7.4 Acids and Bases in Solutions 5E Mr. Sapalicio Monterey Highlands Elementary Chemistry and Physical Science

? Does all lemonade taste the same? No, some can be sweet, sour, strong or weak. What can you do to make it more sour? Add more lemon juice. This is an example of an acid in water.

Acids in Solutions Most acids while in a water solution produce hydrogen ions and a negative ion. Hydrogen ions (H+)- an atom of hydrogen that has lost its electron. Hydrogen ions are the key to the reactions of acids. *An acid produces hydrogen ions (H+) in water. Ex: HCl H+ + Cl-

Acids in Solutions Hydrogen ions react with blue litmus paper, turning it red. Litmus paper materials- wood cellulose, lichens, and adjunct compounds. Copy 3 forumlas for acids and bases from chart on page 275.

Hydrogen Ions (H+) Acid ???????????????????????????????????????????? What explains the properties of acids? Hydrogen Ions (H+) Acid

Bases in Solutions NaOH Na+ + OH- Hydroxide Ion (OH-) a negative ion made of oxygen and hydrogen. When bases dissolve in water, the positive ions and hydroxide ions separate. NaOH Na+ + OH-

Bases in solutions NH3 + H2O  NH4+ + OH- CaO + H2O  Ca + OH- Not all bases contain hydroxide ions (OH-) Ammonia (NH3), a base reacts with water to form hydroxide ions. NH3 + H2O  NH4+ + OH- CaO + H2O  Ca + OH- A base produces hydroxide ions (OH-) in water.

Hydroxide Ions (OH-) ???????????????????????????????????????????? Base What explains the bitter taste, slippery feeling, and red litmus paper blue? Hydroxide Ions (OH-) Base

Strength of Acids and Bases The word strength refers to how well an acid or base produces ions (+, -) in water. Look at figure 19 on page 276, draw this on your right side. In a strong acid (hydrochloric, sulfuric, nitric) the solution forms many more ions (H+). (green and blue spheres). In the weaker acid (acetic, citric) not as many ions are formed.

Strength of Acids and Bases The word strength refers to how well an acid or base produces ions (+, -) in water. In a strong base the solution also forms many more ions (OH-) In the weaker base (baking soda) not as many ions are formed.

Measuring the pH What is pH- Potential for hydrogen pH scale- a range of values from 0-14. It is used to express the concentration of hydrogen ions in a solution. So what element is the pH scale looking for? Hydrogen , H+, it is looking for acids.

How to read the pH scale p. 277 If an item ranges from; 8-14- a base 7- Neutral- it is neither acid, nor base 0-6 it means it is acidic

Base + Acid= Neutralization Mixing them Neutralization- a reaction between an acid and a base. The level of the pH of something after the mixture would depend on the strength of the acid and the base. Ex: a lot of strong base mixed with only a bit of strong acid= base Base + Acid= Neutralization