Problem 13 - Chemistry A Molecular Approach

Question

Sulfuric acid is a component of acid rain formed when gaseous sulfur dioxide pollutant reacts with gaseous oxygen and liquid water to form aqueous sulfuric acid. Write the balanced chemical equation for this reaction. (Note: This is a simplified representation of this reaction.)

Step-by-Step Solution

Answer

The balanced chemical equation for the formation of sulfuric acid from sulfur dioxide, oxygen, and water is: 2 SO2 + O2 + 2 H2O -> 2 H2SO4.

Step 1: Write the Unbalanced Chemical Equation

Start by writing down the chemical formulas of the reactants and products. Sulfur dioxide (SO2), oxygen (O2), and water (H2O) are the reactants, and sulfuric acid (H2SO4) is the product. The unbalanced chemical equation is: SO2 + O2 + H2O -> H2SO4

Step 2: Balance the Sulfur Atoms

There is 1 sulfur atom on each side of the equation, so sulfur is already balanced.

Step 3: Balance the Oxygen Atoms

There are 2 oxygen atoms from SO2, 2 from O2, and 1 from H2O on the reactant side (total 5), and 4 oxygen atoms in H2SO4 on the product side. To balance, you can place a coefficient of 2 in front of H2SO4 to have a total of 4 oxygen atoms from SO2 and O2, and an additional half O2 to contribute the last oxygen, balancing it to 8 on both sides. The equation now looks like: SO2 + O2 + H2O -> 2 H2SO4

Step 4: Balance the Hydrogen Atoms

There are 2 hydrogen atoms from H2O on the reactant side and 4 hydrogen atoms in the products (because of the coefficient of 2 in front of H2SO4). Balance the hydrogens by placing a coefficient of 2 in front of H2O. The almost balanced equation is: SO2 + O2 + 2 H2O -> 2 H2SO4

Step 5: Ensure All Coefficients are Whole Numbers

The equation from Step 4 actually has a fractional coefficient for O2, which is not conventional in a balanced chemical equation. To get rid of the fraction, multiply every coefficient by 2 to get whole numbers. The balanced chemical equation is: 2 SO2 + O2 + 2 H2O -> 2 H2SO4

Step 6: Final Check

Verify that the atoms are balanced on both sides: 4 sulfur atoms, 6 oxygen atoms from SO2 and O2 and 4 from H2O (10 in total), and 4 hydrogen atoms on both sides.

Key Concepts

Acid Rain Chemistry

The phenomenon commonly known as acid rain is a form of environmental pollution that has damaging effects on ecosystems, human health, and man-made structures. The chemistry of acid rain involves the reaction of certain airborne compounds with atmospheric moisture to create acids that eventually fall to Earth. Principal among these compounds is sulfur dioxide (SO₂), which predominantly originates from the burning of fossil fuels like coal and oil in power plants.

When SO₂ enters the atmosphere, it undergoes a series of complex reactions involving oxygen (O₂) and water (H₂O) to form sulfuric acid (H₂SO₄). The chemical transformation, facilitated by sunlight and other atmospheric particles, eventually leads to the acidic precipitation colloquially referred to as acid rain. This rain can significantly lower the pH of natural water bodies and soils, leading to detrimental effects on aquatic life, forestation, and the integrity of buildings and monuments.

Chemical Reaction Steps

Balancing a chemical equation is a fundamental skill in the study of chemistry. It involves following specific steps to ensure that the number of atoms of each element is the same on both sides of the equation, thereby obeying the Law of Conservation of Mass.

Identify Reactants and Products

Initially, one lists the reactants and products and their respective chemical formulas. This step determines the substances involved before any changes occur.

Determine the Atomic Inventory

Next, the number of atoms of each element in the reactants and products is tallied, which becomes the basis for comparison and adjustment.

Balance Elements One by One

Typically, one starts by balancing the more complex molecule or the element that appears in the least compounds. Progressively, you balance the remaining elements, excluding elements that appear only once on each side, which are often balanced last.

Adjust the Coefficients

Adjusting the coefficients—whole number multipliers of the molecules—is crucial to obtaining the same number of atoms for each element on both sides.

Validate the Equation

Finally, a double-check ensures that no mistakes were made and all elements are balanced, signifying a correctly balanced equation.

Sulfuric Acid Formation

The formation of sulfuric acid (H₂SO₄) in the atmosphere is a key example of chemical transformation with significant environmental implications. Sulfur dioxide (SO₂) gas released from various industrial activities reacts with oxygen and water vapor through a series of intermediate steps to form sulfuric acid. This process, while seemingly straightforward, involves a careful balance of atoms during reaction.

It is crucial to remember that balancing a chemical equation such as SO₂ + O₂ + H₂O -> H₂SO₄ requires attention to the stoichiometric coefficients. These coefficients ensure that the number of atoms for each element is conserved. Given SO₂ and O₂ as reactants, and H₂SO₄ as the product, the formation of sulfuric acid in the presence of water can be visualized as a balancing act that maintains the atomic tally on both sides of the equation.

By meticulously following the aforementioned chemical reaction steps to achieve a balanced equation, one not only gains insights into the chemistry of acid rain but also enhances the understanding of fundamental chemical processes that govern our environment.