(c) Can combustion analysis be used to determine the empirical formula of a compound containing carbon, hydrogen, oxygen, and chlorine?

Verified step by step guidance

1. Step 1: Understand the concept of combustion analysis. Combustion analysis is a method used to determine the elemental composition of a substance. In this process, a sample is burned in excess oxygen to produce carbon dioxide, water, and other products.
2. Step 2: Identify the elements that can be determined by combustion analysis. Combustion analysis can directly determine the amount of carbon and hydrogen in a compound because these elements are converted to carbon dioxide and water, respectively, which can be collected and measured.
3. Step 3: Consider the elements that cannot be directly determined by combustion analysis. Oxygen and chlorine are not directly determined by this method because they do not form unique gases that can be easily collected and measured. However, their presence can be inferred indirectly.
4. Step 4: Calculate the amount of oxygen and chlorine. After determining the amounts of carbon and hydrogen, the remainder of the sample's mass is attributed to the other elements present, in this case, oxygen and chlorine.
5. Step 5: Determine the empirical formula. Once the amounts of carbon, hydrogen, oxygen, and chlorine are known, these can be converted to moles and the empirical formula can be determined by finding the simplest whole number ratio of these elements.

Key Concepts

Combustion Analysis

Combustion analysis is a technique used to determine the elemental composition of organic compounds. In this method, a sample is burned in excess oxygen, converting its elements into gaseous products, primarily CO2 and H2O. By measuring the amounts of these products, one can calculate the moles of carbon and hydrogen in the original compound, which is essential for determining its empirical formula.

Empirical Formula

The empirical formula of a compound represents the simplest whole-number ratio of the elements present in that compound. It is derived from the mole ratios obtained from combustion analysis or other methods. For compounds containing multiple elements, such as carbon, hydrogen, oxygen, and chlorine, the empirical formula provides a foundational understanding of the compound's composition, even if it does not reflect the actual molecular structure.

Elemental Analysis of Chlorine

In combustion analysis, while carbon, hydrogen, and oxygen can be quantified through the measurement of CO2 and H2O, chlorine presents a challenge. Chlorine does not form stable gaseous products during combustion; instead, it typically forms HCl. Therefore, additional analytical techniques, such as titration or ion chromatography, are often required to accurately determine the chlorine content in the compound, which is crucial for calculating the complete empirical formula.