Hydronium Ion Concentration and pH

The video tutorial explains how to calculate the pH of a very dilute HCl solution. Initially, the pH is calculated using the standard formula, resulting in an incorrect value greater than 7. The tutorial identifies the oversight of ignoring the contribution of hydronium ions from the autolysis of water. By considering this contribution, the correct pH is recalculated to be 6.96, demonstrating the importance of accounting for all sources of hydronium ions in dilute solutions.

What is the initial incorrect pH value calculated for the 10^-8 M HCl solution?

• 8

• 7

• 5

• 6

Why is the initial pH calculation of 8 considered incorrect for an acidic solution?

• Because pH cannot be calculated for dilute solutions

• Because pH of an acidic solution should be less than 7

• Because the concentration of HCl was too high

• Because the formula used was incorrect

What is the contribution of water to the hydronium ion concentration at 25°C?

• 10^-9 M

• 10^-8 M

• 10^-7 M

• 10^-6 M

In which cases is the contribution of water to hydronium ion concentration usually ignored?

• When the molarity is 10^-8 M or less

• When the molarity is exactly 10^-7 M

• When the solution is neutral

• When the molarity is 10^-6 M or more

What is the total hydronium ion concentration when considering both HCl and water contributions?

• 1.3 x 10^-7 M

• 1.0 x 10^-7 M

• 1.2 x 10^-7 M

• 1.1 x 10^-7 M

Why can't the contribution of water be ignored in the case of 10^-8 M HCl solution?

• Because it is greater than the contribution from HCl

• Because it is negligible

• Because it is less than the contribution from HCl

• Because it is equal to the contribution from HCl

What is the corrected pH value after considering the total hydronium ion concentration?

• 7.00

• 6.90

• 6.96

• 6.80

How is the pH calculated using the total hydronium ion concentration?

• By multiplying the concentration by 10

• By subtracting the concentration from 14

• By adding the concentration to 7

• By taking the negative log of the concentration

What is the log value of 1.1 used in the final pH calculation?

• 0.01

• 0.02

• 0.03

• 0.04

What is the significance of considering the autolysis of water in pH calculations of very dilute solutions?

• It has no effect on the pH

• It provides a more accurate pH value

• It decreases the pH significantly

• It increases the pH significantly