16. Formaldhyde has a mole ratio of 1 mole C: 2 moles H: 1 mole O. Its empirical formula is the same as its

molecular formula. How many grams are in 3.25 moles of formaldehyde?

a. 30.03 g

c. 75.08 g

b. 60.06 g

d. 97.60 g

d. 97.60 g

Explanation:

Given parameters:

Number of moles of formaldehyde = 3.25moles

Ratio:

C H O

1 2 1

Unknown:

Mass of this sample = ?

Solution:

The empirical formula of a compound is its simplest formula. It is the simplest whole number ratio of the atoms in a given substance.

The molecular formula is the actual formula of the compound.

Since the molecular and empirical formula are the same here, the formula of the compound is;

CH₂O

To find the mass of the formaldehyde, use the expression below;

Mass = number of moles x molar mass

molar mass of CH₂O = 12 + 2 (1) + 16 = 30g/mol

Mass = 3.25 x 30 = 97.5g