Final answer:
The repeat unit molecular weight of polyethylene is calculated by summing the atomic weights of its empirical formula, CH₂, which yields a molecular weight of 14.026 g/mol.
Step-by-step explanation:
To calculate the repeat unit molecular weight of polyethylene, we will consider its empirical formula which is CH₂. The molecular weight is simply the sum of the weights of one carbon atom and two hydrogen atoms. The atomic weights from the periodic table that we will use are approximately: Carbon = 12.01 g/mol and Hydrogen = 1.008 g/mol.
Adding up these atomic weights:
- Molecular weight of Carbon (C) = 12.01 g/mol
- Molecular weight of Hydrogen (H₂) = 1.008 g/mol × 2 = 2.016 g/mol
Now, we sum the molecular weights to get the molecular weight of the repeat unit in polyethylene:
12.01 g/mol (for C) + 2.016 g/mol (for H₂) = 14.026 g/mol
Therefore, the repeat unit molecular weight of polyethylene is 14.026 g/mol.