An organic molecule contains 70.6% Carbon, 5.9% Hydrogen and 23.5% Oxygen. It has a molecular mass of 136. What is its chemical formula? A. C4H4O B. C5H4O C. C8H8O2 D. C10H8O2 E. C2H2O

To find the chemical formula of the organic molecule, we need to follow these steps:

1. Assume that we have 100g of the compound. This means we have 70.6g of Carbon (C), 5.9g of Hydrogen (H), and 23.5g of Oxygen (O).

2. Convert these masses to moles. We do this by dividing the mass of each element by its atomic mass. The atomic mass of C is approximately 12g/mol, H is approximately 1g/mol, and O is approximately 16g/mol.

   Moles of C = 70.6g / 12g/mol = 5.88 mol Moles of H = 5.9g / 1g/mol = 5.9 mol Moles of O = 23.5g / 16g/mol = 1.47 mol

3. To find the simplest whole number ratio of these atoms, divide each number of moles by the smallest number of moles calculated. In this case, the smallest number is 1.47.

   Ratio of C = 5.88 / 1.47 = 4 Ratio of H = 5.9 / 1.47 = 4 Ratio of O = 1.47 / 1.47 = 1

4. Therefore, the empirical formula of the compound is C4H4O.

5. The molecular formula is a multiple of the empirical formula. To find this multiple, divide the molecular mass by the mass of the empirical formula. The mass of the empirical formula is (412) + (41) + 16 = 64.

   Multiple = 136 / 64 = 2

6. Multiply the subscripts in the empirical formula by this multiple to get the molecular formula: C8H8O2.

So, the answer is C. C8H8O2.