You're asking to calculate the molar mass of potassium hydrogen phthalate (KHC8H4O4), not just the "approximate mass." Here's how to do that:

1. Look up the atomic masses of each element:

* Potassium (K): 39.10 g/mol

* Hydrogen (H): 1.01 g/mol

* Carbon (C): 12.01 g/mol

* Oxygen (O): 16.00 g/mol

2. Multiply the atomic mass of each element by the number of atoms of that element in the molecule:

* K: 39.10 g/mol * 1 = 39.10 g/mol

* H: 1.01 g/mol * 5 = 5.05 g/mol

* C: 12.01 g/mol * 8 = 96.08 g/mol

* O: 16.00 g/mol * 4 = 64.00 g/mol

3. Add up the masses of all the elements:

39.10 g/mol + 5.05 g/mol + 96.08 g/mol + 64.00 g/mol = 204.23 g/mol

Therefore, the molar mass of KHC8H4O4 is approximately 204.23 g/mol.