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A compound has a mass percent composition of 58.8% C, 9.86% H and 31.32% O. The molar mass of the compound is 306.39 g/mol.

(a) Calculate the empirical formula.

(b) Calculate the molecular formula

Enter your answers using the following format for a formula: C3H3O3

2 Answers

10 votes

Final answer:

The empirical formula of the compound is C2H5O, and the molecular formula is C6H13O3.

Step-by-step explanation:

To determine the empirical formula of a compound, we need to convert the percentage composition of each element into the number of moles. We can then divide each mole value by the smallest mole value to get the simplest ratio of atoms, which represents the empirical formula.

In this case, we assume we have 100g of the compound. That means we have 58.8g of Carbon, 9.86g of Hydrogen, and 31.32g of Oxygen.

Now we can convert the mass of each element into moles using their molar masses. The molar mass of Carbon is 12.01 g/mol, Hydrogen is 1.01 g/mol, and Oxygen is 16.00 g/mol.

So, for Carbon: 58.8g / 12.01 g/mol = 4.898 mol

For Hydrogen: 9.86g / 1.01 g/mol = 9.763 mol

And for Oxygen: 31.32g / 16.00 g/mol = 1.9585 mol

Next, we divide each mole value by the smallest mole value to get the simplest ratio of atoms. In this case, the smallest mole value is 1.9585, so we divide all the moles by 1.9585.

The ratios become approximately:

  • Carbon: 4.898 mol / 1.9585 mol = 2.5 (approximately)
  • Hydrogen: 9.763 mol / 1.9585 mol = 4.99 (approximately)
  • Oxygen: 1.9585 mol / 1.9585 mol = 1

Rounding the ratios to the nearest whole number, we get the empirical formula of the compound as C2H5O.

To determine the molecular formula, we need to know the molar mass. In this case, the molar mass is given as 306.39 g/mol. To find the molecular formula, we divide the molar mass by the empirical formula mass.

For C2H5O, the empirical formula mass is: 2(12.01) + 5(1.01) + 16.00 = 46.08 g/mol.

Dividing the molar mass (306.39 g/mol) by the empirical formula mass (46.08 g/mol), we get approximately 6.653.

Since we can't have fractions in a molecular formula, we need to round the number to the nearest whole number. So, the molecular formula of the compound is C6H13O3.

User Rtacconi
by
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7 votes

The solution would be like this for this specific problem:

Moles of carbon = 58.8 / 12 = 4.9

Moles of hydrogen = 9.8 / 1 = 9.8

Moles of oxugen = 31.4 / 16 m= 1.96

Ratio 4.9 / 1.96 = 2.5 9.8 / 1.96 = 5.0 1.96 / 1.96 = 1

Simplest formula = C5H10

I hope this helps and if you have any further questions, please don’t hesitate to ask again.

User Bluedaniel
by
3.4k points