Question

Balance the equation for the reaction in which hot, concentrated sulfuric acid reacts with zinc to form zinc sulfate, hydrogen sulfide, and water.

Short answer

Zn + 4 H₂SO₄ → ZnSO₄ + H₂S + 4 H₂O

Step-by-step solution

Write the unbalanced equation

Write down the skeletal chemical equation for the reaction. In this case, the reaction is between sulfuric acid (H₂SO₄) and zinc (Zn), forming zinc sulfate (ZnSO₄), hydrogen sulfide (H₂S), and water (H₂O).The unbalanced equation is:Zn + H₂SO₄ → ZnSO₄ + H₂S + H₂O

Count the atoms

Count the number of atoms of each element on both sides of the equation to determine where the imbalance lies:Reactants: - Zn: 1- H: 2- S: 1- O: 4Products: - Zn: 1- H: 4- S: 2- O: 5

Balance the atoms one at a time

Start balancing each element one at a time, beginning with those appearing in only one reactant and one product. Here, begin with hydrogen and then proceed to sulfur and oxygen.First, balance hydrogen (H):Zn + 4 H₂SO₄ → ZnSO₄ + H₂S + 4 H₂O

Verify if all atoms are balanced

Check the number of atoms for each element to see if they are balanced:Reactants: - Zn: 1- H: 8 (4 H₂SO₄ * 2 H each)- S: 4 (4 H₂SO₄ * 1 S each)- O: 16 (4 H₂SO₄ * 4 O each)Products: - Zn: 1- H: 8 (4 H₂O * 2 H each + 1 H₂S * 2 H each)- S: 2 (1 ZnSO₄ * 1 S each + 1 H₂S * 1 S each)- O: 5 (1 ZnSO₄ * 4 O each + 4 H₂O * 1 O each)

Adjust coefficients to fully balance the equation

In previous step we see the balance in terms of S and O is not satisfied. Therefore, adjusting S and O in product side to balance the whole equation completely:Zn + 4 H₂SO₄ → ZnSO₄ + H₂S + 4 H₂O

Key concepts

chemical reactions

A chemical reaction is when substances, called reactants, are transformed into new substances, known as products. In the case given, the reactants are sulfuric acid (H₂SO₄) and zinc (Zn), which react to form zinc sulfate (ZnSO₄), hydrogen sulfide (H₂S), and water (H₂O). Chemical reactions involve breaking old bonds and forming new ones. This results in a change in the chemical composition of the substances involved. They are typically represented using chemical equations where the reactants are on the left side and the products on the right side.

stoichiometry

Stoichiometry is the study of the quantitative relationships between the reactants and products in a chemical reaction. It is based on the balanced chemical equation from the reaction. This concept helps us understand how much of each reactant is needed and how much of each product is formed. It uses the coefficients (the numbers in front of molecules in a balanced equation) to determine the proportions of reactants and products. In the given reaction, stoichiometry tells us the ratio in which zinc and sulfuric acid react to form zinc sulfate, hydrogen sulfide, and water. By balancing the equation, we can apply stoichiometric principles to calculate the amounts of substances involved.

atom conservation

One of the fundamental concepts in balancing chemical equations is atom conservation. This law states that atoms are neither created nor destroyed in a chemical reaction. Therefore, the number of atoms of each element must be the same on both sides of the equation. In step 2 of the solution, we count the atoms of each element in the reactants and products to determine which elements are imbalanced. This step is crucial because it lays the foundation for balancing the equation accurately. If the number of atoms for each element is the same before and after the reaction, the equation is said to be balanced.

chemical equation balancing

Balancing a chemical equation ensures that the same number of each type of atom is present on both sides of the equation. The process involves adjusting the coefficients, which are the numbers placed before the chemical formulas. The unbalanced equation in this exercise is: Zn + H₂SO₄ → ZnSO₄ + H₂S + H₂O.
First, we balance the atom for one element at a time. Often, it is easiest to start with elements that appear in only one reactant and one product. After making these adjustments, it's essential to check the atom counts again to confirm balance.

• Step 1: Write down the unbalanced equation.
• Step 2: Count the atoms on both sides.
• Step 3: Adjust coefficients to balance each element.
• Step 4: Verify if all elements are balanced.

By following these steps, the equation Zn + 4 H₂SO₄ → ZnSO₄ + H₂S + 4 H₂O is balanced, maintaining the law of conservation of mass.