Problem 36 - Chemistry A Molecular Approach

Question

Palladium forms three different compounds with sulfur. The mass of sulfur per gram of palladium in each compound is listed here. Show that these masses are consistent with the law of multiple proportions. $$ \begin{array}{cc} \text { Compound } & \text { Grams } \text { S per Gram Pd } \\ \hline \text { A } & 0.603 \\ \hline \text { B } & 0.301 \\ \hline \text { C } & 0.151 \\ \hline \end{array} $$

Step-by-Step Solution

Answer

The ratios of the mass of sulfur per gram of palladium are 2:1 for both compound A to B and compound B to C, demonstrating consistency with the law of multiple proportions.

Step 1: Understand the Law of Multiple Proportions

The law of multiple proportions states that when two elements (here palladium and sulfur) form more than one compound, the masses of one element that combine with a fixed mass of the other element are in ratios of small whole numbers.

Step 2: Calculate the Ratio of Sulfur Masses in Compounds A and B

First, find the ratio of the mass of sulfur per gram of palladium between compounds A and B. This is done by dividing the mass of sulfur in compound A by the mass in compound B: \( \frac{0.603\, \text{g S}}{0.301\, \text{g S}} = 2 \). This shows a simple whole number ratio.

Step 3: Calculate the Ratio of Sulfur Masses in Compounds B and C

Next, find the ratio of the mass of sulfur per gram of palladium between compounds B and C. Divide the mass of sulfur in compound B by the mass in compound C: \( \frac{0.301\, \text{g S}}{0.151\, \text{g S}} = 2 \). Again, this ratio is a simple whole number.

Step 4: Examine the Ratios

Comparing the mass ratios of sulfur in the compounds, we see that the ratios are 2:1 when comparing A to B and B to C. This indicates that the mass of sulfur per gram of palladium in each compound is consistent with the law of multiple proportions, as the ratios are small whole numbers.

Key Concepts

Chemical Composition

Understanding the chemical composition of substances is essential in the study of chemistry. Chemical composition refers to the arrangement, type, and ratio of atoms that constitute a particular chemical compound. It dictates the properties and behavior of that compound.

When looking at the problem concerning palladium and sulfur compounds, chemical composition provides insight into how the different quantities of sulfur relate to a fixed amount of palladium. This relationship is a clear indicator of the chemical makeup of the distinct compounds formed between sulfur and palladium. By comparing these compositions, we can demonstrate the law of multiple proportions, which relies on the concept that these compositions can be expressed in ratios of small whole numbers.

Stoichiometry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It is essentially the math behind chemical equations, allowing chemists to predict the amounts of substances consumed and produced in a given reaction.

In the case of palladium compounds with sulfur, stoichiometry allows us to calculate the mass ratios and understand the proportions in which these elements combine to form chemical compounds. Through calculations, as presented in the step-by-step solution, you can see the use of stoichiometric principles to confirm that the mass ratios are indeed in small whole numbers, which supports the law of multiple proportions.

Chemical Compounds

Chemical compounds are substances that consist of two or more different types of elements, held together by chemical bonds. Each compound has a unique composition and structure that determines its chemical properties and reactivity.

Palladium and sulfur can combine in different ways to form a variety of compounds, each with a unique chemical composition. As the exercise reveals, palladium forms three different compounds with sulfur, each having a distinct mass of sulfur per gram of palladium. The ability to form multiple compounds with varying elemental ratios is a fundamental characteristic of chemical elements and a perfect illustration of the law of multiple proportions. Understanding the nature of chemical compounds is critical in explaining why these ratios of sulfur to palladium occur in the pattern as exemplified by the problem provided.