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 Base-Strong Acid

General Chemistry

18. Aqueous Equilibrium

Titrations: Weak Base-Strong Acid

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Multiple Choice

A 100.0 mL sample of 0.10 M NH3 is titrated with 0.10 M HNO3. Determine the pH of the solution after the addition of 200.0 mL of HNO3. The Kb of NH3 is 1.8 × 10^-5.

5.00

9.25

1.00

7.00

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Verified step by step guidance

Start by calculating the initial moles of NH3 in the solution. Use the formula: \( \text{moles} = \text{concentration} \times \text{volume} \). For NH3, \( \text{moles of NH3} = 0.10 \text{ M} \times 100.0 \text{ mL} \). Convert mL to L by dividing by 1000.

Next, calculate the moles of HNO3 added to the solution using the same formula: \( \text{moles of HNO3} = 0.10 \text{ M} \times 200.0 \text{ mL} \). Again, convert mL to L.

Determine the reaction between NH3 and HNO3. NH3 is a weak base and HNO3 is a strong acid. They react in a 1:1 ratio to form NH4+ and NO3-. Calculate the moles of NH3 remaining after the reaction by subtracting the moles of HNO3 from the initial moles of NH3.

Calculate the concentration of NH4+ formed in the solution. Since the total volume of the solution is now 300.0 mL (100.0 mL NH3 + 200.0 mL HNO3), use the formula: \( \text{concentration of NH4+} = \frac{\text{moles of NH4+}}{\text{total volume in L}} \).

Use the Henderson-Hasselbalch equation to find the pH of the solution. The equation is: \( \text{pH} = \text{pKa} + \log \left( \frac{[\text{base}]}{[\text{acid}]} \right) \). First, find the pKa from the Kb of NH3 using the relation \( \text{pKa} = 14 - \text{pKb} \). Then, substitute the concentrations of NH4+ and NH3 into the equation to find the pH.