Chemistry lab question:   Part C: Using table 1, identify the unknown base *l have included part a and b, which includes the pOH and Kb. I will also attach table 1.

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Chemistry lab question:

 

Part C: Using table 1, identify the unknown base

*l have included part a and b, which includes the pOH and Kb. I will also attach table 1. 

### Table 1: Ionization Constants for Some Weak Acids and Bases at 25 °C

#### Acids

| Acid                           | Formula     | \(K_a\)             |
|--------------------------------|-------------|---------------------|
| Acetic acid                    | CH₃COOH     | 1.8 × 10⁻⁵          |
| Benzoic acid                   | C₆H₅COOH    | 6.3 × 10⁻⁵          |
| Carbonic acid                  | H₂CO₃       | 4.2 × 10⁻⁷          |
| Formic acid                    | HCOOH       | 1.8 × 10⁻⁴          |
| Hypochlorous acid              | HOCl        | 3.5 × 10⁻⁸          |
| Dihydrogen phosphate ion       | H₂PO₄⁻      | 6.2 × 10⁻8          |
| Hydrogen phosphate ion         | HPO₄²⁻      | 3.6 × 10⁻¹³         |
| Hydrogen carbonate ion         | HCO₃⁻       | 4.8 × 10⁻¹¹         |
| Nitrous acid                   | HNO₂        | 4.8 × 10⁻⁴          |
| Phenol                         | C₆H₆O       | 1.0 × 10⁻¹⁰         |
| Potassium hydrogen phthalate   | KC₈H₅O₄     | 5.3 × 10⁻⁶          |
| Ammonium chloride              | NH₄Cl       | 5.6 × 10⁻¹⁰         |

#### Bases

| Base                           | Formula     | \(K_b\)             |
|--------------------------------|-------------|---------------------|
| Aqueous ammonia                | NH₃         | 1.8 × 10⁻⁵          |
| Acetate ion                    | CH₃COO⁻     | 5.6 × 10⁻¹⁰         |
| Formate ion                    | HCOO⁻       | 5.9 × 10⁻¹¹         |
| Hydrogen carbonate ion         | HCO₃⁻       | 2.4 ×
Transcribed Image Text:### Table 1: Ionization Constants for Some Weak Acids and Bases at 25 °C #### Acids | Acid | Formula | \(K_a\) | |--------------------------------|-------------|---------------------| | Acetic acid | CH₃COOH | 1.8 × 10⁻⁵ | | Benzoic acid | C₆H₅COOH | 6.3 × 10⁻⁵ | | Carbonic acid | H₂CO₃ | 4.2 × 10⁻⁷ | | Formic acid | HCOOH | 1.8 × 10⁻⁴ | | Hypochlorous acid | HOCl | 3.5 × 10⁻⁸ | | Dihydrogen phosphate ion | H₂PO₄⁻ | 6.2 × 10⁻8 | | Hydrogen phosphate ion | HPO₄²⁻ | 3.6 × 10⁻¹³ | | Hydrogen carbonate ion | HCO₃⁻ | 4.8 × 10⁻¹¹ | | Nitrous acid | HNO₂ | 4.8 × 10⁻⁴ | | Phenol | C₆H₆O | 1.0 × 10⁻¹⁰ | | Potassium hydrogen phthalate | KC₈H₅O₄ | 5.3 × 10⁻⁶ | | Ammonium chloride | NH₄Cl | 5.6 × 10⁻¹⁰ | #### Bases | Base | Formula | \(K_b\) | |--------------------------------|-------------|---------------------| | Aqueous ammonia | NH₃ | 1.8 × 10⁻⁵ | | Acetate ion | CH₃COO⁻ | 5.6 × 10⁻¹⁰ | | Formate ion | HCOO⁻ | 5.9 × 10⁻¹¹ | | Hydrogen carbonate ion | HCO₃⁻ | 2.4 ×
### Chemistry Titration Problem

#### Problem Statement:
1. **Unknown base solution** = 10ml

#### (a) Titration with Hydrochloric Acid:
- **Titrated with known concentration** of HCl of molar volume = 0.100M.
- **Given graph equivalence point** = pH 3.92.
- To find:
  - **Kb** = ?
  - **pOH** = ?

**Half Equivalence Point:**
- At the half equivalence point, pH = pKa.
- Relationship:
  \[ \text{pKa} + \text{pKb} = 14 \]

Given:
\[ \text{pKa} = 3.92 \]
\[ \text{pKb} = 14 - 3.92 = 10.08 \]

Therefore:
\[ \text{pOH} = 10.08 \]

Subsequently, the OH⁻ concentration is:
\[ \text{[OH]⁻} = 10^{-10.08} \]

#### (b) Dissociation of NaOH:

The dissociation equation of NaOH is:
\[ \text{NaOH} \leftrightarrow \text{Na}^+ + \text{OH}^- \]

Initial concentrations:
\[ \text{NaOH} = 0.100 \,M \]
\[ \text{Na}^+ = 0 \]
\[ \text{OH}^- = 0 \]

Changes in concentrations:
\[ \text{NaOH}: (0.100 - x) \]
\[ \text{Na}^+: x \]
\[ \text{OH}^-: x \]

At equilibrium:
\[ \text{[OH]⁻} = x = 10^{-10.08} \]

The base dissociation constant (Kb) is given by:
\[ K_b = \frac{x^2}{0.100 - x} \]
Substituting values:
\[ K_b = \frac{(10^{-10.08})^2}{0.100 - 10^{-10.08}} \]

Performing the calculation:
\[ K_b \approx 1.6 \times 10^{-4} \]

#### (c)

*Note: The third part of the problem is not included in the provided text.*

### Key Points:
- pH at
Transcribed Image Text:### Chemistry Titration Problem #### Problem Statement: 1. **Unknown base solution** = 10ml #### (a) Titration with Hydrochloric Acid: - **Titrated with known concentration** of HCl of molar volume = 0.100M. - **Given graph equivalence point** = pH 3.92. - To find: - **Kb** = ? - **pOH** = ? **Half Equivalence Point:** - At the half equivalence point, pH = pKa. - Relationship: \[ \text{pKa} + \text{pKb} = 14 \] Given: \[ \text{pKa} = 3.92 \] \[ \text{pKb} = 14 - 3.92 = 10.08 \] Therefore: \[ \text{pOH} = 10.08 \] Subsequently, the OH⁻ concentration is: \[ \text{[OH]⁻} = 10^{-10.08} \] #### (b) Dissociation of NaOH: The dissociation equation of NaOH is: \[ \text{NaOH} \leftrightarrow \text{Na}^+ + \text{OH}^- \] Initial concentrations: \[ \text{NaOH} = 0.100 \,M \] \[ \text{Na}^+ = 0 \] \[ \text{OH}^- = 0 \] Changes in concentrations: \[ \text{NaOH}: (0.100 - x) \] \[ \text{Na}^+: x \] \[ \text{OH}^-: x \] At equilibrium: \[ \text{[OH]⁻} = x = 10^{-10.08} \] The base dissociation constant (Kb) is given by: \[ K_b = \frac{x^2}{0.100 - x} \] Substituting values: \[ K_b = \frac{(10^{-10.08})^2}{0.100 - 10^{-10.08}} \] Performing the calculation: \[ K_b \approx 1.6 \times 10^{-4} \] #### (c) *Note: The third part of the problem is not included in the provided text.* ### Key Points: - pH at
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