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

17. Acid and Base Equilibrium

pH of Weak Acids

General Chemistry

17. Acid and Base Equilibrium

pH of Weak Acids

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Multiple Choice

An 8.36 g sample of NH4Cl was added to 26.0 mL of 1.00 M NaOH and the resulting solution diluted to 0.100 L. What is the pH of this buffer solution?

5.75

7.00

11.00

9.25

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Verified step by step guidance

Calculate the moles of NH4Cl using its molar mass. The molar mass of NH4Cl is approximately 53.49 g/mol. Use the formula: moles = mass / molar mass.

Calculate the moles of NaOH using its concentration and volume. Use the formula: moles = concentration (M) × volume (L). Convert the volume from mL to L before using it in the calculation.

Determine the limiting reactant between NH4Cl and NaOH. The reaction between NH4Cl and NaOH produces NH3 and H2O. Compare the moles of NH4Cl and NaOH to find which one is the limiting reactant.

Calculate the concentration of NH3 in the final solution. Subtract the moles of the limiting reactant from the other reactant to find the moles of NH3 formed. Then, divide by the total volume of the solution (0.100 L) to find the concentration.

Use the Henderson-Hasselbalch equation to find the pH of the buffer solution. The equation is: pH = pKa + log([base]/[acid]). Use the concentration of NH3 as the base and the concentration of NH4+ (from NH4Cl) as the acid. The pKa of NH4+ is approximately 9.25.