Question detail
Calculate the number of moles in 50 g 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
Use of amount of substance in relation to masses of pure substances
Question
- A. 2.78 mol
- B. 2.78
- C. 2.50 mol
- D. 3.00 mol
Answer
2.78 mol
Explanation
The relative formula mass of water (H2O) is 18 g/mol. Using the formula moles = mass / Mr, we find that 50 g of water is 50 / 18 = 2.78 mol.
Common mistake
Confusing Mass with Moles
Students often confuse the mass of a substance with the amount in moles, leading to incorrect calculations when converting given masses into moles.
To convert mass to moles, use the formula: moles = mass / relative formula mass. Ensure you calculate the relative formula mass correctly before performing the conversion.
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