To calculate the compound weight (also known as molar mass or molecular weight) of a chemical compound, you'll sum the atomic weights of each element in the compound, taking into account the number of atoms of each element present. Here's the step-by-step process:
1. Identify the Chemical Formula:
First, you need the correct chemical formula for the compound. This formula tells you which elements are present and the number of atoms of each. For example, water has the formula H₂O, indicating two hydrogen atoms and one oxygen atom.
2. Find the Atomic Weights:
Next, find the atomic weight of each element in the compound. You can find these values on the periodic table or in a reliable chemical reference. Atomic weights are typically expressed in atomic mass units (amu) or grams per mole (g/mol).
3. Multiply and Sum:
Multiply the atomic weight of each element by the number of atoms of that element in the compound. Then, add up all the resulting values. This sum represents the compound weight.
Example: Calculating the Compound Weight of Water (H₂O)
Here's how to calculate the compound weight of water (H₂O):
| Element | Number of Atoms | Atomic Weight (g/mol) | Total Mass (g/mol) |
|---|---|---|---|
| Hydrogen (H) | 2 | 1.008 | 2 * 1.008 = 2.016 |
| Oxygen (O) | 1 | 16.00 | 1 * 16.00 = 16.00 |
| Total | 18.016 |
Therefore, the compound weight (molar mass) of water (H₂O) is approximately 18.016 g/mol.
Example: Calculating the Compound Weight of Sodium Chloride (NaCl)
Here's how to calculate the compound weight of sodium chloride (NaCl):
| Element | Number of Atoms | Atomic Weight (g/mol) | Total Mass (g/mol) |
|---|---|---|---|
| Sodium (Na) | 1 | 22.99 | 1 * 22.99 = 22.99 |
| Chlorine (Cl) | 1 | 35.45 | 1 * 35.45 = 35.45 |
| Total | 58.44 |
Therefore, the compound weight (molar mass) of Sodium Chloride (NaCl) is approximately 58.44 g/mol.
In summary, to calculate the compound weight, identify the chemical formula, find the atomic weights of each element, multiply each atomic weight by the number of atoms of that element in the formula, and sum the results.
