Bellringer

List an example of an acid or base you are familiar with in everyday life.

What do you know about the pH scale?

AgendaCollection Time

Book Project & Macromolecule notesCandy Molecules lab

Quick Experiment: Milk and Vinegar

Guided Notes: pH & the Effect on ProteinCompare Acids and BasesReview the use of pH scaleDescribe how changes in pH affect proteins

Properties of Acids

Sour taste

Corrosive to metals

Burns the Skin

Examples of Acids

Acetic Acid in Vinegar

Citric Acid in Oranges and Lemons

Hydrochloric Acid dissolves food in your stomach

Properties of BasesBitter Taste

Feel “Soapy”

Will irritate your skin

Examples of Bases

Milk of Magnesia

Bleach

Many Soaps

Acid/Base Chemistry

Acids release Hydrogen ions [H+] when mixed with water.

Bases absorb Hydrogen ions [H+] when mixed with water.

Neutralizations

Since Acids produce [H+] and Bases absorb [H+], it is possible for acids and bases to cancel one another.

When acids and bases cancel out it is called Neutralizing

pH Scale

The strength of Acids and Bases is measured using the pH scale

Scale goes from 0 to 14ACIDS = below 7NEUTRAL = exactly 7BASES = above 7

pH and Strength

The further an acid or base is from 7, the stronger it is.

ExamplesLemon Juice (2.0) is a stronger acid than

Beer (4.0) because a pH of 2 is farther from 7.

Ammonia (11.0) is a stronger base than Baking Soda (8.3) because a pH of 11 is farther from 7.

BrainPOP: Acid/Base

Protein Folding

Proteins are long chains of amino acids.

These chains bend and fold into a certain shape that allows them to perform their job.

The shape of the protein is held together by bonds between amino acids on different parts of the chain.

Protein Structure Video Clip

How Acids Denature Proteins

Acids destroy proteins by “denaturing” them. This means that the protein gets unwrapped and the shape is destroyed.

Acids can unwind proteins because the H+ [Hydrogen ions] interfere with the bonds that hold the protein together.

For this reason, it is important for living things to maintain a consistent pH level in bodily fluid. For example, human blood must stay at a pH of 7.4

H+

H+

H+

H+

H+

Explain what caused the milk to curdle. . .

Assignments

12 Review Questions

Using pH to identify liquids

Students should complete their Quarterly Assessment if not finished yesterday.