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CHM 101 CHM 101 Past Questions Objective Question
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Question

Combustion analysis of 0.800 grams of an unknown hydrocarbon yields 2.613 g CO₂ and 0.778 g H₂O. What is the percent composition of the hydrocarbon? [C=12; O=16; H=1;]
Options
A 66.6% C; 33.4% H
B 82.3% C; 17.7% H
C 89.1% C; 10.9% H
Correct Answer
D 92.4% C; 7.60% H
Correct Answer

Option C is the correct answer.

Detailed Explanation

Mass C = (12/44) × 2.613 = 0.7126 g. Mass H = (2/18) × 0.778 = 0.08644 g. %C = (0.7126/0.800)×100 = 89.1%, %H = (0.08644/0.800)×100 = 10.9%.

Hint

All carbon in CO₂ comes from hydrocarbon; all hydrogen in H₂O comes from hydrocarbon.

Question Info

Course: CHM 101
Topic: CHM 101 Past Questions
Type: Objective
Difficulty: Not specified
Question 1082 of 1872
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