ma Recitation quiz 4 key

# ma Recitation quiz 4 key - don’t affect the pH 4 A...

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Chemistry 106 Recitation 2-10 Name: Section: 1. (2 points) Name 7 strong acids - HNO 3 - HCL - HBR - HI - H 2 SO 4 - HClO 4 - HClO 3 2. The pH of a .25 M solution of LiZ is 12.3. a. (1 points) (Circle one) LiZ is a(n) acid base b. (2 points) What is the K a of the HZ? Z - + H 2 O HZ + OH - K b = .02 2 = 1.73 E -3 . . . . . K w = 5.78 E -12 I .25 ------- O O (.25-.02) K b C -x -------- +x +x E .25-.02 ------- .02 .02 The reason the ice table solves for a K b is because that the reactant is a base. Whatever your weak is on the reactants is what you solve for or the K value that you have to use 3. (2 points) Complete each sentence with “increases,” “decreases,” or “doesn’t affect.” a. Cl - in solution doesn’t affect the pH b. Anions of weak acids increase the [OH - ] c. Iron (II) ions in solution increase the [H + ] d. Cations of strong acids
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Unformatted text preview: don’t affect the pH 4. A solution contains 0.317 moles of HCOOH (K a = 1.8 × 10-4 ) and .310 moles of COOH. a. (2 points) What is the pH of this solution? pK a + log (base/acid) = pH 3.744 + log(.31/.317) = 3.73=pH You can use Henderson Hasselbalch equation because both weak acid and base are present b. (1 points) Briefly explain, in your own words, the concept of a “buffer solution.” A buffer solution is one in which there are a conjugate pair of weak acid and weak base in solution. The acid and base help to neutralize any change in pH thereby making the solution relatively resistant to a change in pH. Weak Acid helps to neutralize added base and weak base helps to neutralize added acid...
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