Question

What is the molecular formula of a compound that contains 10.0g carbon, 1.68g hydrogen, and 13.4g oxygen? The molar mass of this compound is 150.0g/mol.

Select the correct answer below:
A) CHO
B) CH₂O
C) C₅H₁₀O₅
D) C₆H₁₂O₆

Answer 1

The molecular formula of the compound is C5H10O5.

Step-by-step explanation:

The molecular formula of a compound is determined by the ratio of atoms present in the compound. To find the molecular formula, we need to calculate the mole ratio of each element using their molar masses and the given masses of carbon, hydrogen, and oxygen. The molar mass of the compound is 150.0g/mol.

First, we calculate the moles of each element by dividing their mass by their respective molar mass:

1. Carbon: 10.0g / 12.01 g/mol = 0.832 mol
2. Hydrogen: 1.68g / 1.008 g/mol = 1.667 mol
3. Oxygen: 13.4g / 16.00 g/mol = 0.838 mol

The mole ratio for each element is approximately:

1. Carbon: 0.832 mol / 0.832 mol = 1
2. Hydrogen: 1.667 mol / 0.832 mol = 2
3. Oxygen: 0.838 mol / 0.832 mol = 1

The empirical formula of the compound is CH2O. To determine the molecular formula, we need to know the molar mass of the empirical formula. The molar mass of CH2O is:

1 * (12.01 g/mol) + 2 * (1.008 g/mol) + 16.00 g/mol = 30.03 g/mol

To find the multiplier that will give us the molecular formula, we divide the molar mass of the compound by the molar mass of the empirical formula:

150.0 g/mol / 30.03 g/mol = 4.99 ≈ 5

Multiplying the empirical formula by 5, we get the molecular formula: C5H10O5

Answer 2

To find the molecular formula, we can calculate the moles of each element, find the mole ratio of the elements, and determine the simplest whole-number ratio. The molecular formula is CH₂O, and the correct answer is B) CH₂O

Step-by-step explanation:

To determine the molecular formula, we need to follow these steps:

1. Calculate the number of moles of each element using their given masses and molar masses.

2. Find the simplest whole-number ratio of moles for each element.

3. Write the molecular formula using the whole-number ratio.

Let's go through the calculations:

a) Carbon (C):

Moles of C =
`\frac{\text{Mass of } C}{\text{Molar mass of } C}`

=
`\frac{10.0 \, \text{g}}{12.01 \, \text{g/mol}}`

≈ 0.832 mol

b) Hydrogen (H):

Moles of H =
`\frac{\text{Mass of } H}{\text{Molar mass of } H}`

=
`\frac{1.68 \, \text{g}}{1.01 \, \text{g/mol}}`

≈ 1.667 mol

c) Oxygen (O):

Moles of O =
`\frac{\text{Mass of } O}{\text{Molar mass of } O}`

=
`\frac{13.4 \, \text{g}}{16.00 \, \text{g/mol}}`

≈ 0.838 mol

Now, find the simplest whole-number ratio. It is approximately 1:2:1 for C:H:O.

So, the molecular formula is CH₂O, and the correct answer is:

B) CH₂O