Question

Consider two solutions at 25°C, solution A and solution B. [H+] in solution A is 200 times greater than that in solution B. What is the difference in the pH values of the two solutions?

Answer 1

The pH value of Solution A is approximately 2.3 units lower than that of Solution B, due to the 200 times higher hydrogen ion concentration in Solution A, as the pH scale is logarithmic.

Step-by-step explanation:

To understand the difference in pH values between two solutions with varying [H+] concentrations, we must first recognize that the pH scale is logarithmic. This means that each whole number change in pH represents a tenfold change in hydrogen ion concentration.

If Solution A has a [H+] concentration that is 200 times greater than Solution B, we can calculate the difference in their pH values. Since each tenfold increase corresponds to a decrease of 1 pH unit, a hundredfold increase (10×10) would be a decrease of 2 pH units. Therefore, a 200-fold increase is slightly more than two pH units, specifically, log(200) which is approximately 2.3.

Putting it together, Solution A's pH value would be about 2.3 units lower than that of Solution B, assuming the difference in concentration can be expressed precisely as 200 times.