Question

Write the formula for (a) an alkene with two carbon atoms. (b) an alkane with 22 hydrogen atoms. (c) an alkyne with three carbon atoms.

Short answer

Answer: (a) The alkene with two carbon atoms is ethene, with the chemical formula C₂H₄. (b) The alkane with 22 hydrogen atoms is decane, with the chemical formula C₁₀H₂₂. (c) The alkyne with three carbon atoms is propyne, with the chemical formula C₃H₄.

Step-by-step solution

(a) Alkene with two carbon atoms

To find the formula for an alkene with two carbon atoms, we can use the general formula for alkenes CₙH₂ₙ. Replace n with the number of carbon atoms (2), and we get: C₂H₂ * 2 = C₂H₄ Therefore, the alkene with two carbon atoms is ethene, whose formula is C₂H₄.

(b) Alkane with 22 hydrogen atoms

To find the formula for an alkane with 22 hydrogen atoms, we can use the general formula for alkanes CₙH₂ₙ₊₂. We need to find a value for n that satisfies 2ₙ + 2 = 22, which is: 2ₙ = 22 - 2 = 20 n = 20 / 2 = 10 So, the alkane with 22 hydrogen atoms has 10 carbon atoms. The formula of the alkane is C₁₀H₂₂. The corresponding alkane is decane.

(c) Alkyne with three carbon atoms

To find the formula for an alkyne with three carbon atoms, we can use the general formula for alkynes CₙH₂ₙ₋₂. Replace n with the number of carbon atoms (3), and we get: C₃H₂ * 3 - 2 = C₃H₂ C₃H₄ Therefore, the alkyne with three carbon atoms is propyne, whose formula is C₃H₄.