Question

An analysis revealed that \(5.67 \mathrm{~g}\) of a compound of nitrogen and oxygen contained \(1.47 \mathrm{~g}\) of nitrogen. What are the percentages by mass of nitrogen and oxygen in this compound?

Short answer

The percentages by mass are 25.93% for nitrogen and 74.07% for oxygen in the compound.

Step-by-step solution

Identify the Mass of Each Element

From the problem, we identify that the compound is composed of nitrogen and oxygen. The total mass of the compound is 5.67 g and it contains 1.47 g of nitrogen.

Calculate the Mass of Oxygen

To find the mass of oxygen, subtract the mass of nitrogen from the total mass of the compound: mass of oxygen = total mass of compound - mass of nitrogen.

Calculate the Percentage by Mass of Nitrogen

Use the formula for percentage by mass: \( \text{percentage by mass of an element} = \frac{\text{mass of the element}}{\text{total mass of the compound}} \times 100\% \). Calculate the percentage by mass of nitrogen using its mass and the total mass of the compound.

Calculate the Percentage by Mass of Oxygen

Similarly, calculate the percentage by mass of oxygen using the mass of oxygen found in step 2 and the total mass of the compound.

Write Down the Final Percentages

Present the calculated percentages of nitrogen and oxygen in the compound as the final answer.

Key concepts

Stoichiometry

Stoichiometry is a section of chemistry that involves determining the quantities of reactants and products in chemical reactions. It's akin to a recipe for a chemical transformation where the ingredients (reactants) are transformed into a dish (products) in specific proportions.

In the exercise, stoichiometry is used to delve into the makeup of a compound, determining how much of each element—nitrogen and oxygen—is present by mass. While the exercise didn't require balancing chemical equations, it did invoke a stoichiometric principle: the conservation of mass. This principle states that in an isolated system, mass is neither created nor destroyed. So, the sum of the masses of the reactants (the nitrogen and oxygen in the compound) must be equal to the total mass of the compound.

Overall, grasping stoichiometry is fundamental for anyone studying chemistry as it bridges the gap between the molecular scale and the real-world scale, enabling chemists to predict the amounts of substances consumed and produced in a given reaction.

Chemical Composition

Chemical composition refers to the identity and proportion of the elements that make up a chemical compound. Understanding a compound's chemical composition is crucial because it defines the compound's physical and chemical properties.

In our exercise, by determining the mass of nitrogen and subsequently finding the mass of oxygen, we are breaking down the compound into its constituents. This analysis tells us exactly what's in the compound and in what amounts, fulfilling the 'recipe' that describes the compound's chemical makeup.

• The mass of nitrogen is given as 1.47 g.
• The oxygen mass is deduced by subtraction from the total mass.

The result of this analysis can be expressed in percentages, indicating the fraction of each element in the compound. This percentage composition by mass is a common way to present chemical compositions, as it is independent of the sample size and hence useful for comparing different substances.

Mass-to-Mass Conversion

Mass-to-mass conversion is a stoichiometric technique used to calculate the mass of one substance in a reaction based on the mass of another substance. It relies on the fixed ratios dictated by the balanced chemical equation of the reaction.

In the context of the textbook exercise, we are not dealing with a reaction, but with the mass-to-mass conversion principle which is still applicable. We are essentially converting the known mass of nitrogen to the unknown mass of oxygen within a compound. Here's a simplified outline:

• Find the mass of oxygen by subtracting the mass of nitrogen from the total compound mass.
• Convert these masses to percentages to understand their ratio in the compound.

The result gives insight into the relative amounts of each element, showcasing how mass-to-mass conversion can be applied outside of stoichiometric calculations to understand the composition of a compound.