Question Detail
Question
An unknown compound X with a molecular weight of 90 g/mol was found to contain the following: carbon - 40% and hydrogen - 6.67%. If oxygen is the only other component, find the molecular formula of X?
Correct Answer
Option C is the correct answer.
Detailed Explanation
Oxygen % = 100% - 40% - 6.67% = 53.33%. Assume 100 g: moles C = 40/12 = 3.33, H = 6.67/1 = 6.67, O = 53.33/16 = 3.33. Ratio C:H:O = 1:2:1, so empirical formula = CH₂O (mass 30). n = 90/30 = 3, so molecular formula = C₃H₆O₃.
Hint
Find the empirical formula first, then divide the given molecular weight by the empirical formula weight.