Problem 74 - Chemistry Matter and Change

Question

A 25.3-g sample of an unknown compound contains 0.8 g of oxygen. What is the percent by mass of oxygen in the compound?

Step-by-Step Solution

Answer

The percent by mass of oxygen in the unknown compound is approximately 3.16%.

Step 1: Identify the given information

We are given: - Mass of the compound = 25.3 g - Mass of oxygen in the compound = 0.8 g

Step 2: Calculate the percentage of oxygen by mass

To find the percent by mass of oxygen in the compound, we will use the formula: Percent by mass of oxygen = \(\frac{\text{mass of oxygen}}{\text{total mass of compound}}\) × 100 Plug in the given values: Percent by mass of oxygen = \(\frac{0.8}{25.3}\) × 100

Step 3: Perform the calculation

Divide 0.8 by 25.3 and multiply by 100: Percent by mass of oxygen = \(\frac{0.8}{25.3}\) × 100 ≈ 3.16% Thus, the percent by mass of oxygen in the unknown compound is approximately 3.16%.

Key Concepts

Mass Percentage Calculation

Mass percentage calculation is a fundamental concept in chemistry that helps us understand the composition of mixtures and compounds. The mass percent of a substance within a compound is a way to express how much of that substance is present when compared to the overall mass of the compound. It's calculated using an easy formula, making it accessible for beginners.To calculate the mass percentage, you simply use the formula:\[ \text{Percent by mass} = \frac{\text{mass of component}}{\text{total mass of compound}} \times 100\]Let's apply this formula to the exercise where we found the mass percent of oxygen in an unknown compound. Here, we know:

• Total mass of the compound = 25.3 g
• Mass of the oxygen = 0.8 g

Substituting these values into the formula gives us:\[ \text{Percent by mass of oxygen} = \frac{0.8}{25.3} \times 100 \approx 3.16\%\]Thus, the oxygen comprises about 3.16% of the unknown compound by mass.

Oxygen Content Calculation

Calculating the oxygen content in a compound is crucial for determining the role of oxygen in various chemical reactions and applications. Having a clear understanding of such components can aid in predicting the compound's behavior and its potential uses.The exercise highlights a simple method to find the oxygen content by mass in an unknown compound, illustrating a common chemical problem. We start by analyzing the provided data:

• The sample contains 0.8 g of oxygen.
• The overall mass of the compound is 25.3 g.

The formula used helps in establishing the relationship between the oxygen present and the overall compound mass, leading to the calculation of its percentage:\[ \text{Percent by mass of oxygen} = \frac{\text{mass of oxygen}}{\text{total mass of compound}} \times 100\]This practical example shows how chemists can determine the significance of a specific element in a complex compound.

Unknown Compound Analysis

Analyzing an unknown compound to determine its composition involves identifying each element's contribution to the total mass. It's a process used frequently by chemists to characterize and understand new substances. By determining the mass percentage, we get a clearer picture of what the compound is made of, which can guide further tests or syntheses. In this exercise, the compound's identity isn't specified, but knowing oxygen composes 3.16% of its mass provides vital clues. Consider some key steps for tackling similar problems:

• Obtain precise measurements of the component and overall mass.
• Use known formulas to calculate the percent by mass or any necessary values.
• Interpret results to infer possible components or reactions.

By understanding the roles of each element, as calculated through percent compositions like the oxygen content here, scientists can propose or verify the nature and potential application of unknown compounds.