Final answer:
The student went wrong in their calculation by incorrectly calculating the molar mass of CO₂ as 28 g/mol instead of the correct value of 44.01 g/mol.
Step-by-step explanation:
The student went wrong in their calculation by incorrectly calculating the molar mass of CO₂. The correct molar mass of CO₂ is 44.01 g/mol, not 28 g/mol. The molar mass of a compound is calculated by adding up the atomic masses of all the atoms in the compound.
For CO₂, the molar mass is calculated as follows: 1 atom of carbon (C) with an atomic mass of 12.01 g/mol + 2 atoms of oxygen (O) with an atomic mass of 15.999 g/mol each. Adding these up, we get: 12.01 g/mol + 2(15.999 g/mol) = 44.01 g/mol.
Therefore, the student made an error in calculating the molar mass, leading to their incorrect answer of 28 g/mol for CO₂.