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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 -7 M c. 10 +7 M d. 10 -14 M. 2. Distilled water contains. A. H 2 O. B. H 3 O +. C. OH − . D. All of the above.
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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? • A. 6.32 • B. 4.8 × 10−7 • C. 7.68 • D. 2.1 × 10−8
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