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
Question
Type
exam_style
Style
Topic
Use of amount of substance in relation to masses of pure substances
Question
Calculate the number of moles in 50 grams of water (H2O). The relative formula mass (Mr) of water is 18 g/mol.
Answer
2.78 mol
Explanation
This question tests the ability to calculate moles from mass using the formula moles = mass / Mr. The correct application of the formula leads to the correct number of moles.
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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