Question detail
A sample of sodium chloride (NaCl) has a mass of 58.5 g. Calculate the number of moles of sodium chloride in the sample.
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
A sample of sodium chloride (NaCl) has a mass of 58.5 g. Calculate the number of moles of sodium chloride in the sample.
Answer
Chemical amount is measured in moles. A mole is used to count a very large number of particles, atoms, molecules, or ions in a practical way, so calculations can link particle amounts to masses in grams and balanced equations.
Explanation
This answer earns credit because it names the unit, mole, and explains why it is used in quantitative chemistry. It keeps the idea separate from mass: grams measure mass, while moles measure amount of substance. In exam marking, the important steps are to identify the correct relationship, substitute or interpret the values carefully, keep units consistent, and avoid mixing this calculation with neighbouring Unit 4.3 methods.
Common mistake
Confusing moles with mass
Students often confuse the concept of moles with mass, thinking that mass is the same as the amount of substance.
Remember that moles measure the amount of substance, while mass is measured in grams. Use the relationship between mass and moles to clarify this distinction.
Related flashcards
Flashcard 1 of 5
Related practice questions
Question 1 of 5
Choose an answer, get feedback, then move sideways through the set.