How does he do this magic trick?
https://www.youtube.com/watch?v=ujkuW-0cpNw&t=32s Acids and Bases Two special classes of compounds Elements •Contain a single kind of atom Compounds •Substances that are chemically formed •They have physical and chemical properties that are different from the elements that make them up. •They are formed as the result of a chemical reaction. Hydrogen (an explosive gas) and oxygen (an explosive gas) combine to form the compound water (a harmless liquid).
Here, the hydrogen gas in the zeppelin SS Hindenburg reacts with oxygen in the air to make water. Source: Photo courtesy of the US Navy, http://commons.wikimedia.org/wiki/File:Hindenburg_burning.jpg. Acids and Bases •Acids and bases are special classes of compounds that exhibit common chemical properties. Acids and Bases •Acids and Bases can be helpful or harmful. •Acids and bases can be weak or strong. •YOU MUST ALWAYS BE CAREFUL WHEN WORKING WITH ANY CHEMICALS! Characteristics of Acids
•Have a sour taste (never taste an unknown!) •They have Hydrogen atoms which have given up their electron, making them positive ions. (H+) Characteristics of Acids
• They turn blue litmus paper red
•They react with metals to release Hydrogen gas.
http://www.youtube.com/watch?v=PqUOGc6P05c What is an ion?
An ion is an atom that has lost or gained an electron giving it a positive (+) or negative (-) charge. USES OF ACIDS •Citric acid and ascorbic acid (Vitamin C) are found in orange juice •Carbonic acid and phosphoric acid give a “bite” to soft drinks •Acids in your stomach aid in digestion •Sulfuric acid is the most widely used industrial acid in the world. It is used in making metals, paper, paints, and fertilizers. Sulfuric Acid on a Sponge Characteristics of Bases
•Have a bitter taste (never taste an unknown!) •They feel slippery Characteristics of Bases They have Hydroxide (OH) compounds which have taken on an electron, making them negative ions. (OH-) Characteristics of Bases
• They turn red litmus paper blue •They do not react with metals. Uses of Bases •Bases are used in soaps (remember, bases are slippery) •Bases are used to make paper, in oven cleaners, and to unclog drains •Ammonia is a base and is used in many household cleaners
Detecting Acids and Bases
•You can detect an acid using an indicator.
•INDICATOR - A substance that changes color in the presence of an acid or a base. INDICATORS
•Litmus paper is an indicator
●An acid turns blue litmus paper red ●A base turns red litmus paper blue
● Universal test papers can identify acids and bases INDICATORS
•Cabbage juice can also be used as an indicator. •The juice should turn pink in acidic solutions, and green/blue/yellow in basic solutions. Turn and talk- how does he do this magic trick?
https://www.youtube.com/watch?v=ujkuW-0cpNw&t=32s How do we measure the strength of an acid or base?
Use the pH (Powers of Hydrogen) scale pH scale
•Acids and Bases are ranked on a pH scale. •0-6.9 = acids, lots of H+ ions •7.1-14 = bases, lots of OH- ions Lots of H+ = Acid = low pH Lots of OH- = Base = high pH •What happens if you have a perfect balance of H+ and OH-? •HOH
•Or H2O •Water! Pure Water (H2O) is a perfect balance of the H+ ions and OH- ions
•Pure water is a 7 on the pH scale, it is called Neutral Common products and pH range Summary of Characteristics of Acid and Base Compounds
http://www.youtube .com/watch?v=tNv P3-174_M Question #1 •Lemon juice has a pH of 2.2. Is it an acid or a base?
•acid Question #2
•Detergents such as Tide have a pH of about 10. Is Tide an acid or a base? •base Question #3 •Seawater has a pH of 8.2. Is seawater an acid or a base?
•base Question #4 •The inside of your mouth has a pH of 7. Is it an acid or a base? •neutral Question #5 •How do you think we came up with the term “acid rain”?
•Rain water has a pH less than 7 Question #6 •409 cleaner contains ammonia that has a pH of 12. What will 409 do to red litmus paper? •Turn blue Question #7 •A soft drink has a pH of 3.2. What will it do to a piece of red litmus paper? •Stay red Question #8 •What is a physical or chemical property of an acid? •Tastes sour, has a pH below 7, turns litmus paper red, produces H+ ions Question #9 •What is a physical or chemical property of a base? •Tastes bitter, feels slippery, has a pH above 7, turns litmus paper blue, produces OH- ions Question #10 •What is a physical or chemical property of water? •Liquid at room temperature, colorless, has a pH of 7 (is neutral) pH of Everyday Substances
Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings Practice Acid/Base experiments http://www.kidsknowit.com/interactive-educational-movies/free-online-movies.php?movie=Acids%20And%20B ases
http://www.youtube.com/watch?v=ujkuW-0cpNw Magic tricks with Acids and Bases How can I tell if something is an acid or a base? • You can taste it (NEVER do this in a chemistry lab) • You can find its pH using a pH test paper • 0-6 = Acid 7= water/neutral 8-14= base • You can use an indicator • Red or blue litmus paper • cabbage juice indicator • Goggles on Procedures • Tear a piece of red litmus paper into three pieces and put them in the tray. Baking Vinegar Water Soda • Tear a piece of blue litmus paper into three pieces and put them in the tray. • Tear a piece of orange universal pH paper into three pieces and put them in the tray. • Drop vinegar on the first row (an acid) • Drop water on the second row (neutral) • Drop baking soda on the third row (a base) • Make observations and record data • Clean up Safety Warnings: Use your safety contract to help you. 1. Wear goggles 2. No horseplay, follow directions 3. Do not touch, taste, smell unknown liquids 4. Wear apron, roll up sleeves 5. Clean up when finished 6. Watch for broken glass, report spills Record your observations and conclusions
baking soda Unknown Acid/Base/Neutral Identification lab Worth 25 points Objectives: Can you use your knowledge of acids and B bases to identify 3 unknown substances using A indicators? C
1. Follow all previous safety guidelines 2. Read your procedures 3. Design a data table for three unknown lettered test tubes - get teacher initials 4. Conduct your testing and record your observations 5. Form your conclusions and complete review section Data –what information will you collect about the three substances? Organize a chart to put the data into. Sample A Sample B Sample C Writing a lab •Create a descriptive title for your experiment: ______•Problem: How can an unknown liquid be identified as an acid, a base, or a neutral substance? •Background Information: Acids and bases are special classes of compounds that have their own unique characteristics. Acids are ______tasting, have H+ ions, turn blue litmus paper ______, and they react with ______. Bases have a ______taste, feel slippery, have OH- ions, and turn red litmus paper ______. Materials: What materials do you need to complete this lab? Goggles, apron, beakers, red and blue litmus paper, sample tray, three unknown liquids, pH paper, droppers, lab sheet Procedures –what are the steps you need to follow to correctly identify an unknown substance as an acid or base? 1. Gather materials 2. Goggles on 3. Clean off tray 4. Tear red litmus into three pieces and put into tray 5. Repeat with blue and pH paper 6. Drop unknown chemical (A) onto red, blue, and pH paper 7. Repeat with unknown (B) and (C) liquids. 8. Record observations 9. Clean up Conclusion Statement: Following the actual performance of the lab, write a one paragraph summary about •What you did in this lab. •How you performed this lab (a summary) •What you learned as a result of performing this lab. A formally typed or very neatly handwritten lab (ON A SEPARATE PAPER!) is due! Turn in by Thurs. December 11th • It must include the following (40 points total possible): (LABEL EACH SECTION WITH THE APPROPRIATE TITLE) • Title of the lab (2 points) • Problem: describe the problem that will be solved in this lab (2 points) • Background information: one paragraph with facts about acids and bases (5 points) • Safety warnings: bulleted list of safety rules to be followed (5 points) • Materials list: bulleted list of all materials needed for the lab (2 points) • Procedures: step by step instructions (2 points) • Data: Include your table and FILL IN THE RESULTS you collected when you tested the materials (10 points) • Conclusion: A one paragraph summary of what you did, how you did it, and what you learned. (10 points) • Spelling, grammar, and overall neatness will be graded as well (2 points) Use the Rubric!