Question detail
Calculate the number of moles in 100 grams of water (H₂O).
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. 5.56 mol
- B. 2.78 mol
- C. 3.33 mol
- D. 4.44 mol
Answer
5.56 mol
Explanation
First, calculate the relative molecular mass (Mr) of water: H (1) x 2 + O (16) = 18 g/mol. Using the formula: moles = mass / Mr, we substitute: moles = 100 g / 18 g/mol = 5.56 mol.
Common mistake
Common Mistake in Avogadro Constant Calculations
Students often forget to convert the particle number to moles using the Avogadro constant before performing calculations.
To fix this, remember the formula: n = N / L, where n is the number of moles, N is the number of particles, and L is the Avogadro constant (6.022 x 10^23 mol^-1). For example, if you have 1.2044 x 10^24 particles, substitute: n = 1.2044 x 10^24 / 6.022 x 10^23 = 2.00 moles.
Related flashcards
Flashcard 1 of 5
Related practice questions
Question 1 of 5
Choose an answer, get feedback, then move sideways through the set.