Question

In a series of experiments, a chemist prepared three different compounds that contain only iodine and fluorine and determined the mass of each element in each compound: \begin{tabular}{ccc} \hline Compound & Mass of Iodine (g) & Mass of Fluorine (g) \\ \hline 1 & \(4.75\) & \(3.56\) \\ 2 & \(7.64\) & \(3.43\) \\ 3 & \(9.41\) & \(9.86\) \\ \hline \end{tabular} (a) Calculate the mass of fluorine per gram of iodine in each compound. (b) How do the numbers in part (a) support the atomic theory?

Short answer

The mass of fluorine per gram of iodine for each compound is: Compound 1: \(0.7495\,\text{g F/g I}\) Compound 2: \(0.4489\,\text{g F/g I}\) Compound 3: \(1.0478\,\text{g F/g I}\) These values indicate that the elements combine in whole-number ratios to form compounds: Compound 1 has a mass ratio of \(5/3\) that of Compound 2, and Compound 3 has a mass ratio of \(7/3\) that of Compound 2. This observation supports the atomic theory.

Step-by-step solution

Calculate the mass of fluorine per gram of iodine in each compound

To calculate the mass of fluorine per gram of iodine in each compound, we will divide the mass of fluorine by the mass of iodine for each compound: Compound 1: \(\frac{3.56\,\text{g}}{4.75\,\text{g}} = 0.7495\,\text{g F/g I}\) Compound 2: \(\frac{3.43\,\text{g}}{7.64\,\text{g}} = 0.4489\,\text{g F/g I}\) Compound 3: \(\frac{9.86\,\text{g}}{9.41\,\text{g}} = 1.0478\,\text{g F/g I}\)

Analyze how the calculated numbers support the atomic theory

Now we need to analyze how the calculated mass of fluorine per gram of iodine supports atomic theory. The atomic theory states that elements combine in whole-number ratios to form compounds. Let's see if the mass ratios we calculated are in a whole-number ratio. To do this, we need to find the ratio of the mass ratios: Compound 1: \(\frac{0.7495}{0.4489} = 1.669\), which is approximately \(5/3\) Compound 2: \(\frac{1.0478}{0.4489} = 2.330\), which is approximately \(7/3\) The mass ratio of compound 1 is approximately \(5/3\) that of compound 2, and the mass ratio of compound 3 is approximately \(7/3\) that of compound 2. These ratios can also be expressed as whole numbers: Compound 1: \(5\) Compound 2: \(3\) Compound 3: \(7\) The fact that the mass ratios of the three compounds are in whole-number ratios supports the atomic theory, which states that elements combine in whole-number ratios to form compounds.

Key concepts

Mass Ratio Calculation

Understanding the mass ratio calculation is essential in chemistry, particularly when studying the composition of chemical compounds. When a chemist works on combining elements to form compounds, they often measure the amounts of each element in grams. However, for a clearer understanding, these masses are then compared to one another to compute ratios.

In the case of the compounds formed with iodine and fluorine, the mass ratio is found by dividing the mass of fluorine by the mass of iodine for each compound. This calculation informs us about the proportions in which each element is present in the compound. For example, in Compound 1, with a calculated ratio of approximately 0.7495 g of fluorine for every gram of iodine, we see a specific relationship between the fluorine and iodine that makes up the chemical substance.

These ratios often reveal a deeper pattern concerning the fixed proportions of elements in compounds, shedding light on empirical formulas and the fundamental law of definite proportions, which indicates that a chemical compound always contains exactly the same proportion of elements by mass.

Fluorine and Iodine Compounds

Compounds with fluorine and iodine are examples of binary compounds, composed of two different chemical elements. Fluorine, being the most electronegative element, typically forms compounds by gaining electrons and becoming a negatively charged ion, known as a fluoride. Iodine, which is less electronegative, can form positive iodide ions but in compounds with fluorine, it is usually the less electronegative component.

When combined, these two elements create distinct compounds with varying ratios of iodine to fluorine. The compounds are diverse, and they illustrate how the varying amounts of each element give rise to different substances with unique properties. In the exercise, we observed three different compounds exhibiting different iodine to fluorine mass ratios, signaling that multiple, distinct chemical entities have been created. It's the precise measurement and calculation of these compounds that aids in the identification and categorization of such chemical entities.

Chemical Compound Composition

The chemical compound composition is a foundational concept which describes the makeup of a chemical substance in terms of the elements present and their relative proportions. In simple terms, it's about what is in a compound and how much of each element is there. This information is fundamental to chemists, who use it to predict how a compound will behave, its reactivity, and its properties.

The atomic theory forms a basis for understanding chemical compound compositions, proposing that compounds are combinations of atoms in fixed, integer-number ratios. This is observed in the three compounds containing iodine and fluorine. Each has a unique composition, indicated by the different mass ratios of iodine to fluorine. These mass ratios are related to the molecular formulas of the compounds, reflecting the atom-to-atom ratios of the elements within them.

The experiment's concluding observation – that the mass ratios are in whole-number multiples of each other – supports the principles of atomic theory and reinforces our comprehension of how elements combine to form compounds with distinct and consistent compositions.