Problem: Vitamin C is known chemically by the name ascorbic acid. Determine the empirical formula of ascorbic acid if it is composed of 40.92% carbon, 4.58% hydrogen, and 54.50% oxygen.

We’re being asked to determine the empirical formula of ascorbic acid if it is composed of 40.92% carbon, 4.58% hydrogen, and 54.50% oxygen.

This means we need to do the following steps:

Step 1: Calculate the mass and moles of C, H, and O in the compound.

Step 2: Determine the lowest whole number ratio of C, H, and O to get the empirical formula.

Step 1: The compound is composed of C, H, O and we’re given the mass percent of C (40.92% C), H (4.58% H) and O (54.50% O). 

Check if the mass percentages of the compound add up to 100%. 

This means:

$$\begin{gathered} \boxed{\mathbf{Total}\mathbf{ }\mathbf{mass}\mathbf{\%}\mathbf{ }\mathbf{=}\mathbf{ }\mathbf{mass}\mathbf{\%}\mathbf{ }\mathbf{C}\mathbf{ }\mathbf{+}\mathbf{ }\mathbf{mass}\mathbf{\%}\mathbf{H}\mathbf{ }\mathbf{+}\mathbf{ }\mathbf{mass}\mathbf{\%}\mathbf{ }\mathbf{O}} \\ \mathbf{Total}\mathbf{ }\mathbf{mass}\mathbf{ }\mathbf{\%}\mathbf{ }\mathbf{=}\mathbf{ }\mathbf{40}\mathbf{.}\mathbf{92}\mathbf{\%}\mathbf{ }\mathbf{+}\mathbf{ }\mathbf{4}\mathbf{.}\mathbf{58}\mathbf{\%}\mathbf{+}\mathbf{ }\mathbf{54}\mathbf{.}\mathbf{50}\mathbf{\%} \\ \mathbf{Total}\mathbf{ }\mathbf{mass}\mathbf{\%}\mathbf{ }\mathbf{=}\mathbf{ }\mathbf{100}\mathbf{.}\mathbf{00}\mathbf{\%} \end{gathered}$$

Recall that mass percent is given by:

$\boxed{\mathbf{\%}\mathbf{mass}\mathbf{ }\mathbf{=}\mathbf{ }\frac{\mathbf{mass}\mathbf{ }\mathbf{X}}{\mathbf{Total}\mathbf{ }\mathbf{mass}}\mathbf{x}\mathbf{100}}$

Assuming we have 100 g of the compound, this means we have 40.92 g C, 4.58 g H, and 54.50 g O. 

Now, we need to get the moles of each element in the compound. 

The atomic masses are 12 g/mol C, 1 g/mol H, 16 g/mol O.