Question

The presence of SO2 in the atmosphere and the sulfuric acid that it produces result in the phenomenon of acid rain. Uncontaminated rainwater is naturally acidic and generally has a pH value of about 5.6. The pH of acid rain is about 4. This acidity has affected many lakes in northern Europe, the northern United States, and Canada, reducing fish populations and affecting other parts of the ecological network within the lakes and surrounding forests.

Part A
If the pH of a 1.00-in. rainfall over 1700 miles^2 is 3.20, how many kilograms of sulfuric acid, H2SO4, are present, assuming that it is the only acid contributing to the pH? For sulfuric acid, Ka1 is very large and Ka2 is 0.012.
Express your answer to two significant figures and include the appropriate units.
View Available Hint(s)
The pH of most natural waters containing living organisms is between 6.5 and 8.5, but freshwater pH values are far below 6.5 in many parts of the continental United States. At pH levels below 4.0, all vertebrates, most invertebrates, and many microorganisms are destroyed. More than 300 lakes in New York State contain no fish, and 140 lakes in Ontario, Canada, are devoid of life. The acid rain that appears to have killed the organisms in these lakes originates hundreds of kilometers upwind in the Ohio Valley and Great Lakes regions. Some of these regions are recovering as sulfur emissions from fossil fuel combustion decrease, in part because of the U.S. Clean Air Act of 1990, which required that power plants reduce their sulfur emissions by 80%.

Answer 1

The amount of sulfuric acid present in the given rainfall is 3.9 * 10^(-5) kg.

Step-by-step explanation:

Acid rain is rainwater that has a pH of less than 5, due to a variety of nonmetal oxides being dissolved in the water and reacting with it to form sulfuric acid. The formation and subsequent ionization of sulfuric acid is shown by the equations:

H₂O(l) + SO₃(g) → H₂SO₄(aq)

H₂SO₄(aq) → H⁺(aq) + HSO₄⁻(aq)

To calculate the amount of sulfuric acid in a given rainfall, you can use the equation:

pH = -log[H⁺]

Using the given pH of 3.20, you can find the concentration of [H⁺], and since 1 mole of sulfuric acid produces 2 moles of H⁺, you can determine the amount of H₂SO₄ present. Finally, using the formula mass of H₂SO₄, you can convert the moles of acid to kilograms.

The formula mass of H₂SO₄ is 98.09 g/mol, so the molar mass is 0.09809 kg/mol.

Using the equation: mol H₂SO₄ = (10^(-pH))*volume of the rainfall in liters

mol H₂SO₄ = (10^(-3.20))*(1.00 in^3)*(1 L/61.03 in^3)

mol H₂SO₄ = 3.9810 * 10^(-4) mol

mass H₂SO₄ = (3.9810 * 10^(-4) mol)*(0.09809 kg/mol)

mass H₂SO₄ = 3.90417 * 10^(-5) kg

Rounded to two significant figures, the amount of sulfuric acid present in the given rainfall is 3.9 * 10^(-5) kg.