Table of contents

1. Intro to General Chemistry3h 48m
2. Atoms & Elements4h 16m
3. Chemical Reactions4h 10m
4. BONUS: Lab Techniques and Procedures1h 38m
5. BONUS: Mathematical Operations and Functions48m
6. Chemical Quantities & Aqueous Reactions3h 53m
7. Gases3h 49m
8. Thermochemistry2h 37m
9. Quantum Mechanics2h 58m
10. Periodic Properties of the Elements3h 9m
11. Bonding & Molecular Structure3h 29m
12. Molecular Shapes & Valence Bond Theory1h 57m
13. Liquids, Solids & Intermolecular Forces2h 23m
14. Solutions3h 1m
15. Chemical Kinetics2h 53m
16. Chemical Equilibrium2h 29m
17. Acid and Base Equilibrium5h 1m
18. Aqueous Equilibrium4h 47m
19. Chemical Thermodynamics1h 50m
20. Electrochemistry2h 42m
21. Nuclear Chemistry2h 36m
22. Organic Chemistry5h 7m
23. Chemistry of the Nonmetals2h 39m
24. Transition Metals and Coordination Compounds3h 16m

18. Aqueous Equilibrium

Titrations: Weak Acid-Strong Base

General Chemistry

18. Aqueous Equilibrium

Titrations: Weak Acid-Strong Base

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Multiple Choice

Consider the titration of 25.00 mL of 0.150 M hydrazoic acid (Ka = 1.90 × 10^-5) with 0.200 M NaOH. What is the pH of the solution after the addition of 15.00 mL of NaOH solution?

7.00

6.25

5.10

4.75

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Verified step by step guidance

Calculate the initial moles of hydrazoic acid (HN3) using the formula: \( \text{moles of HN3} = \text{volume (L)} \times \text{molarity (M)} \). Convert 25.00 mL to liters and multiply by 0.150 M.

Calculate the moles of NaOH added using the formula: \( \text{moles of NaOH} = \text{volume (L)} \times \text{molarity (M)} \). Convert 15.00 mL to liters and multiply by 0.200 M.

Determine the moles of HN3 remaining after reaction with NaOH. Since NaOH is a strong base, it will react completely with HN3. Subtract the moles of NaOH from the initial moles of HN3 to find the moles of HN3 remaining.

Calculate the concentration of the remaining HN3 in the solution. Add the volumes of HN3 and NaOH to find the total volume of the solution in liters. Use the formula: \( \text{concentration of HN3} = \frac{\text{moles of HN3 remaining}}{\text{total volume (L)}} \).

Use the Henderson-Hasselbalch equation to find the pH of the solution: \( \text{pH} = \text{pKa} + \log \left( \frac{[\text{A}^-]}{[\text{HA}]} \right) \). Calculate \( \text{pKa} \) from \( \text{Ka} \) using \( \text{pKa} = -\log(\text{Ka}) \), and substitute the concentrations of the conjugate base \([\text{A}^-]\) and the weak acid \([\text{HA}]\) into the equation.