Final answer:
The formula for a straight-chain alkane with eight carbon atoms is C8H18. The concept of empirical and molecular formulas is essential in chemistry to represent compounds, with molecular formulas allowing the calculation of molar mass. The Crisscross Method is used for writing ionic compound formulas, which involves crisscrossing ion charges to form subscripts.
Step-by-step explanation:
The formula for forming a straight chain alkane, specifically addressing a student's query about example 9.1.2 writing formulas for an alkane with eight carbon atoms, is based on understanding the basic structural formula of alkanes. Alkanes are hydrocarbons with the general formula CnH2n+2, where 'n' is the number of carbon atoms. For an alkane with eight carbon atoms, the structural formula would be C8H18 because when 'n' equals eight, (2 × 8) + 2 equals 18.
In Chapter 4.5, we go over the concepts of empirical and molecular formulas. An empirical formula represents the simplest whole-number ratio of the elements within a compound, while the molecular formula is the actual number of atoms of each element in a molecule of the compound. The molar mass of a compound can be directly calculated using the molecular formula.
When writing formulas for chemical compounds, such as straight-chain alkanes, the Crisscross Method can be particularly helpful. This method is used for ionic compounds to write the chemical formula by crisscrossing the charges of the ions to become the subscripts of the other ion.
Learning Objectives
Applying these principles, students can correctly write structural formulas for straight-chain alkanes and other types of chemical compounds by understanding their nomenclature and molecular composition.