Question

A component of protein called serine has an approximate molar mass of 100 g/mole. If the percent composition is as follows, what is the molecular formula of serine? C = 34.95% H = 6.844% O = 46.56% N = 13.59%?

Answer 1

To determine the molecular formula of serine, we can calculate the number of moles for each element based on the given percent composition and then find the simplest whole number ratio of these moles.

Given percent compositions: C = 34.95% H = 6.844% O = 46.56% N = 13.59%

Let's assume we have 100 grams of serine to make calculations easier.

1. Calculate the mass of each element based on the percent composition: C: 34.95 g H: 6.844 g O: 46.56 g N: 13.59 g

2. Calculate the number of moles for each element using their molar masses: C: moles = mass (g) / molar mass (g/mol) = 34.95 g / 12.01 g/mol = 2.911 mol H: moles = mass (g) / molar mass (g/mol) = 6.844 g / 1.008 g/mol = 6.792 mol O: moles = mass (g) / molar mass (g/mol) = 46.56 g / 16.00 g/mol = 2.91 mol N: moles = mass (g) / molar mass (g/mol) = 13.59 g / 14.01 g/mol = 0.970 mol

3. Find the simplest whole number ratio by dividing the moles of each element by the smallest number of moles (0.970 in this case): C: 2.911 mol / 0.970 mol = 3.00 (approximately) H: 6.792 mol / 0.970 mol = 7.00 (approximately) O: 2.91 mol / 0.970 mol = 3.00 (approximately) N: 0.970 mol / 0.970 mol = 1.00

Based on these ratios, we can determine the empirical formula of serine, which is C3H7NO3.