Question

Ascorbic acid (vitamin C) is important in many metabolic reactions in the body, including the synthesis of collagen and prevention of scurvy. Given that themass percent composition of ascorbic acid is 40.9% C, 4.58% H, and 54.5% O, determine the empirical formula of ascorbic acid. Show all your work

Answer 1

Empirical formula:

Step 1

Information already provided

The mass percent composition:

40.9 % C

4.58 % H

54.5 % O

Information needed: from the periodic table

For C) 1 mol = 12.01 g

For H) 1 mol = 1.008 g

For O) 1 mol = 15.99 g

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Step 2

A sample of 100 g is assumed, so:

40.9 % C => 40.9 g C

4.58 % H => 4.58 g H

54.5 % O => 54.5 g O

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Step 3

Convert mass into moles:

40.9 g C x (1 mol/12.01 g) = 3.40 moles C

4.58 g H x (1 mol/1.008 g) = 4.54 moles H

54.5 g O x (1 mol/15.99 g) = 3.40 moles O

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Step 4

All moles calculated in step 3 need to be divided by the smallest one.

3.40 moles C/3.40 moles = 1

4.54 moles H/3.40 moles = 1.33

3.40 moles O/3.40 moles = 1

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Step 5

Integer numbers are needed, so let's multiply by 3 all of them in step 4

Therefore,

For C) 3

For H) 3.99 = 4 approx.

For O) 3

All these numbers calculated will be the subindexes in ascorbic acid

Answer:

Empirical formula: C3H4O3