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