To determine which solution has a pH equal to 1, we need to analyze the concentrations of HCl and NaOH in each mixture. A pH of 1 indicates a highly acidic solution, which means there should be an excess of HCl over NaOH.
Analyzing Each Mixture
- Solution A: 60 mL M/10 HCl + 40 mL M/10 NaOH
- Solution B: 55 mL M/10 HCl + 45 mL M/10 NaOH
- Solution C: 75 mL M/5 HCl + 25 mL M/5 NaOH
- Solution D: 100 mL M/10 HCl + 100 mL M/10 NaOH
Calculating the pH
To find the pH, we need to calculate the moles of HCl and NaOH in each solution:
- **Solution A:**
- HCl: 60 mL × (1/10) mol/L = 0.006 mol
- NaOH: 40 mL × (1/10) mol/L = 0.004 mol
- Excess HCl = 0.006 - 0.004 = 0.002 mol
- **Solution B:**
- HCl: 55 mL × (1/10) mol/L = 0.0055 mol
- NaOH: 45 mL × (1/10) mol/L = 0.0045 mol
- Excess HCl = 0.0055 - 0.0045 = 0.001 mol
- **Solution C:**
- HCl: 75 mL × (1/5) mol/L = 0.0075 mol
- NaOH: 25 mL × (1/5) mol/L = 0.0025 mol
- Excess HCl = 0.0075 - 0.0025 = 0.005 mol
- **Solution D:**
- HCl: 100 mL × (1/10) mol/L = 0.01 mol
- NaOH: 100 mL × (1/10) mol/L = 0.01 mol
- Excess HCl = 0.01 - 0.01 = 0 mol
Identifying the Solution with pH 1
For a solution to have a pH of 1, it must have a concentration of H+ ions of 0.1 M. This corresponds to 0.1 moles in 1 L of solution. The only solution with a significant excess of HCl is:
Solution C with 0.005 mol of excess HCl in a total volume of 100 mL (0.1 L), which gives a concentration of 0.05 M. However, none of the solutions reach the required concentration for a pH of 1.
Thus, none of the provided solutions will have a pH equal to 1.
