In a combustion analysis, \(3.21 \mathrm{~g}\) of a hydrocarbon formed \(4.48 \mathrm{~g}\) of water and \(9.72 \mathrm{~g}\) of carbon dioxide. Deduce its empirical formula and state whether it is likely to be an alkane, an alkene, or an alkyne. Explain your reasoning.

The empirical formula of a compound represents the simplest whole-number ratio of the atoms of each element in the compound. It's the building block for understanding the composition of a molecule. In a combustion analysis, the empirical formula is deduced by first determining the amount of carbon (C) and hydrogen (H) present in the original hydrocarbon. This process involves using the molar masses of water (H2O) and carbon dioxide (CO2) to calculate the moles of each element.

For example, a given amount of H2O produced after combustion will reveal the amount of hydrogen in the hydrocarbon. As water contains two hydrogen atoms per molecule, the moles of hydrogen are twice the moles of water produced. Similarly, since CO2 contains one carbon atom per molecule, the moles of carbon in the hydrocarbon correspond to the moles of CO2 produced. Once the moles of carbon and hydrogen are known, they can be divided by the smallest value to find the mole ratio and ultimately, the empirical formula.

The mole ratio is a critical concept that compares the number of moles of one substance to the number of moles of another. After a combustion analysis, once the moles of hydrogen and carbon are calculated, they are compared to each other to find the mole ratio. This ratio helps in determining the empirical formula of the hydrocarbon.

To find the ratio, divide the moles of each element by the smallest number of moles present. This typically yields a whole number or a simple fraction. If the ratio isn't a whole number, it will be necessary to multiply the ratios by the smallest integer that produces whole numbers for both elements. These whole numbers then become the subscripts in the empirical formula.

The study of hydrocarbons is immensely important in organic chemistry and fuels analysis. Hydrocarbons are compounds composed solely of carbon and hydrogen. They are categorized into three primary types: alkanes, alkenes, and alkynes.

• Alkanes have single bonds between carbon atoms and follow the general formula CnH2n+2.
• Alkenes contain at least one double bond between carbon atoms, with the formula CnH2n.
• Alkynes include at least one triple bond and follow the formula CnH2n-2.

The hydrocarbon type can be deduced from the empirical formula by comparing the amount of hydrogen relative to carbon found from the mole ratio. If the ratio fits one of the specific formulas above, you can determine whether the hydrocarbon is an alkane, alkene, or alkyne.

For instance, if the empirical formula derived has a C to H ratio that fits the general formula of CnH2n+2, the compound is likely an alkane. This type of analysis is fundamental to understanding the behavior of different hydrocarbons in chemical reactions and their applications in real-world contexts.