Question detail
Calculate the percentage by mass of oxygen in the compound C3H8O. Use the relative atomic masses: C = 12, H = 1, O = 16.
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations
Question
Calculate the percentage by mass of oxygen in the compound C3H8O. Use the relative atomic masses: C = 12, H = 1, O = 16.
Answer
The answer is 32.4 %.
Explanation
This uses Percentage Composition because the objective is about interpret subscripts in a formula when calculating relative formula mass. The reasoning belongs to Relative formula mass within Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations, so it should not be confused with nearby quantitative ideas such as mass, moles, concentration, yield, atom economy, or gas volume unless those are named in the objective. Use the focus term formula to keep the answer aligned with AQA GCSE Chemistry 8462 Unit 4.3.
Common mistake
Misinterpreting Subscripts
Students often confuse subscripts in a chemical formula, leading to incorrect calculations of relative formula mass.
Carefully count the number of atoms represented by the subscripts for each element in the formula before calculating the relative formula mass.
Related flashcards
Flashcard 1 of 5
Related practice questions
Question 1 of 5
Choose an answer, get feedback, then move sideways through the set.