Chemistry · Grades 10–12
One-double-bond hydrocarbon
CnH2n applies here to an acyclic hydrocarbon with one double bond. A formula alone does not distinguish an alkene from a cycloalkane.
Rule and assumptions
CnH2n applies here to an acyclic hydrocarbon with one double bond. A formula alone does not distinguish an alkene from a cycloalkane.
CₙH₂ₙ
Worked examples
An acyclic hydrocarbon has 13 carbon atoms, exactly one C=C bond and no other multiple bonds. How many hydrogen atoms are in its formula? Round to 3 decimal places if needed.
CₙH₂ₙ 2 × 13 = 26
26
An acyclic hydrocarbon has 8 carbon atoms, exactly one C=C bond and no other multiple bonds. How many hydrogen atoms are in its formula? Round to 3 decimal places if needed.
CₙH₂ₙ 2 × 8 = 16
16
Try two questions
An acyclic hydrocarbon has 5 carbon atoms, exactly one C=C bond and no other multiple bonds. How many hydrogen atoms are in its formula? Round to 3 decimal places if needed.
An acyclic hydrocarbon has 8 carbon atoms, exactly one C=C bond and no other multiple bonds. How many hydrogen atoms are in its formula? Round to 3 decimal places if needed.
Answers and reasoning
Answers and marking notes
- 10
CₙH₂ₙ 2 × 5 = 10
- 16
CₙH₂ₙ 2 × 8 = 16
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Learning preview · independent educational and translation review required. Suggested grades are not official curriculum alignment.