Question detail
Calculate the relative molecular mass of sulfuric acid (H2SO4).
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Amount of substance
Question
- A. 98
- B. 96
- C. 100
- D. 94
Answer
98
Explanation
The relative molecular mass of sulfuric acid is calculated using the formula: Mr = sum(Ar of all atoms in the formula). For H2SO4, Ar of H is 1, S is 32, and O is 16. Therefore, Mr = (2 * 1) + (1 * 32) + (4 * 16) = 2 + 32 + 64 = 98.
Common mistake
Confusing Relative Molecular Mass with Atomic Mass
Students often confuse relative molecular mass (Mr) with relative atomic mass (Ar), leading to incorrect calculations when determining the mass of a compound.
To fix this, remember that relative molecular mass (Mr) is the sum of the relative atomic masses of all atoms in a molecule. For example, for water (H2O), calculate Mr as follows: Mr = (2 × Ar of H) + (1 × Ar of O) = (2 × 1) + (16) = 18. Therefore, the relative molecular mass of water is 18 g/mol.
Related flashcards
Flashcard 1 of 5
Related practice questions
Question 1 of 5
Choose an answer, get feedback, then move sideways through the set.