To estimate the pH of an unknown lab solution, the formula pH = -log[H3O+] is used. Depending on the calculated pH, solutions can be identified as acidic, neutral, or basic. It is crucial to report the pH to the correct number of significant figures, relevant to the precision of the given data.
To estimate the pH of an unknown lab solution, we use the formula pH = -log[H3O+]. The resulting value indicates if the solution is acidic (pH < 7), neutral (pH = 7), or basic (pH > 7). For instance, a hydronium ion concentration ([H3O+]) of 9.8 × 10⁻³ gives a pH of 2.01, indicating a strongly acidic solution. On the other hand, a [H3O+] of 3.96 × 10⁻µ results in a pH of 4.4023.
Furthermore, the inverse logarithm (antilog) can calculate the [H3O+] from a known pH using a calculator's 10% key. Significantly, the reported pH values should match the significant figures of the given concentration data. For instance, if the pH is calculated as 10.99 after adding a base to an unbuffered solution, this reading is significant as it shows a substantial change compared to a buffered solution.
The final pH should be reported with the same number of significant figures as the data provided. For instance, a pH calculated as 8.30 from a hydronium concentration with two significant figures (4.7 × 10⁻⁹) should be reported with two decimal places due to the significant figures in the given concentration.
Therefore, when estimating pH, it's important to consider solution buffering, the significance of changes in pH with respect to acid or base addition, and the appropriate rounding based on significant figures in the concentration data provided.