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1. What is the pH of a solution of 0.050 M (C2H5)2NH?

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2. What is the pH of a solution of 0.050 M HClO4?

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Summary Activity

3. Label the following as acidic, basic, or neutral solutions:

KCl NaNO2 (CH3)2NH2Cl

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Which of the following is the strongest acid?

HClO2, HBrO2, HIO2

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Which of the following is the strongest acid?

H3N, H2O, HF

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What kind of substance is

C2H5NH2?

1. Strong acid2. Strong base3. Weak Acid4. Weak base

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1. What is the pH of a solution of 0.050 M (C2H5)2NH? (Kb = 4.9 10-

4)The approximation is invalid! 0.05/(4.9 10-4) = 72 ICE Table

(C2H5)2NH + H2O (C2H5)2NH2+ + OH-

I 0.050 0 0C -x +x +xE 0.050-x x x

Kb = [(C2H5)2NH2+][OH-] = x2

(C2H5)2NH 0.050-x quadraticx2 + (4.9 10-4)x – (2.45 10-5) = 0x = 4.7 10-3 = [OH-]pOH = -log(4.7 10-3) = 2.33pH = 14 – 2.33 = 11.67

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2. What is the pH of a solution of 0.050 M HClO4?Easy!! HClO4 is a strong acid, therefore [HClO4] = [H3O+] dissociated!

[H3O+] = 0.050 MpH = -log(0.050)pH = 1.30

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Summary Activity

3. Label the following as acidic, basic, or neutral solutions:

KCl NaNO2 (CH3)2NH2Cl

neutral basic acidic

K+ (cation of a strong base) neutralCl- (anion of a strong acid) neutralOverall neutral

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Summary Activity

3. Label the following as acidic, basic, or neutral solutions:

KCl NaNO2 (CH3)2NH2Cl

neutral basic acidic

Na+ (cation of a strong base) neutralNO2

- (anion of a weak acid) basicOverall basic

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Summary Activity

3. Label the following as acidic, basic, or neutral solutions:

KCl NaNO2 (CH3)2NH2Cl

neutral basic acidic

(CH3)2NH2+ (cation of a weak base—4 groups

attached to N) acidicCl- (anion of a strong acid) neutralOverall acidic

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Which of the following is the strongest acid?

HClO2, HBrO2, HIO2

Non-binary acids must consider resonance or inductive effect

not resonance 1) there are no possible resonance structures (already saturated) 2) all Lewis dot structures are equivalentinductive effect ClO2

- has Cl (which is more electronegative than Br or I). The Cl withdraws the electrons from the O atoms, stabilizing the anion making the HClO2 more acidic

O—Cl—O: ::::

:::

O—Br—O: ::::

:::

O—I—O: ::::

:::

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Which of the following is the strongest acid?

H3N, H2O, HFBinary acids must consider electronegativity or size of the anionN O F moving left to right across periodic chart

Therefore HF is strongest acid because its anion is the most electronegative atom in the group above. And the more electronegative the anion, the greater the ability to stabilize the anion, and therefore the stronger the acid

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What kind of substance is

C2H5NH2?1. Strong acid2. Strong base3. Weak Acid4. Weak base

N

C2H5

H H

:

There are 3 groups on the N, leaving the lone pair available. Therefore this amine is basic.