A C I D - B A S E T I T R A T I O N A N D p H Checking Ch 15.1 A C I D - B A S E T I T R A T I O N A N D p H

1. Amphoteric: What is the concentration of hydronium ions in pure water at 25°C? a. 0.1M b. 10-7M c. 10+7M d. 10-14M

2. Distilled water contains A.H2O. B. H3O+. C. OH−. D. All of the above

3. What is the pH of a 0.0010 M HNO3? A. 1.0 B. 3.0 C. 4.0 D. 5.0

4. Which of the following solutions would have a pH value greater than 7? A. [OH−] = 2.4 × 10−2 M B. [H3O+] = 1.53 × 10−2 M C. 0.0001 M HCl D. [OH−] = 4.4 × 10−9 M

5. If the pH of a solution of the strong base NaOH is known, which property of the solution can be calculated? A. molar concentration B. [OH−] C. [H3O+] D. All of the above

6. A neutral aqueous solution A. has a 7.0 M H3O+ concentration. B. contains neither hydronium ions nor hydroxide ions. C. has an equal number of hydronium ions and hydroxide ions. D. None of the above

7. Identify the salt that forms when a solution of H2SO4 is titrated with a solution of Ca(OH)2. A. calcium sulfate B. calcium hydroxide C. calcium oxide D. calcium phosphate

8. Which of the following is a strong acid? a. HF b. HBrO3 c. CH3COOH d. HBr

9. The pH of a solution is 6.32. What is the pOH? B. 4.8 × 10−7 C. 7.68 D. 2.1 × 10−8 Strong Acids List of the Strong Acids These are the strong acids. What makes them 'strong' is that completely dissociate into their ions (H+ and an anion) when they are mixed with water. Any other acid is a weak acid. There are only six strong acids, so you might want to commit the list of strong acids to memory. HCl - hydrochloric acid HNO3 - nitric acid H2SO4 - sulfuric acid HBr - hydrobromic acid HI - hydroiodic acid (also known as hydriodic acid) HClO4 - perchloric acid As the strong acids become more concentrated, they may be unable to fully dissociate. The rule of thumb is that a strong acid is 100% dissociated in solutions of 1.0 M or less. About: http://chemistry.about.com/od/acidsbase1/a/strong-acids-list.htm The relative stability of the conjugate base of the acid determines its acidity. Lactic acid (IUPAC systematic name: 2-hydroxypropanoic acid), also known as milk acid, is a chemical compound that plays a role in several biochemical processes. It was first isolated in 1780 by a Swedish chemist, Carl Wilhelm Scheele, and is a carboxylic acid with a chemical formula of C3H6O3. It has a hydroxyl group adjacent to the carboxyl group, making it an alpha hydroxy acid (AHA). In solution, it can lose a proton from the acidic group, producing the lactate ion CH3CH(OH)COO−. It is miscible with water or ethanol, and is hygroscopic.

10. The Kw value for water can be affected by A. dissolving a salt in the solution. B. changes in temperature. C. changes in the hydroxide ion concentration. D. the presence of a strong acid.

11. Which of the pH levels listed below is the most acidic? A. pH = 1 B. pH = 5 C. pH = 9 D. pH = 13

12. A solution has a pH of 4.75. What is the hydronium ion concentration? a. 5.623 x 104 b. 1.78 x 10-5 c. 4.75 x 101 d. 5.624 x 10-10

13. What is the concentration of hydronium ions in pure water? a. 1.0 10-7 M b. c. the same as [OH-] d. All of the above

1. Calculating pH from [H3O+] pH = −log [H3O+] practice 15C #1 (p506) What is the pH of a solution if the [H3O+] is 6.7 × 10−4 M? (key strokes for TI 80’s) Change the sign (+/−); Key log; key in the number: 6.7; 2nd/log key in exponent-4 enter; pH = 3.17; pOH = 10.83 do the other three include the pOH [OH-] = (1.0 x 10-14)/ [H3O] = [OH-] = (1.0 x 10-14)/ [6.7 × 10−4 ]=1.43x10-11 M Calculating [H3O+] from pH Determine [H3O+] M from pH 3.67 ; pOH = (14-3.67)= 10.33 [H3O+]=2nd log, key in 3.67 enter = 4.68x10-3M [OH] = (1.0 x 10-14)/ [H3O] = [OH-] = ( 1.0 x 10-14 )/ [ 4.68x10-3 ]=2.14x10-12 M

2. Calculating [H3O+] from pH If you rearrange pH = −log [H3O+] to solve for [H3O+], the equation becomes [H3O+] = 10−pH • Change the sign of the pH (+/−) • Raise 10 to the negative pH power (take the antilog). • The result is [H3O+]. So lets find the concentrations of KOH, a strong base, from the pOH of 3.45; answer: pH=10.55; basic, alkaline; [H3O+]=2.818x10-11 M; pOh=3.45; [OH-]=3.55x10-4M