ACID BASE CHEMISTRY TECH 51 SYRACUSE 14 REVIEW

ACID BASE CHEMISTRY TECH 51 – SYRACUSE 14

REVIEW The following slides are intended to serve as an overview of your text, not a replacement. You are responsible for all material in the chapter. Some of the information has been simplified as the course is an OVERVIEW and not intended to be a high school chemistry class.

DEFINITIONS If you read most science texts about acids and bases you will read that acids always produce hydrogen ions (H+) and bases produce hydroxide ions (OH-). But this can get you into trouble as it does not account for a lot of chemicals that have properties of acids and bases where the ions mentioned may not be present.

Acids An acid is defined as any substance that gives away or liberates a hydrogen ion. Remember that a hydrogen ion is a proton. FOR THIS REASON, AN ACID IS REFERRED TO AS ANY SUBSTANCE THAT IS A PROTON DONOR.

Hydrogen Ion So an acid liberates a hydrogen ion. Since a hydrogen ATOM is composed of ONE proton and ONE electron, then the ion must be different. Hydrogen DOES NOT want to lose the electron, but it is a very small atom and it loses most “tug of wars” with larger atoms. This results in a single proton with no electron. The proton goes crazy and seeks out electrons. This is where water comes into play.

Hydronium Ion • A hydronium ion is formed when the proton from the Hydrogen Ion combines with a molecule of water. If you remember, water is covalently bonded and the atoms share electrons unevenly. This means that the proton, with a positive charge, will combine to the negatively charged part of the water molecule. -SEE NEXT SLIDE-

HYDRONIUM ION WHEN THE WATER ACTS AS A BASE AND ACCEPTS THE PROTON THE ION THAT FORMS IS CALLED A HYDRONIUM ION. NOTICE THAT IT IS ACTUALLY A POLYATOMIC MOLECULE WITH A CHARGE OF +1. See the next slide for a different example.

Here you see two different pictures showing the same thing. For a hydronium ion to form, the hydrogen ion combines with the water to form the hydronium ion. Technically, the acid is the H 3 O+ but we will write it as H+.

HERE YOU CAN SEE THAT WHEN HCl IS ADDED TO WATER, THE WATER ACTUALLY ACTS LIKE A BASE. HOW? SINCE THE HCl GIVES A PROTON, IT IS AN ACID (BY DEFINITION see previous slide 4). SINCE THE WATER IS ACCEPTING THE PROTON IT BECOMES A BASE (AGAIN, BY DEFINITION, see slide 5).

BASES Bases receive protons, so by this definition, a base is defined as any substance that receives a hydrogen ion. BASES ARE PROTON ACCEPTORS. (or proton receiver) Years ago, bases were defined as anything that liberated (gave off) a OH- ion, but this definition did not account for many things that had properties of a base but no OH.

HYDROXIDE IONS Hydroxide ions can be formed when substances are added to water, such as ammonia, or liberated when compounds dissociate in water releasing hydroxide ions. For example, when the substance Na. OH is added to water, it separates forming Na+ and OH-.

Ammonia When ammonia (NH 3) is added to water it acts as a base as it is a proton acceptor. This results in the formation of a OH- ion. NOTICE THAT THIS MEANS THAT WATER IS NOW AN ACID. EARLIER IT WAS A BASE.

AMPHOTERIC This is the term that is given to a substance that has about the same ability to behave as an acid as it does a base. Since water behaves in this way, it is a good example of a substance that is amphoteric.

PROPERITES ACIDS-proton donor • Taste sour • p. H less than 7 • Turn litmus red • Neutralize base • + metal H 2 • Conduct electricity • Turn congo red blue BASES-proton acceptor • Taste bitter • p. H greater than 7 • Turn litmus blue • Neutralize acid • Feel slippery • Conduct electricity • Turn PHTH pink

SALT When you are sitting at the dinner table and your parents ask you to “pass the salt” they are asking specifically for Na. Cl. It is a salt though, because it is a metal, Na+, and a nonmetal, Cl. By definition though, A SALT IS ANY IONIC COMPOUND FORMED WHEN A METAL AND ANY NONMETAL COMBINE, except H and OH (this forms water, covalently bonded)

STRENGTH What makes a substance have the characteristics of an acid or base is the ability to form ions. When an acid or base forms ions then the characteristics of an acid or base form. If ions form easily, then a substance is said to be STRONG. If a chemical does not form ions easily, then it is said to be WEAK. This goes against what you might think as a strong bond will hold onto an atom more tightly than a weaker bond.

CONCENTRATION It is the ION that forms that causes the characteristics of the acid or base, not the actual acid or base. So, keeping this in mind, it is the number of these ions that affect the properties of the solution that the acid or base is dissolved in. One method to determine how concentrated a solution is would be to check the ability to conduct electricity.

IONS AND ELECTRICITY Ions must be present for electricity to flow. Pure water has no ions and therefore will not conduct electricity. If an acid or base is dissolved in pure water, the degree to which it is dissolved can be determined by how much electricity is conducted. The more a substance dissolves AND DISSOCIATES (forms ions), the more electricity is conducted. These substances are called ELECTROLYTES.

p. H refers to “power of Hydrogen”. It is a mathematical calculation of the negative logarithm of the hydronium ion concentration: p. H = -log[H 3 O] Since this is an overview course, we will never calculate p. H.

p. H Scale p. H is a scale used to measure the concentration of the hydronium ion. A p. H of 7 is NEUTRAL. A p. H less than 7 is ACIDIC. Greater than 7 is BASIC. Since it is logarithmic, you need to remember that a p. H of 5 is 10 TIMES GREATER THAN A p. H of 6.

INDICATORS Indicators are chemicals that are used to test for the presence of other chemicals by color changes. With acid base chemistry most people think of LITMUS. In Acid, LITMUS turns RED. In Base, LITMUS turns BLUE.

PHTH and Congo Red We will use two other indicators in lab, PHENOLTHTHALEIN (PHTH) and Congo Red. PHTH will be used to test for Base. In the presence of OH Base, PHTH will turn a pink color The more intense the PINK, the more OH is present. Congo Red tests for Acid. In the presence of an acid, it will turn dark blue.

Indicators vs. p. H Meters Indicators will not be as accurate as p. H meters since the Hydronium or Hydroxide ion must be present for the indicator to react. Therefore, when you see a color change, you know that the p. H of the solution is NOT a p. H of 7 but actually a bit above or below depending on the indicator used.

ACIDIC RAIN vs. ACID RAIN There is a difference between acidic rain and acid rain. All rain is acidic. This is because there is carbon dioxide in the atmosphere. This carbon dioxide combines with water to form CARBONIC ACID. CO 2 + H 2 O H 2 CO 3 Carbonic acid formation is why soft drink companies add carbon dioxide to soda. It actually flavors the drink. A flat soda will taste sweeter.

Carbonic Acid CO 2 + H 2 O H 2 CO 3 Carbonic acid is not a very strong acid and easily breaks down into carbon dioxide and water. It is the reason that carbon dioxide is added to sodas. When the carbon dioxide forms carbonic acid, it gives a slight acidic flavoring to the drink. This is why a “flat” soda will taste different than a carbonated beverage.

Testing for CO 2 The fact that carbon dioxide combines with water to form carbonic acid should bring back memories. Remember testing for carbon dioxide with phenol red? Remember how it took a short time for the color to change? Phenol red actually tests for ACID. So what does that mean?

Carbonic acid will cause rain water to have a natural p. H between 5 – 7. When other factors react to lower the p. H of rain below a p. H of 5, such as nitrates and sulfates, then rain is considered to be ACID RAIN. When rain water is acidic is has dire effects on the ecosystem as well as leaching toxic metals from the soil. This indirectly affects you as some of the metals include Al, which has dire effects on the body.

Carbonic Acid Blood Carbonic acid also builds up in your blood as well. When this happens you automatically have built in buffering systems to keep the p. H of your blood at a constant p. H level of about 7. 3 – 7. 4. (Your body makes bicarbonates). This is also the reason that you cannot hold your breath indefinitely. You have to exhale the Carbon Dioxide.

Where does the CO 2 go? Atmospheric CO 2 is increasing, but not at the rate that is consistent with its production. So where is it going? The answer is the ocean. The ocean is acting as a giant “sink” that is absorbing excess CO 2. The problem is that we are producing it faster than the ocean can absorb it.

NITRATES AND SULFATES Nitrates and Sulfates, like carbon dioxide, react with water in the atmosphere to form NITRIC ACID and SULFURIC ACID. These acids, in conjunction with the carbonic acid, cause the p. H of rain to drop well below a p. H of 5. When this happens a domino effect of negative consequences begin to occur to the ecosystem.

Antacids vs. Base Antacids are typically bases that neutralize acids inside your stomach. Typically, the stomach p. H is between 2 or 3. When it drops below this, people may experience acid indigestion. Antacids do not necessarily raise stomach p. H to 7, they just increase it from below 2 to between 2 or 3. You do not want a p. H of 7 in your stomach.

Effects of Metals There are four primary metals that accompany base ions with antacid products. Each metal has specific affects on the body. These metals are as follows Na-sodium Ca-calcium Mg-magnesium Al-aluminum

Sodium-Na Sodium is an essential element for the proper functioning of the body. It helps to maintain proper fluid levels, assist in nerve impulses, and helps muscles contract and relax. Your kidneys regulate your sodium levels. People who have difficulty regulating sodium will begin to retain more fluids. This elevates blood pressure as well as increases blood volume, making the heart work harder.

HIGH SODIUM FOODS/ Can the Cans Canned and pre-packed foods tend to be higher in sodium than their fresh counterparts. This is especially true of soups, frozen dinners and other convenience foods, as well as dehydrated powders for making sauces and salad dressings. Other foods high in sodium include: Soy sauce Catsup Worcestershire sauce Chili sauce Mustard Pickles and relishes Olives Processed cheese and cheese spread Baking powder, baking soda and most baked goods, which contain these ingredients Canned or frozen vegetables in sauce Monosodium glutamate (MSG) Frankfurters, cured ham, sausages and luncheon meats Salted nuts, chips and other snack foods Any food additive with the word "sodium" (sodium benzoate, a preservative; sodium phosphate, an emulsifier and stabilizer)

Ca-Calcium is one of the most essential elements in the body as it is used in bones, teeth, soft tissues, and many metabolic processes. It regulates permeability of cells as well as clotting of blood, muscle contractions, and nerve functions. Calcium helps to regulate blood pressure.

Foods rich in Calcium Food with Calcium Dairy products Milk† Swiss cheese Yogurt American cheese Serving size 1 cup 1 oz (slice) Ice cream or frozen dessert 1/2 cup Cottage cheese Parmesan cheese Powdered nonfat milk 1/2 cup 1 Tbs 1 tsp Calcium per serving (mg)* 290 -300 250 -270 240 -400 165 -200 90 -100 80 -100 70 50 Sardines in oil (with bones) 3 oz 370 Canned salmon (with bones) 3 oz 170 -210 Broccoli Soybean curd (tofu) Turnip greens Kale Corn bread Egg 1 cup 4 oz 1/2 cup, cooked 2 1/2 -in. square 1 medium 160 -180 145 -155 100 -125 90 -100 80 -90 55

Mg-Magnesium is the second most common mineral in the body, behind calcium. Most is found in the bones and muscles (86%) while the rest is found in the brain, heart, liver, kidney, and blood. Mg is used in over 300 enzyme reactions of the body. It is used to synthesize nucleic acids, proteins, relax muscles, prevent kidney stones, and helps prevent diabetes. Mg is also used to help regulate blood pressure.

Whole food sources of Magnesium Whole Food Sources Brown rice, cooked Serving Magnesium (mg) 1 cup 83. 8 Almonds, raw 1 ounce 81. 1 Spinach, cooked 1/2 cup 78. 3 Swiss chard, cooked 1/2 cup 75. 2 Lima beans, cooked 1/2 cup 62. 9 Avocado Peanuts*, raw Hazelnuts, raw Okra, cooked 1 large 1 ounce 1/2 cup 50. 0 49. 8 49. 0 45. 6 Black-eyed peas, cooked 1/2 cup 42. 8

Aluminum has no role in the human body. As of this time, there are no known organisms that use aluminum in any of their biological processes. It is toxic to all living creatures. Aluminum has been linked to the following: Alzheimer’s, Parkinson’s, liver disease, cancers, heart problems, bone disorders, infection, memory loss, speech disorders, kidney disorders, and the list goes on. It is estimated that the average person takes in approximately between 3 and 10 mg of Al per day.

Sources of Al Al can be absorbed into the body through the digestive tract, the lungs and the skin, and is also absorbed by and accumulates in the bodies tissues. Aluminum is found naturally in our air, water and soil. It is also used in the process of making cooking pots and pans, utensils and foil. Other items such as over the counter pain killers, antiinflammatory products, can also contain aluminum. Aluminum is also an additive in most baking powders, is used in food processing, and is present in antiperspirants, toothpaste, dental amalgams, bleached flour, and grated cheese. One of the biggest source of aluminum, however, comes from our municipal water supplies.

Products containing Al • THE FOLLOWING PRODUCTS MAY CONTAIN ALUMINUM-Check the label: Foods made with aluminized baking powder*, self-rising flour*, and salt. The following are some of these products: Microwave popcorn Salted snacks Hot cocoa mixes Coffee creamers Pickles and relish *Flour tortillas *Pizza crust *Muffins *Doughnuts *Cookies *Pancakes *Waffles *Cupcakes *Cakes *Baking mixes *Brownies *Pastries *Corn bread *Banana bread *Carrot bread *Dipping batter for fried foods

Products containing Al • Antiperspirents Many body lotions and creams Most cosmetics Shampoos and conditioners Soaps Suntan lotions Lip Balm Etc.