Lesson 3 Describing Acids and Bases Description By

Lesson 3 Describing Acids and Bases Description By the end of this lesson, the student should be able to: 1. Describe the properties of acids. 2. Describe the properties of bases. DCI-MS-PS 1. B. 1 Substances react chemically in characteristic ways. In a chemical process, the atoms that make up the original substances are regrouped into different molecules, and these new substances have different properties from those of the reactants.

Bog Bodies Even in Shakespeare’s time it was known that tanning, the process of making leather, helps preserve body tissues. Hundreds of years later, the body of a 2, 300 -year-old man was found in the peat bogs of Europe. The man is a bog body, like the one shown in the photo. Bog bodies are the remains of human bodies that have been preserved in the highly acidic conditions of peat bogs. � The bog acids are similar in strength to vinegar. They naturally pickle the human bodies. The lack of oxygen and cold temperatures of Northern Europe cause the acids to saturate body tissues before they decay. As a result, the organs, hair, and skin are all preserved. The acids dissolve the bones of the bog bodies, but details like tattoos and fingerprints can still be seen on some of the bodies. �

� What Are the Properties of Acids? Acids are compounds with specific properties. An acid reacts with metals and carbonates, tastes sour, and turns blue litmus paper red. Lemons, oranges, tomatoes, and vinegar all contain acids. Hydrochloric acid in your stomach helps with digestion, and sulfuric acid drives many types of batteries. � Acids react with certain metals to produce hydrogen gas. When these metals, including copper, zinc, and iron, react, the metals seem to disappear in the solution. This is one reason acids are described as corrosive, meaning they “wear away” other materials. Acids also react with carbonate ions. One product of the reaction of an acid with a carbonate is the gas carbon dioxide. Geologists use this property of acids to identify rocks such as limestone that include carbonate ions. � Although sour taste is a characteristic of many acids, it is not one you should use to identify a compound as an acid. It is never safe to taste unknown chemicals. Chemists use indicators to test for acids. Litmus paper is an example of an indicator, a compound that changes color when it comes in contact with an acid or a base. Acids turn blue litmus paper red.

What Are the Properties of Bases? Bases are compounds that, like acids, have specific properties. The properties of bases are sometimes described as being the “opposite” of those of acids. � A base tastes bitter, feels slippery, and turns red litmus paper blue. Ammonia, baking soda, and many soaps and detergents are bases. � Bases have a slippery feel. The slippery feel of your shampoo is a property of the bases it contains. Just as you avoid tasting an unknown substance, you wouldn’t want to touch one, either. Strong bases can irritate your skin. A safer way to identify bases is by their other properties. Unlike acids, bases do not react with metals or with carbonates, but they do react with acids in a chemical reaction called neutralization. Bases turn red litmus paper blue. �

Describing Acids and Bases Acid and Base Properties Which items are acid and which are base? Window cleaner Vinegar Limes Dish soap

Describing Acids and Bases Properties of Acids and Bases What are the properties of acids and bases?

Lesson 4 Acids and Bases in Solution � Description � By the end of this lesson, the student should be able to: 1. Identify the types of ions acids and bases form in water. 2. Describe what happens in a neutralization reaction. � DCI-MS-ETS 1. B. 2 � There are systematic processes for evaluating solutions with respect to how well they meet the criteria and constraints of a problem.

Ocean Stingers Planet Diary You’ve probably heard of venomous animals like rattlesnakes and black widow spiders. Did you know that some of the most venomous creatures in the world are jellyfish? Some jellyfish stings can permanently scar and even kill their victims. Jellyfish use their venom to stun and paralyze both prey and predators, including humans. A jellyfish sting can quickly turn a day at the beach into a dash to the hospital. Luckily, most jellyfish stings can be easily treated. � The venom of some jellyfish contains bases. Bases can be neutralized, or deactivated, by an acid. The best way to treat some jellyfish stings is to rinse the affected area with vinegar. Vinegar is a solution containing acetic acid, which is a weak acid that is safe for your skin. �

What Ions Do Acids and Bases Form in Water? In a solution with water, most acids separate into hydrogen ions and negative ions. A hydrogen ion (H⁺) is an atom of hydrogen that has lost its electron. The production of hydrogen ions helps define an acid. An acid produces hydrogen ions (H⁺) in water. The hydrogen ions are responsible for corroding metals and turning blue litmus paper red. � Acids may be strong or weak. Strength depends on how well the acid dissociates, or separates into ions, in water. A strong acid dissociates to a high degree; a weak acid, less so. � Bases also dissociate in solution. A base produces hydroxide ions (OH-) in water. The hydroxide ion (OH-) is a negative ion made up of oxygen and hydrogen. Hydroxide ions are responsible for the bitter taste and slippery feel of bases, and for turning red litmus paper blue. Strong bases readily produce hydroxide ions in water; weak bases do not. � To determine the strength of an acid or base, the p. H scale is used. The p. H scale ranges from 0 to 14 and expresses the concentration of hydrogen ions in a solution. The most acidic substances are found at the low end of the scale; the most basic substances at the high end. A p. H of 7 is neutral. �

What Are the Products of Neutralization? � When an acid and a base are mixed, the reaction produces a salt and water. The reaction between an acid and a base is called neutralization because the resulting mixture is not as acidic or basic as the individual starting solutions were. The final p. H depends on the volumes, concentrations, and strengths of the reacting acid and base. The salt that forms from a neutralization reaction is any ionic compound made from the positive ion of a base and the negative ion of an acid. In a neutralization reaction, an acid reacts with a base to produce a salt and water.

The p. H Scale Interactive Art � Have you had any fruit to eat recently? If so, an acid was probably part of your meal. Acids are important parts of our lives. Folic acid, key to cell growth, is found in green, leafy vegetables like spinach and kale, as well as most grains. Hydrochloric acid in your stomach helps with digestion. Phosphoric acid is used to make plant fertilizers. Sulfuric acid drives many kinds of batteries. Acids have specific characteristic properties. They react with metals and carbonates, taste sour, and turn blue litmus paper red.

� Bases are another group of compounds that can be identified by their common properties. A base tastes bitter, feels slippery, and turns red litmus paper blue. The properties of bases are often described as the "opposite" of acids, and are sometimes referred to as "alkaline. " Bases have many uses. Ammonia is used in fertilizers and household cleaners. Many soaps and detergents contain bases, which create a slippery feel. Baking soda is a base called sodium bicarbonate, which causes baked goods to rise. Other foods containing bases include almonds and cocoa beans.

� Chemists use a scale called p. H to classify a substance as an acid or base. The p. H scale ranges from 1 to 14. The most acidic substances are at the scale's low end. We call these strong acids. The most basic materials, the strong bases, are at the high end. A p. H of 7 is neutral, meaning that it is neither an acid nor a base. Substances that fall toward the center of the scale are considered weak acids or weak bases. Low p. H means the concentration of hydrogen ions in a substance is high, and the concentration of hydroxide ions is low. High p. H means the opposite is true. Each unit of the scale represents a tenfold (10 x) change in the H ion concentration. p. H level can affect how some foods are made. Yogurt is created when milk ferments, creating acid that thickens and sours the milk.

�Antacid has a p. H of 11. What does that tell you about its concentration of hydrogen ions? What does that tell you about its concentration of hydroxide ions? �A lemon has a p. H of 2. Would it have a higher or lower concentration of hydrogen ions than a banana with a p. H of 4. 8? Explain.

Acids and Bases in Solution Common Acids The table lists some common acids.

Acids and Bases in Solution Strength of Acids In solution, strong acids act differently than weak acids do. How would ions of acetic acid act in solution?

Acids and Bases in Solution Common Bases Many of the bases shown are made of positive ions combined with hydroxide ions.

Acids and Bases in Solution Hydrochloric acid p. H = ______ Lemon p. H = ______ The p. H Scale The p. H scale helps classify solutions as acidic or basic. What is the p. H of the substances in the boxes? Vinegar p. H = ______ Banana p. H = ______ Pure water p. H = ______ Blood p. H = ______ Baking soda p. H = ______ Antacid p. H = ______ Drain cleaner p. H = ______

Acids and Bases in Solution Predict the p. H Where on the p. H scale does each item belong? Soap Tomato Ammonia

Acids and Bases in Solution Neutralization What would be the appropriate color to indicate the p. H levels?

Acids and Bases in Solution Common Salts The table lists common salts produced from neutralization reactions. Complete the table with the formula for each salt.