Question

A student has a solution with a pH of 7. The student adds HF, hydrogen floride, to the solution, hoping to increases the pH of the solution. What is wrong with this student's approach?

Select one: A. You cannot change the pH of a solution. B. HF is an acid, so it will lower the pH of the solution. C. The pH of the solution is already as high as possible. D. The pH is 7, so the solution is already as acidic as possible.

Answer 1

Adding HF, which is an acid, to a solution will decrease the pH rather than increase it, as the student hoped to achieve.

Step-by-step explanation:

The student's approach to increase the pH of a solution by adding HF (hydrogen fluoride) is incorrect because HF is an acid, and adding an acid to a solution will lower the pH, not increase it. A solution with a pH of 7 is neutral. Since acids have pH values less than 7, adding HF will result in a more acidic solution with a lower pH value.

Answer 2

Low pH = high acidity.
HF has a very low pH, so when added to a solution, it will lower the pH of the solution and therefore make it more acidic. So the answer should be B.