A few questions on pH < before a test

[peter444]

1. what is the pH of a solution that contains 1.56X 10^5 M hydrogen ions ?
2. Is there a pH above which the molarity of hydrogen of water is higher that the molarity of hydrogen ions derived from the dissolved chemical, and what is it?
3. What is the pH of 10^-8 M solution of HCl, when HCl fully dissociates in aqueous solution?

Thanks

 

[Sirus]

Don't really get the second question.

For 1 and 3, you should have gotten equations that relate hydrogen ion concentration and pH. Once you have that, 1 is easy, and for three, consider what [H^{+}] is when HCl fully dissociates.

 

[wais]

for your questions on pH! Let's dive in and answer them one by one.

1. The pH of a solution is a measure of its acidity or basicity, and it is determined by the concentration of hydrogen ions (H+) in the solution. The pH scale ranges from 0 to 14, with 7 being neutral, below 7 being acidic, and above 7 being basic. To find the pH of a solution, we use the formula pH = -log[H+], where [H+] represents the concentration of hydrogen ions in moles per liter (M). In this case, the solution has a concentration of 1.56X 10^5 M hydrogen ions, so the pH would be -log(1.56X 10^5) = 4.81.

2. Yes, there is a pH above which the molarity of hydrogen ions from water is higher than the molarity of hydrogen ions from a dissolved chemical. This pH is 7, which is considered neutral. At a pH of 7, the concentration of hydrogen ions from water is 10^-7 M, while the concentration of hydrogen ions from a dissolved chemical may be lower. This is because water molecules can also dissociate into hydrogen ions and hydroxide ions, contributing to the overall concentration of hydrogen ions in the solution.

3. When HCl (hydrochloric acid) fully dissociates in aqueous solution, it breaks down into H+ and Cl- ions. This means that the concentration of H+ ions in the solution is equal to the concentration of HCl in moles per liter. In this case, the solution has a concentration of 10^-8 M HCl, so the concentration of H+ ions is also 10^-8 M. Using the pH formula, we get a pH of -log(10^-8) = 8. This solution would be considered acidic, as it has a pH below 7.