Chapter 2: Problem 68
A sample of ethanol (ethyl alcohol), \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH},\) contains \(4.2 \times 10^{23}\) hydrogen atoms. How many \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\) molecules are in this sample?
Short Answer
Expert verified
There are \(7 \times 10^{22}\) \(\mathrm{C}_{2}\mathrm{H}_{5}\mathrm{OH}\) molecules.
Step by step solution
01
Understanding the problem
We need to determine how many molecules of ethanol, \(\mathrm{C}_{2}\mathrm{H}_{5}\mathrm{OH}\), contain \(4.2 \times 10^{23}\) hydrogen atoms. Ethanol has the chemical formula \(\mathrm{C}_{2}\mathrm{H}_{5}\mathrm{OH}\), which means each molecule of ethanol contains 6 hydrogen atoms.
02
Calculate the number of hydrogen atoms per ethanol molecule
Each ethanol molecule \(\mathrm{C}_{2}\mathrm{H}_{5}\mathrm{OH}\) consists of 6 hydrogen atoms due to its structure: \(\mathrm{H}_{5}\) from the ethyl group and an additional \(\mathrm{OH}\) group. Thus, each ethanol molecule has a total of 6 hydrogen atoms.
03
Set up the relationship for molecules to hydrogen atoms
Since one ethanol molecule contains 6 hydrogen atoms, the number of ethanol molecules is the total number of hydrogen atoms divided by 6.
04
Perform the calculation
To find the number of \(\mathrm{C}_{2}\mathrm{H}_{5}\mathrm{OH}\) molecules, divide the total hydrogen atoms \(4.2 \times 10^{23}\) by the number of hydrogen atoms per molecule, which is 6:\[\frac{4.2 \times 10^{23}}{6} = 0.7 \times 10^{23} = 7 \times 10^{22}\]Thus, there are \(7 \times 10^{22}\) ethanol molecules.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding the Chemical Formula
A chemical formula is a notation used to express the types and numbers of atoms in a molecule. For ethanol, the chemical formula is written as \(\mathrm{C}_{2}\mathrm{H}_{5}\mathrm{OH}\). This formula tells us several key things about the ethanol molecule:
- The \(\mathrm{C}_{2}\) indicates that there are two carbon atoms.
- The \(\mathrm{H}_{5}\) shows that there are five hydrogen atoms attached to the carbon chain.
- The \(\mathrm{OH}\) group adds an additional hydrogen and an oxygen atom, totaling six hydrogen atoms in one ethanol molecule.
Exploring Molecules
Molecules are a group of atoms bonded together, representing the smallest identifiable unit of a chemical compound that can take part in a chemical reaction. Ethanol is one such molecule, made up of carbon, hydrogen, and oxygen atoms.
A single molecule of ethanol consists of:
A single molecule of ethanol consists of:
- 2 Carbon atoms (\(\mathrm{C}_{2}\))
- 6 Hydrogen atoms (\(\mathrm{H}_{6}\))
- 1 Oxygen atom (\(\mathrm{O}\))
Role of Hydrogen Atoms
Hydrogen atoms are the simplest type of atom, consisting of just one proton and one electron. In our example of ethanol, hydrogen plays a crucial role due to its presence in significant numbers relative to other atoms.
Since an ethanol molecule, \(\mathrm{C}_{2}\mathrm{H}_{5}\mathrm{OH}\), contains 6 hydrogen atoms, calculating the total number of ethanol molecules in a sample directly involves understanding this composition:
Since an ethanol molecule, \(\mathrm{C}_{2}\mathrm{H}_{5}\mathrm{OH}\), contains 6 hydrogen atoms, calculating the total number of ethanol molecules in a sample directly involves understanding this composition:
- If you know the total hydrogen atoms in a sample, you can determine the number of ethanol molecules by dividing the hydrogen count by 6.
- This relationship is fundamental in stoichiometry, involving the balancing and calculation of atoms in a chemical reaction.
The Ethanol Compound
Ethanol, often recognized as the active ingredient in alcoholic beverages, has a wide range of applications beyond consumption. Chemically, it is an organic compound that belongs to the alcohol group.
The characteristics of ethanol include:
The characteristics of ethanol include:
- A colorless volatile liquid at room temperature.
- Flammable, with a characteristic pleasant odor.
- Used as a solvent in the manufacture of varnishes and perfumes.
- A fuel or fuel additive due to its ability to combust.