You calculate the number of hydrogen atoms by analyzing the chemical formula of a molecule and using stoichiometric principles.
Understanding the Process
The key to calculating hydrogen atoms lies in understanding the chemical formula of the compound in question. Each subscript in a formula indicates how many of that particular atom is present in a single molecule.
Step-by-Step Calculation
- Identify the Chemical Formula: First, you need the precise chemical formula of the molecule you’re analyzing.
- Locate Hydrogen Atoms: Pinpoint the symbol 'H' within the formula.
- Note the Subscript: The number following the 'H' is the number of hydrogen atoms in each molecule. If no number is present, it is understood to be '1'.
- If there are parentheses : When hydrogen is inside a parenthesis, you must multiply the subscript on the outside of the parenthesis to the number of H atoms inside.
- Calculate the Total: If there are multiple instances of hydrogen atoms, sum their total from step 3 and 4.
- Adjust for Moles: If you’re working with a specific number of moles, multiply the total number of hydrogen atoms per molecule by the number of moles and Avogadro's number (6.022 x 10^23) to determine the total number of atoms.
Example
Let's illustrate this with the example of C2H8O, as shown in the video excerpt provided in the references, where it was found to have 32 hydrogen atoms.
| Step | Action | Explanation |
|---|---|---|
| 1 | Identify the Formula | We are given C2H8O |
| 2 | Locate Hydrogen | The symbol "H" represents hydrogen |
| 3 | Note the subscript | The subscript '8' indicates 8 hydrogen atoms |
| 4 | Calculate the Total | 8 hydrogen atoms per molecule. If we had two moles of this substance, it would be 8 2 Avogadro's number |
Additional Notes:
- Coefficients: If a coefficient (a number before a chemical formula) is present in a chemical equation, multiply the number of hydrogen atoms in that molecule by the coefficient.
- Complex Molecules: For more complicated molecules with multiple occurrences of ‘H’ in a single molecule, add the atoms up from step 3 and 4.
Conclusion
Calculating the number of hydrogen atoms is a fundamental skill in chemistry that requires careful observation and basic arithmetic, based on the chemical formula provided.
