Problem 97 - Chemistry Matter and Change

Question

Identify Lead Compounds A sample of a certain lead compound contains 6.46 g of lead for each gram of oxygen. A second sample has a mass of 68.54 g and contains 28.76 g of oxygen. Are the two samples the same? Explain.

Step-by-Step Solution

Answer

The two samples are not the same compound because their ratios of mass of lead to mass of oxygen are different. The ratio of the first sample is 6.46, while the ratio of the second sample is 1.38 (calculated by dividing 39.78 g of lead by 28.76 g of oxygen).

Step 1: Determine the mass of lead in the second sample

To find the mass of lead in the second sample, subtract the mass of oxygen from the total mass: Mass of lead = Total mass - Mass of oxygen Mass of lead = 68.54 g - 28.76 g

Step 2: Calculate the mass of lead in the second sample

Subtract the mass of oxygen from the total mass to find the mass of lead in the second sample: Mass of lead = 68.54 g - 28.76 g = 39.78 g

Step 3: Calculate the ratio of the mass of lead to the mass of oxygen in the second sample

Divide the mass of lead by the mass of oxygen to find the ratio in the second sample: Ratio (second sample) = Mass of lead / Mass of oxygen Ratio (second sample) = 39.78 g / 28.76 g

Step 4: Compare the two ratios

If the ratio of lead to oxygen in both samples is the same, they are the same compound. Compare the two ratios: Ratio (first sample) = 6.46 Ratio (second sample) = 39.78 g / 28.76 g = 1.38 Since the ratios are different (6.46 ≠ 1.38), the two samples are not the same compound.

Key Concepts

Chemical Compounds

Chemical compounds are substances formed when two or more elements chemically bond together. Each compound has unique properties and a specific composition. The elements in a compound are always present in a fixed ratio by mass, which is crucial for identifying the compound.

When identifying a compound, it's important to look at the elements' ratios. For example, in a lead compound, we should see how many parts of lead are bonded with oxygen. This fixed ratio distinguishes different compounds.

• A compound is made up of elements combined in a specific ratio.
• This ratio dictates the compound's properties and behavior.
• Changing the ratio results in a different compound.

So, understanding these ratios is vital when working with chemical compounds.

Mass Ratio

The mass ratio in a chemical compound is the ratio of the mass of one element to the mass of another element within the compound. It provides a clear method to determine the identity of a compound by illustrating the proportion of each element present.

When analyzing the identity of an unknown compound, calculating the mass ratio of its components can be informative. For instance, in the exercise example, calculating the ratio of lead to oxygen helps in determining if two samples are the same compound. If two samples have the same mass ratio, they might be the same compound. But if the ratios differ, the compounds are different.

• Accurate calculation of mass ratios can confirm the identity of chemical compounds.
• Different compounds will have different mass ratios despite having the same elements.

The mass ratio is a fundamental insight into the chemical makeup and helps chemists ascertain purity and identity.

Lead Compounds

Lead compounds consist of lead and other elements that form through chemical bonding. These compounds have various applications and occur naturally in different forms. Common lead compounds include lead oxide, lead sulfide, and lead carbonate.

When examining lead compounds, knowing their mass ratios and the other components they pair with is crucial. Like in the provided exercise, if you have two samples, discovering their mass ratios can help you determine whether they are the same or different lead compounds.

• Lead compounds can have different chemical structures and properties.
• The compounds are used in a variety of industrial and scientific applications.
• Identifying the correct lead compound requires precise ratio measurements and calculations.

Understanding lead compounds, their properties, and how to identify them by mass ratio is essential in chemistry.