Question

# What is the pH of a 0.15 M solution of HClO? Ka for HClO = 3.5...

1. What is the pH of a 0.15 M solution of HClO? Ka for HClO = 3.5 x 10-8
1. The value of Ka for the weak acid Benzoic acid (C6H6COOH) is 1.5 × 10-5. What are the equilibrium concentrations of all species if 1.50 g of Benzoic acid is dissolved in enough water to make a 250.0 mL solution? What is the pH of the solution?
1. Ammonium ion is the conjugate acid of Ammonia.   What is the pH of a 0.25 M solution of NH4Cl?   The K­b for Ammonia, NH3, is 1.8 × 10-5.

Steps:

1. What is the balanced chemical reaction?
2. Set up Ka expression:
3. Determine the value of Ka for the conjugate acid from the Kb given
4. Determine the initial concentrations of each species present:
5. Set up table:
 initial concentration (M) change in conc (M) equilibrium conc (M)
1. Solve for Q to determine the direction of the reaction:
2. Solve for the equilibrium concentrations in terms of x:
3. Solve for x: (Can you make the assumption that x is small compared to the initial concentrations?)
4. Determine the % reaction to verify assumption if made:
5. Check your equilibrium concentrations in Ka to determine if answers are correct.
6. Calculate pH from the equilibrium concentration of H3O+  #### Earn Coins

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