Question detail
Calculate the number of moles in 50 grams of water (H2O). The relative formula mass (Mr) of water is 18 g/mol.
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Use of amount of substance in relation to masses of pure substances
Question
- A. 2.78 mol
- B. 2.50 mol
- C. 3.00 mol
- D. 1.67 mol
Answer
2.78 mol
Explanation
The number of moles is calculated using the formula moles = mass / Mr. Here, moles = 50 g / 18 g/mol = 2.78 mol.
Common mistake
Confusing Mole Concept
Students often think that one mole of different substances contains different numbers of particles.
Emphasize that one mole of any substance, regardless of its type, contains the same number of particles, which is defined by the Avogadro constant (6.02 x 10^23).
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