Question

Explain why the equivalent weight of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) is half the molar mass of this substance. How many hydrogen ions does each \(\mathrm{H}_{2} \mathrm{SO}_{4}\) molecule produce when reacting with an excess of \(\mathrm{OH}^{-}\) ions?

Short answer

The equivalent weight of H₂SO₄ is half of its molar mass (49 g/mol) because one mole of H₂SO₄ can replace two moles of hydrogen in a chemical reaction. Each H₂SO₄ molecule produces two hydrogen ions when reacting with an excess of OH⁻ ions, as seen in the balanced chemical equation: \(H_2SO_4 + 2 OH^− \rightarrow 2 H_2O + SO_4^{2−}\).

Step-by-step solution

Calculate the molar mass of H₂SO₄

To calculate the molar mass of H₂SO₄, we need to first find the molar mass of each element in the formula and then add them up. The molar mass of hydrogen (H) is 1 g/mol, sulfur (S) is 32 g/mol, and oxygen (O) is 16 g/mol. The formula for H₂SO₄ has two hydrogen atoms, one sulfur atom, and four oxygen atoms. So, the molar mass of H₂SO₄ can be calculated as follows: Molar mass of H₂SO₄ = (2 × 1 g/mol) + (1 × 32 g/mol) + (4 × 16 g/mol) = 2 g/mol + 32 g/mol + 64 g/mol = 98 g/mol

Define equivalent weight and determine the equivalent weight of H₂SO₄

The equivalent weight of a substance is the mass of that substance that reacts with or replaces one mole of hydrogen (1 g/mol) in a chemical reaction. In the case of H₂SO₄, there are two replaceable hydrogen atoms in the molecule (H₂). Therefore, one mole of H₂SO₄ can replace two moles of hydrogen. To find the equivalent weight of H₂SO₄, we simply divide its molar mass by the number of hydrogen atoms that can be replaced. Equivalent weight of H₂SO₄ = (Molar mass of H₂SO₄) / (Number of replaceable hydrogen atoms) = 98 g/mol / 2 = 49 g/mol We can see that the equivalent weight of H₂SO₄ is half of its molar mass.

Determine the number of hydrogen ions produced by each H₂SO₄ molecule

Each molecule of H₂SO₄ contains two hydrogen atoms, which can be released as hydrogen ions (H⁺). When H₂SO₄ reacts with an excess of hydroxide ions (OH⁻), it can act as a strong acid and release both hydrogen ions. The balanced chemical equation for this reaction is: H₂SO₄ + 2 OH⁻ → 2 H₂O + SO₄²⁻ From this equation, we can see that each H₂SO₄ molecule reacts with two OH⁻ ions to produce two molecules of water and one sulfate ion (SO₄²⁻). This means that each H₂SO₄ molecule produces two hydrogen ions (H⁺) when it reacts with an excess of OH⁻ ions. In conclusion, the equivalent weight of H₂SO₄ is half of its molar mass because one mole of H₂SO₄ can replace two moles of hydrogen in a chemical reaction. Each H₂SO₄ molecule produces two hydrogen ions when reacting with an excess of OH⁻ ions.

Key concepts

Molar Mass

In chemistry, molar mass is a crucial concept that helps us understand the quantity of matter in a substance. It is defined as the mass of one mole of a substance and is expressed in grams per mole (g/mol). To calculate the molar mass of a compound, you need to know the atomic masses of all the elements involved and add them up according to their proportions in the compound.
For example, in sulfuric acid (\(\mathrm{H}_{2}\mathrm{SO}_{4}\)), the molar mass of hydrogen (H) is 1 g/mol, sulfur (S) is 32 g/mol, and oxygen (O) is 16 g/mol. This compound consists of two hydrogen atoms, one sulfur atom, and four oxygen atoms. You calculate the molar mass of \(\mathrm{H}_{2}\mathrm{SO}_{4}\) as:

• 2 × 1 (for hydrogen) = 2 g/mol
• 1 × 32 (for sulfur) = 32 g/mol
• 4 × 16 (for oxygen) = 64 g/mol

Summing these up gives the molar mass of \(\mathrm{H}_{2}\mathrm{SO}_{4}\): 98 g/mol.

Hydrogen Ions

Hydrogen ions (\(\mathrm{H}^{+}\)) play a pivotal role in acidity and chemical reactions. They are essentially just protons, as hydrogen in its ionized state loses its single electron. In the context of acids like sulfuric acid (\(\mathrm{H}_{2}\mathrm{SO}_{4}\)), these ions are responsible for the acidic properties.Sulfuric acid is a strong acid, meaning it dissociates completely in water to release hydrogen ions. Each molecule of \(\mathrm{H}_{2}\mathrm{SO}_{4}\) contains two hydrogen atoms. Thus, it can release two hydrogen ions when it reacts, especially in the presence of strong bases like hydroxide ions (\(\mathrm{OH}^{-}\)).
This ionization is crucial because it not only affects the acidity of a solution but also plays a part in numerous industrial processes.

H₂SO₄

Sulfuric acid, represented chemically as \(\mathrm{H}_{2}\mathrm{SO}_{4}\), is one of the most important industrial chemicals. It is a dense, oily liquid, and it is highly corrosive. In the context of chemistry problems, like those concerning equivalent weight, it's important to understand its composition of two hydrogen, one sulfur, and four oxygen atoms.The term 'equivalent weight' comes into play when looking at how much of \(\mathrm{H}_{2}\mathrm{SO}_{4}\) can react to replace or provide one mole of hydrogen ions in a reaction. Given its ability to release two hydrogen ions, its equivalent weight is calculated as half its molar mass, making the equivalent weight 49 g/mol compared to its full molar mass of 98 g/mol.
This simple calculation is key to grasping how \(\mathrm{H}_{2}\mathrm{SO}_{4}\) behaves in reactions, especially acid-base neutralization.

Chemical Reaction

Chemical reactions are processes that transform one or more substances into new products. In the case of \(\mathrm{H}_{2}\mathrm{SO}_{4}\), an important reaction is its interaction with bases such as hydroxide ions (\(\mathrm{OH}^{-}\)). This specific reaction is an example of a neutralization reaction.When sulfuric acid reacts with an excess of hydroxide ions, it releases hydrogen ions, leading to the formation of water and sulfate ions (\(\mathrm{SO}_{4}^{2-}\)). The reaction can be represented as:\[ \mathrm{H}_{2}\mathrm{SO}_{4} + 2\,\mathrm{OH}^{-} \rightarrow 2\,\mathrm{H}_{2}\mathrm{O} + \mathrm{SO}_{4}^{2-}\]Each \(\mathrm{H}_{2}\mathrm{SO}_{4}\) molecule liberates two hydrogen ions, which combine with the \(\mathrm{OH}^{-}\) to form water. This is a typical illustration of how acids and bases interact to neutralize each other and produce water and salts. Understanding these reactions is fundamental for grasping wider chemical concepts and applications.