Chapter 9: Problem 31
What is the mass percent of each element in hydrogen peroxide, \(\mathrm{H}_{2} \mathrm{O}_{2} ?\)
Short Answer
Expert verified
In hydrogen peroxide (\(\mathrm{H}_{2}\mathrm{O}_{2}\)), the mass percent of hydrogen is approximately 5.88% and the mass percent of oxygen is approximately 94.12%.
Step by step solution
01
Find the molar mass of hydrogen peroxide
The molecular formula of hydrogen peroxide is \(\mathrm{H}_{2}\mathrm{O}_{2}\). To find the molar mass, we need to add up the molar masses of all the elements in the molecule. The molar masses of hydrogen (H) and oxygen (O) are respectively 1 g/mol and 16 g/mol. So, the molar mass of hydrogen peroxide is:
Molar mass of \(\mathrm{H}_{2}\mathrm{O}_{2} = 2 \times 1 + 2 \times 16 = 34\,\text{g/mol}\).
02
Calculate the mass percent of hydrogen
Now that we have the molar mass of hydrogen peroxide, we can determine the mass percent of hydrogen (H). The mass of 2 moles of hydrogen in the molecule is:
Mass of hydrogen = 2 × 1 = 2 g
Next, we'll calculate the mass percentage of hydrogen:
Mass percent of hydrogen = \(\frac{\text{mass of hydrogen}}{\text{molar mass of }\mathrm{H}_{2}\mathrm{O}_{2}}\) × 100%
= \(\frac{2}{34}\times100\% \approx 5.88\%\)
03
Calculate the mass percent of oxygen
Next, we calculate the mass percent of oxygen (O). The mass of 2 moles of oxygen in the molecule is:
Mass of oxygen = 2 × 16 = 32 g
Now, determine the mass percentage of oxygen:
Mass percent of oxygen = \(\frac{\text{mass of oxygen}}{\text{molar mass of }\mathrm{H}_{2}\mathrm{O}_{2}}\) × 100%
= \(\frac{32}{34}\times100\% \approx 94.12\%\)
So, the mass percent of hydrogen and oxygen in hydrogen peroxide (\(\mathrm{H}_{2}\mathrm{O}_{2}\)) are approximately 5.88% and 94.12%, respectively.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding Molar Mass
Molar mass is a fundamental concept in chemistry that relates to the mass of one mole of a substance. Simply put, it tells us how much one mole of that substance weighs, in grams per mole (g/mol). To determine molar mass, you need to know the atomic weights of the elements involved.
- The periodic table provides the atomic weights: hydrogen (H) is approximately 1 g/mol, and oxygen (O) is about 16 g/mol.
- For compounds, molar mass is the sum of the atomic masses of all atoms present in a molecule.
Exploring Hydrogen Peroxide
Hydrogen peroxide is a simple compound with a chemical formula of \(\mathrm{H}_{2}\mathrm{O}_{2}\). It's well-known for its antiseptic properties and is commonly used for cleaning wounds.
- This compound consists of two hydrogen atoms and two oxygen atoms.
- It's a pale blue liquid in its pure form, but often appears colorless.
- It's readily miscible with water due to its similar hydrogen bonding capacity.
Introduction to Elemental Analysis
Elemental analysis is a crucial technique in chemistry, allowing us to determine the elemental composition of a compound. It's the quantitative breakdown of a compound's constituents. Through this process, we identify the proportion of each element by mass.
- The analysis often uses techniques like mass spectrometry or combustion analysis.
- Mass percent composition, as calculated here, provides insight into the distribution of elements within a compound.
Chemical Formulas Explained
Chemical formulas are symbolic representations of the elements in a compound and show the ratio of these elements. They serve as a fundamental tool for chemists to convey information concisely.
- Subscripts in a chemical formula denote the number of atoms of each element in a molecule.
- For example, \(\mathrm{H}_{2}\mathrm{O}_{2}\) indicates two hydrogen atoms and two oxygen atoms per molecule.
- These formulas are instrumental in chemical equations, stoichiometry, and understanding reactions.