Question

The molecular mass of \(\text{H}_2\text{SO}_4\) acid is :

• A. 98
• B. 100
• C. 49
• D. 97

Hint:

To calculate molecular mass of \(\text{H}_2\text{SO}_4\): 1. List atoms and their counts: H (2), S (1), O (4). 2. Use approximate atomic masses: H=1, S=32, O=16. 3. Calculate total mass: \((2 \times \text{mass of H}) + (1 \times \text{mass of S}) + (4 \times \text{mass of O})\) \(= (2 \times 1) + (1 \times 32) + (4 \times 16)\) \(= 2 + 32 + 64\) \(= 98\). The unit can be amu (atomic mass units) for molecular mass or g/mol for molar mass.

Answer 1

The Correct Option is A

Concept: The molecular mass (or molar mass) of a compound is the sum of the atomic masses of all the atoms present in one molecule of that compound. Atomic masses are typically given in atomic mass units (amu) or grams per mole (g/mol). Step 1: Identify the atoms and their counts in one molecule of \(\text{H}_2\text{SO}_4\) (Sulfuric Acid) One molecule of \(\text{H}_2\text{SO}_4\) contains:
2 atoms of Hydrogen (H)
1 atom of Sulfur (S)
4 atoms of Oxygen (O) Step 2: List the approximate atomic masses of these elements (Commonly used approximate atomic masses):
Atomic mass of Hydrogen (H) \(\approx 1 \text{ amu (or g/mol)}\)
Atomic mass of Sulfur (S) \(\approx 32 \text{ amu (or g/mol)}\)
Atomic mass of Oxygen (O) \(\approx 16 \text{ amu (or g/mol)}\) Step 3: Calculate the total mass contributed by each element
Mass from Hydrogen: \(2 \text{ atoms} \times 1 \text{ amu/atom} = 2 \text{ amu}\)
Mass from Sulfur: \(1 \text{ atom} \times 32 \text{ amu/atom} = 32 \text{ amu}\)
Mass from Oxygen: \(4 \text{ atoms} \times 16 \text{ amu/atom} = 64 \text{ amu}\) The handwritten calculation \(1\times2 + 32 + 16\times4\) on the image reflects this step. Step 4: Sum these masses to get the molecular mass of \(\text{H}_2\text{SO}_4\) Molecular mass of \(\text{H}_2\text{SO}_4\) = (Mass from H) + (Mass from S) + (Mass from O) Molecular mass of \(\text{H}_2\text{SO}_4\) = \(2 + 32 + 64\) Molecular mass of \(\text{H}_2\text{SO}_4\) = \(34 + 64\) Molecular mass of \(\text{H}_2\text{SO}_4\) = \(98 \text{ amu (or g/mol)}\) The molecular mass of \(\text{H}_2\text{SO}_4\) acid is 98. This matches option (1).