needed to saturate a water solution at 40ºC.

Reading Graphs:

Approximately what mass of KNO3 is needed to saturate a water solution at 40ºC?




KNO3 is about twice as soluble at 40ºC as it is at 20ºC.

Calculating:

About how much more soluble is KNO3 at 40ºC than at 20ºC?




No; the curve shows that solubility increases more with each 20ºC increase in temperature.

Interpreting Data:

Does solubility increase at the same rate with every 20ºC increase in temperature? Explain.



Building VocabularyAfter you read the section, carefully note the definition of each Key Term. Also note other details in the paragraph that contains the definition. Use all this information to write a meaningful sentence using the Key Term.


Key Terms: Examples:

dilute solution A dilute solution is a mixture that has only a little solute dissolved in a certain amount of solvent.

concentrated solution A concentrated solution is one that has a lot of solute dissolved in the same amount of solvent.

solubility Solubility is a measure of how much solute can dissolve in a solvent at a given temperature.

saturated solution A saturated solution contains so much solute that no more dissolves.

Key Terms: Examples:

unsaturated solution

supersaturated solution

An unsaturated solution can continue to dissolve more solute.

A supersaturated solution has more dissolved solute than is predicted by its solubility at the given temperature.


Links on Solubility

Click the SciLinks button for links on solubility.



End of Section: Concentration and Solubility

Acids, Bases, and Solutions - Describing Acids and Bases

Properties of Acids and Bases

Litmus is an example of an indicator, a compound that changes color when in contact with an acid or a base.

Acids, Bases, and Solutions - Describing Acids and Bases

Uses of Acids and Bases

Acids and bases have many uses around the home and in industry.


Question Answer

Asking QuestionsBefore you read, preview the red headings. In a graphic organizer like the one below, ask a what question for each heading. As you read, write answers to your questions.

What is an acid? An acid is a substance that tastes sour, reacts with metals and carbonates, and turns blue litmus paper red.

What is a base? A base is a substance that tastes bitter, feels slippery, and turns red litmus paper blue.

What are uses of acids and bases? Uses of acids include cleaning products, fertilizers, and car batteries; uses of bases include cleaning products, baking ingredients, and cement manufacturing.

- Describing Acids and Bases


Links on Acids and Bases

Click the SciLinks button for links on acids and bases.

- Describing Acids and Bases


End of Section:Describing Acids

and Bases

Acids, Bases, and Solutions - Acids and Bases in Solution

Acids and Bases in Solution

The table lists some commonly encountered acids and bases.


Strength of Acids and Bases

Strong acids and weak acids act differently in water. Hydrochloric acid is a strong acid. Acetic acid is a weak acid.


The pH Scale

A low pH tells you that the concentration of hydrogen ions is high. In contrast, a high pH tells you that the concentration of hydrogen ions is low.


Acid-Base Reactions

A reaction between an acid and a base is called neutralization. An acid-base mixture is not as acidic or basic as the individual starting solutions.


Acid-Base Reactions

Each salt listed in this table can be formed by the reaction between an acid and a base.


Previewing VisualsWhen you preview, you look ahead at the material to be read. Preview Figure 21. Then write two questions that you have about the diagram in a graphic organizer like the one below. As you read, answer your questions.

Neutralization

Q. What is a neutral solution?

A. A neutral solution is one that has a pH close to 7.

Q. What is neutralization?

A. Neutralization is a reaction between an acid and a base.

- Acids and Bases in Solution


More on the pH Scale

Click the PHSchool.com button for an activity about the pH scale.



pH

Click the Video button to watch a movie about pH.



End of Section: Acids and Bases

in Solution

Acids, Bases, and Solutions - Digestion and pH

What Is Digestion?

Chemical digestion breaks large molecules into smaller ones.

Acids, Bases, and Solutions - Digestion and pH

pH in the Digestive System

Foods are exposed to several changes in pH as they move through the digestive system.


SequencingSequence is the order in which a series of events occurs. As you read, make a flowchart that shows the sequence of changes in pH as food moves through the digestive system.

pH During Digestion

At a pH near 7, enzymes in the mouth start to break down carbohydrates.

At a pH near 2, stomach enzymes break down proteins.

At a pH near 8, enzymes in the small intestine complete the breakdown of carbohydrates, fats, and proteins.

- Digestion and pH


Links on Digestion and pH

Click the SciLinks button for links on digestion and pH.

- Digestion and pH


End of Section: Digestion and pH


Graphic Organizer

Solvents

Solutions

are made of

dissolve in

dissolve to form such as

conduct do not conduct

Solutes

Molecules Water

Electricity

Ions


End of Section: Graphic Organizer

Documents

Acids, Bases, and Solutions Understanding Solutions Concentration and Solubility Describing Acids and Bases Acids and Bases in Solution Digestion and pH