Final answer:
The number '3' in '3C4H10' means there are three molecules of butane, not three times more carbon than hydrogen, not three atoms, nor three bonds in the formula.
Step-by-step explanation:
The number "3" in the chemical formula "3C4H10" indicates that there are three molecules of the compound represented by the chemical formula C4H10. This compound is butane, an alkane with four carbon atoms and ten hydrogen atoms. A single molecule of butane has four carbon atoms and ten hydrogen atoms, so the prefix '3' means we have triple that amount—in other words, a total of three molecules of butane.
To understand this concept it's crucial to know that molecular formulas specify the actual number of atoms of each element in a molecule. For example, the molecular formula of methane (CH4) indicates one carbon atom and four hydrogen atoms in a methane molecule. Similarly, C2H6 represents ethane, indicating a molecule composed of two carbon atoms and six hydrogen atoms. Such molecular formulas do not express information about the bonds and shapes of the molecules; that information is conveyed by structural formulas, which might show double or triple bonds, and how atoms are spatially arranged.
If a structural formula shows a triple bond between carbon atoms or a specific arrangement of atoms such as a methyl group (CH3) or an OH group on certain carbon atoms, it is providing detailed information about the bonding and arrangement of the molecule, beyond what is stated in the molecular formula.