SECTION 19.1 ACID BASE THEORIES

Transcription

1 Name: Period: Chapter 19 Acids, Bases, and Salts Final Exam Study Guide SECTION 19.1 ACID BASE THEORIES (pages ) Define the following vocabulary terms: 1. monoprotic acids 2. diprotic acids 3. triprotic acids 4. hydronium ion (H3O) 5. amphoteric Properties of Acids and Bases (pages ) 1. Circle the letters of all the terms that complete the sentence correctly. The properties of acids include. a. reacting with metals to produce oxygen b. giving foods a sour taste c. forming solutions that conduct electricity d. causing indicators to change color 2. Bases are compounds that react with acids to form and a(n). 3. Circle the letters of all the terms that complete the sentence correctly. The properties of bases include. a. tasting bitter b. feeling slippery c. changing the color of an indicator d. always acting as a strong electrolyte Arrhenius Acids and Bases (pages ) 4. Match the number of ionizable hydrogens with the type of acid. one a. diprotic two b. triprotic three c. monoprotic 5. Is the following sentence true or false? Only the hydrogens in weak polar bonds are ionizable. 6. Hydrogen is joined to a very element in a very polar bond. 7. Alkali metals react with water to produce solutions. 8. How do concentrated basic solutions differ from other basic solutions? Brønsted-Lowry Acids and Bases (pages ) 9. How does the Brønsted-Lowry theory define acids and bases? 10. Is the following sentence true or false? Some of the acids and bases included in the Arrhenius theory are not acids and bases according to the Brønsted-Lowry theory. 11. Is the following sentence true or false? A conjugate acid is the particle formed when a base gains a hydrogen ion. 12. A conjugate is the particle that remains when an acidhas donated a hydrogen ion. 13. What is a conjugate acid base pair? 14. A substance that can act as both an acid and a base is said to be. 15. In a reaction with HCl, is water an acid or a base? 1

2 SECTION 19.2 HYDROGEN IONS AND ACIDITY (pages ) Define the following vocabulary terms: 1. self-ionization 2. neutral solution 3. ion-product constant for water (Kw) 4. acidic solution 5. basic solution 6. alkaline solutions 7. ph Hydrogen Ions from Water (pages ) 1. What does a water molecule that loses a hydrogen ion become? 2. What does a water molecule that gains a hydrogen ion become? 3. The reaction in which water molecules produce ions is called the of water. 4. In water or aqueous solution, are always joined to as hydronium ions (H3O+). 5. Is the following sentence true or false? Any aqueous solution in which [H+] and [OH ] are equal is described as a neutral solution. Ion Product Constant for Water (pages ) 6. What is the ion-product constant for water (Kw)? Give the definition, the expression, and the value. 7. A(n) solution is one in which [H+] is greater than [OH ]. A(n) solution is one in which [H+] is less than [OH ]. 8. Match the type of solution with its hydrogen-ion concentration. acidic a. less than 1.0 x 10 7 M neutral b. greater than 1.0 x 10 7 M basic c. 1.0 x 10 7 M The ph Concept (pages ) 9. The of a solution is the negative logarithm of the hydrogen-ion concentration. 10. Match the type of solution with its ph. acidic a. ph greater than 7.0 neutral b. ph equal to 7.0 basic c. ph less than Look at Table 19.5 on page 598. What is the approximate [H+], the [OH ], and the ph of washing soda? 12. The poh of a solution is the negative logarithm of the concentration. 13. What is the poh of a neutral solution? 14. For ph calculations, in what form should you express the hydrogen-ion concentration? 15. Look at the ph scale below. Label where you would find acids, bases, and neutral solutions. 2

3 16. Is the following sentence true or false? Most ph values are whole numbers. 17. If [H+] is written in scientific notation but its coefficient is not 1, what do you need to calculate ph? 18. Is the following sentence true or false? You can calculate the hydrogen-ion concentration of a solution if you know the ph. Measuring ph (pages ) 19. When do you use indicators and when do you use a ph meter to measure ph? 20. Why is an indicator a valuable tool for measuring ph? 21. Why do you need many different indicators to span the entire ph spectrum? 22. Look at the figure below. Fill in the missing ph color change ranges for the indicators. 23. List three characteristics that limit the usefulness of indicators. a. b. c. 24. How accurate are measurements of ph obtained with a ph meter? 25. What is the ph of each of the following solutions? a. water b. vinegar c. milk of magnesia 26. Is the following sentence true or false? Measurements of ph obtained with a ph meter are typically accurate to within ph unit of the true ph. 3

4 ON ANOTHER PAPER, COMPLETE THE LAB WRITE-UP!!! Salt Hydrolysis Name: Period: Lab Station #: Date: Purpose: Measure the ph of aqueous solutions of several salts. Pre-Lab Notes: Neutralization of strong acids by strong bases produces neutral salts. However, salts formed in the neutralization reactions of other types of acids and bases can yield solutions that are not neutral. The salt of a strong acid and a weak base, for instance, yields an acidic solution in water. Other reactions can produce basic solutions. The acidic or basic character of these non-neutral solutions is the result of a phenomenon called salt hydrolysis. In salt hydrolysis, one of the ions of the dissolved salt reacts with water to produce hydrogen ions, H+, or hydroxide ions, OH-. In this experiment you will measure the ph of solutions of various salts. You will analyze your results to determine if one of the ions produced in solution can react with water to produce hydrogen ions H+ or hydroxide ions OH-. Procedure: 1. Wear goggles. 2. Clear your lecture table of all materials in order to make room for the lab. 3. Place a clean and dry acetate sheet on top of the data table. 4. Using tweezers, place less than a pea-size amount of the salt onto the proper test area, on the acetate sheet. Use the data table to help you indicate where to place the correct salt. 5. Take a pipette containing distilled water to your lecture table. 6. Add 1 to 2 drops of distilled water onto the salt. 7. Using a toothpick, mix thoroughly. 8. Place one drop of universal indicator onto the solutions. 9. Determine the ph of the solution by using the bottom of pg 602 Figure Repeat the process for each salt. Clean Up: 1. Return all chemicals. 2. Use paper towels to wipe down the acetate sheet. 3. Rinse the acetate sheet with tap water. 4. Dry the acetate sheet. 5. Wash your hands. 4

5 Name: Period: Pre-Lab Assignment: Salt Hydrolysis Make drawings of the following pieces of lab equipment that will be used for the laboratory: 1. Goggles: 2. Acetate sheet: 3. Tweezers: 4. Pipette containing distilled water: 5. Toothpick: 6. Universal indicator: 7. Summarize the lab clean-up process in 4 steps: a. b. c. d. 8. Take and place the pieces of chemicals on your cleared lecture table and then ask the instructor to check your lab set up. Once you have been checked off you may begin the experiment. Instructors Initials: 5

6 Name: Data: Salt Hydrolysis Salt NaCl AlCl 3 K 2CO 3 NH 4Cl NaHCO 3 Na 3PO 4 Na 2HPO 4 NaH 2PO 4 Universal Indicator Color Period: ph Acidic salt Neutral salt Basic salt NaCl AlCl 3 K 2CO 3 NH 4Cl NaHCO 3 Na 3PO 4 Na 2HPO 4 NaH 2PO 4 6

7 Conclusion Questions: 1. Which salts produced neutral aqueous solutions? (Circle Your Choice) NaCl AlCl 3 K 2CO 3 NH 4Cl NaHCO 3 Na 3PO 4 Na 2HPO 4 NaH 2PO 4 2. Which salts produced acidic aqueous solutions? (Circle Your Choice) NaCl AlCl 3 K 2CO 3 NH 4Cl NaHCO 3 Na 3PO 4 Na 2HPO 4 NaH 2PO 4 3. Which salts produced basic aqueous solutions? (Circle Your Choice) NaCl AlCl 3 K 2CO 3 NH 4Cl NaHCO 3 Na 3PO 4 Na 2HPO 4 NaH 2PO 4 NOTE: Another way to write water is: H-OH (H 2O). Water has a hydrogen ion and hydroxide ion forming a neutral solution. Therefore, water has a ph of 7 (neutral). 4. Hydrogen ions have the formula H+ and form acidic solutions. Match the salt that you think forms the following equations: a. Al(H 2O) H-OH Al(H 2O) 5OH 2+ + H 3O + Salt: b. NH H-OH NH 3 + H 3O + Salt: 5. Hydroxide ions have the formula OH- and form basic solutions. Match the salt that you think forms the following equations: a. CO H-OH HCO OH- Salt: b. HCO H-OH H 2CO 3 + OH- Salt: c. PO H-OH HPO OH- Salt: d. HPO H-OH H 2PO OH- Salt: 7

8 SECTION 19.4 NEUTRALIZATION REACTIONS (pages ) Acid Base Reactions (pages ) Define the following vocabulary terms: neutralization reactions equivalence point standard solution titration end point 1. Is the following sentence true or false? Acids react with compounds containing hydroxide ions to form water and a salt. 2. What does the reaction of an acid with a base produce? 3. In general, reactions in which an acid and a base react in an aqueous solution to produce a salt and water are called reactions. 4. Look at Table 19.9 on page 613. Circle the letter of the salt that is used for photographic emulsions. a. calcium chloride c. silver bromide b. potassium chloride d. sodium chloride 5. Salts are compounds consisting of a(n) from an acid and a(n) from a base. Titration (pages ) 6. How can you determine the concentration of an acid or base in a solution? 7. Complete the flow chart below showing the steps of a neutralization reaction. 8. The process of adding a known amount of solution of known concentration to determine the concentration of another solution is called. 9. What is the solution of known concentration called? SECTION 19.5 SALTS IN SOLUTION (pages ) Salt Hydrolysis (pages ) Define the following vocabulary terms: salt hydrolysis buffer buffer capacity 1. What is salt hydrolysis? 2. Complete this table of the rules for hydrolysis of a salt. 8

9 Buffers (pages ) 3. What are buffers? 4. A buffer is a solution of a acid and one of its salts, or a solution of a base and one of its salts. 5. Is the following sentence true or false? The buffer capacity is the amount of acid or base that can be added to a buffer solution before a significant change in ph occurs. 9

10 ON ANOTHER PAPER, COMPLETE THE LAB WRITE-UP!!! Name: Period: Lab Station #: Date: Buffers Purpose: Measure the ph changes that occur when acids and bases are added to buffered and un buffered solutions. Pre-Lab Notes: Your blood must be maintained at ph for your body to stay healthy. However, chemical reactions taking place in your body are continuously pumping a stream of hydrogen ions into your blood. Your body maintains the proper blood ph, in spite of the hydrogen ions, due to blood buffers. Buffered solutions maintain a relatively constant ph when limited amounts of acid or base are added to them. What are buffers? They usually consist of solutions of a weak acid and its salt or of a weak base and its salt. A buffer can be created by the partial neutralization of a weak acid by a strong base or by partial neutralization of a weak base by a strong acid. Procedure: 1. Wear goggles. 2. Label 3 white cups: a. #1 b. #2 c. #3 3. To the cup labeled #1, using the pipette, add 5 ml of 0.1 M sodium carbonate Na 2CO 3 and 5 ml of 0.1 M sodium bicarbonate NaHCO Mix the two solutions with a wood splint. 5. Divide this buffer solution equally between cup #1 and cup #2. 6. Add 3 drops of universal indicator to cup #1 and cup # Cup #1 Procedure Color the initial color and ph of cup #1. 8. Add 1 drop of 1 M HCl to cup #1. 9. Color the new cup color below and record the ph. 10. Add 2 drops of 1 M NaOH to cup #1 11. Color the new cup color below and record the ph Cup #2 Procedure To cup #2 add 1 M HCl until a color change occurs, count the number of drops need to get a red color change (to about a ph of 2). 13. Color the cup below and record the number of drops and the ph Cup #3 Procedure To the cup labeled #3, using a pipette, add 5 ml of 0.1M sodium bicarbonate NaHCO Add 3 drops of universal indicator. 16. Add 1 drop of 1 M HCl to cup # Color the new cup color below and record the ph. 18. Add 2 drops of 1 M NaOH to cup # Color the new cup color below and record the ph. Clean up: 1. Throw solutions in the sinks located in the lab area. Rinse with sink with water. 2. Throw rinse the white cups and the pipettes with water and replace them on the cart. 3. Replace the indicator and chemicals to the cart. Wash your hands. Name: Period: 10

11 Pre-Lab Assignment: Buffers Make drawings of the following pieces of lab equipment that will be used for the laboratory: 9. Goggles: 10. White Cups: pipettes: 12. List the name of the 2 chemicals being tested: 13. Wood Splint: 14. What is the name of the indicator being used: 15. Summarize the lab clean-up process in 4 steps: e. f. g. h. 16. Take and place the pieces of chemicals on your cleared lecture table and then ask the instructor to check your lab set up. Once you have been checked off you may begin the experiment. Instructors Initials: 11

12 Data: Buffers Name: Period: Initial Cup #1 ph = Cup #1: One Drop HCl ph = Cup #1: 2 Drops NaOH ph = Initial Cup #2 ph = Cup #2: Number of drops needed to get to red: ph = Initial Cup #3 ph = Cup #3: One Drop HCl ph = Cup #3: 2 Drops NaOH ph = 12

13 Post-Lab Questions: 1. Based on your results, which cup had a buffer solution, cup #1 or cup #3? 2. Explain your answer: 3. Cup #2 had the buffer solution as well. Based on your results, what do you conclude about buffer systems? 4. Define a buffer solution: 5. Define neutralization: 13

14 Name: Period: Video Review: Acids, Bases, and ph: 1. What are electrolytes? 2. Describe dissociation: 3. List 3 reasons why electrolytes are important in our bodies a. b. c. 4. Not only are salts electrolytes but list 2 other electrolytes: a. b. 5. Define an acid: 6. Define a base: 7. List 2 household acids: a. b. 8. List 3 household bases: a. b. 9. Most all substances have acidic or basic properties, what is the one liquid that is an exception to this rule? 10. What are the acids that the human body secretes? List and describe: a. b. 11. What is a special quality about acids and bases? 12. When H+ combines with OH- what is formed? 13. When water is formed, what is the ph of the solution? 14. Acids and bases are sorted by strong and weak, not by concentration of the solution, but by what? 15. List examples of strong acids: a. b. 16. List examples of strong bases? a. b. 17. The level of hydrogen ion concentration [H+] determines the ph value. What is ph an acronym for? 18. ph measures acidity or alkalinity (basic). Every liquid has a ph value. How does this scale range? 19. Pure water has a ph of: (neutral) 20. A ph value less than 7 is: 21. A ph value greater than 7 is: 22. Battery acid and vinegar have ph values where? 23. Baking soda and ammonia have ph values where? 24. ph scale is a log scale similar to what other scale? 25. If there is an earthquake of 7 vs 6, how many times greater is the earthquake of 7? 26. If there is a solution with a ph of 6 vs 5, how many times greater is ph of 6? 1

15 27. What percent of the human body is a fluid? 28. What is the ph value of the human body? 29. The blood is an exception to this rule. What is the ph range for blood? 30. What 6 functions of the body does is this ph essential in order for a body to be healthy? a. b. c. d. e. f. 31. What 3 body monitors help to maintain ph balance? a. b. c. 32. If ph values for the body are not with the range of 7.3 to 7.4, what are the consequences? Video Review: Buffer Demonstration: Unbuffered (distilled water) Buffered 1. What is universal indicator kinda like? 2. Color the two flasks (located above) initially before the demonstration begins. 3. What is the ph of each solution? 4. The buffered solution is 7.00, meaning that is will stay at 7.00 and resist a ph change. What does the buffer resemble? 5. What two things are in the buffer? a. b. 2

16 6. When 1 drop of acid (HCl) is added to the flask on the left (the unbuffered solution) color the flask on the left. What is the new ph: Unbuffered (distilled water) Buffered 7. When 2 drops are added to the flask on the right (the buffered solution) color the flask on the right. What is the ph: 8. Was there a change in ph to the flask on the right when an acid was added to the flask? 9. Now the demonstrator will be adding drops of HCl (acid) to the right buffered, beaker. How many drops did it take for the solution to turn yellow? 10. If the solution turns yellow, what ph is this? 11. How many drops did it take to turn orange? 12. What is the ph of the color orange? 13. How many drops did it take for the solution to be at the same ph as the flask on the left? 14. At the pink/red color, what is the ph of each flask? 15. A buffer works by resisting the change in ph. 16. When 1-2 drops of base (NaOH) are added to the flask on the left (the unbuffered solution) color the flask on the left. What is the new ph: Unbuffered (distilled water) Buffered 17. Now the demonstrator will be adding drops of NaOH (base) to the right buffered, beaker. How many drops did it take for the solution to turn yellow? 18. How many drops did it take for the solution to turn green? 19. How many drops did it take for the solution to turn purple? 20. A buffer works and is designed to hold a ph at a certain range. In this case what ph range was this buffer designed for? 3

17 Video Review: Buffer Demonstration: 1. There are two beakers, beaker A on the left side and beaker B on the right side. Universal indicator has been added to both sides. Color the two flasks (located above) initially before the demonstration begins. What are the beakers initial ph? Beaker A Beaker B 2. When one drop of base (NaOH) is added to the Beaker A on the left it changed the color of Beaker A. Color the beakers below and also indicate the ph of each beaker. Beaker A Beaker B ph = ph = 3. When one drop of acid (HCl) is added to the Beaker A on the left it changed the color of Beaker A. Color the beakers below and also indicate the ph of each beaker. Beaker A Beaker B ph = ph = 4. Explain what happens when more drops are added to the Beakers B: 4

18 5. Write the chemical symbol for an acid: 6. Write the chemical symbol for an base: 7. What is the definition of a buffer? 8. In the demonstration, which beaker was the buffer solution? 9. A buffer consists of a weak acid HA and its salt A-, its conjugate base. FAST FORWARD THE VIDEO TO 11:00 MINUTES 10. Can the buffering capacity (the ability to resist ph change) be exceeded? 11. What is the key to a buffering solution? 12. Why would one want to make a buffer solution? List 2 reasons? a. b. STOP THE VIDEO HERE Video Review: PBS Sea Change: 1. Which president, in the video, are they speaking about that left a farewell gift to the environment? 2. What percent of the earth is covered in ocean water? 3. Name 3 things that are changing the ocean and thus changing the weather/environment? a. b. c. 4. What is the name of the female ocean research scientist? 5. What is worrying these research scientists? 6. What is one of the reasons that the ocean can store so much energy? 7. What does Curry call the demonstration experiment? 8. What is demonstrating the ocean? 9. What is demonstrating the ice in the ocean? 10. What is demonstrating global warming greenhouse gases? 11. Meanwhile back on the Oceanus. What does the Moored Profiler measure? 12. Explain the conveyor belt idea relating to warm tropic water and cold arctic water: 13. In the movie The Day After Tomorrow, the conveyor stops and what happens to the earth? 14. But in reality, what happens when the ocean becomes warmer and fresher (less salty)? 15. Which species of fish is highly susceptible to warming? 16. If oceans get warmer, explain what happens to the amount of dissolved oxygen? 17. Explain what happens to lobster when the ocean heats up: 18. What kind of ocean life is experiencing the disease Durmo? 19. What happens to the ocean when there is an increase in CO 2, carbon dioxide? 20. Explain what a habitat (ecological) engineer is: 21. Where does acid rain come from: a. b. 22. Normally the ocean is buffered, but currently is the ocean becoming for basic or acidic? 23. What is the major reason for rising sea levels? 24. Back to the demonstration..what happens to the ability of the water to resist heat when there is not ice left in the beaker? 25. What happens when you have less ice and darker oceans? 26. CO 2 is called what kind of gas? Where does it come from? 5