Acid rain over the Great Lakes has a pH of about 4.5. Calculate the [H3O+] concentration of this rain and compare that value to the [H3O+] concentration of rain over the West Coast, which has a pH of 5.4. How many times more concentrated is the acid in the rain over the Great Lakes compared to the rain over the West Coast?

Verified step by step guidance

Understand that pH is a measure of the hydrogen ion concentration, given by the formula \( \text{pH} = -\log[\text{H}_3\text{O}^+] \).

To find the \([\text{H}_3\text{O}^+]\) concentration for the Great Lakes rain, use the formula \([\text{H}_3\text{O}^+] = 10^{-\text{pH}}\) with \(\text{pH} = 4.5\).

Calculate \([\text{H}_3\text{O}^+]\) for the West Coast rain using the same formula with \(\text{pH} = 5.4\).

Compare the two \([\text{H}_3\text{O}^+]\) concentrations by dividing the concentration for the Great Lakes by the concentration for the West Coast.

The result of the division will tell you how many times more concentrated the acid is in the Great Lakes rain compared to the West Coast rain.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

pH Scale

The pH scale measures the acidity or basicity of a solution, ranging from 0 to 14. A pH of 7 is neutral, while values below 7 indicate acidity and above 7 indicate basicity. Each unit change in pH represents a tenfold change in hydrogen ion concentration, making it crucial for understanding the relationship between pH and [H3O+].

[H3O+] Concentration

The concentration of hydronium ions, [H3O+], in a solution is directly related to its pH. It can be calculated using the formula [H3O+] = 10^(-pH). This relationship allows us to quantify the acidity of solutions, which is essential for comparing the acidity of different rain samples.

Comparative Concentration

To compare the acidity of two solutions, one can calculate the ratio of their [H3O+] concentrations. This involves dividing the concentration of one solution by that of another. Understanding this concept is key to determining how many times more acidic one solution is compared to another, as seen in the comparison of acid rain over the Great Lakes and the West Coast.

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H₂CO₃(aq) + H₂O(l) ⇌ HCO₃^–(aq) + H₃O⁺(aq)

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