Question

Determine the molecular mass of the following compounds:

(a)

(b)

(c)

(d)

Short answer

The total molecular or formula mass of each compound will be:

(a)56 amu

(b)54 amu

(c)200 amu

(d)97 amu

Step-by-step solution

Determine the molecular mass of part (a)

The molecular mass of a compound is equivalent to the sum of the atomic mass of each element present in that compound.

In, there are 4 carbon and 8 hydrogen atoms, and the atomic mass of 1 carbon and 1 hydrogen atoms is 12 amu and 1 amu, respectively. Therefore, the molecular mass of the compound will be \({\rm{12 }} \times {\rm{ 4 + 1 }} \times {\rm{ 8 = 56 amu}}\)

Determine the molecular mass of part (b)

The molecular mass of a compound is equivalent to the sum of the atomic mass of each element present in that compound.

In, there are 6 hydrogen and 4 carbon atoms, and the atomic mass of 1 hydrogen and 1 carbon atom is 1 amu and 12 amu, respectively. Therefore, the molecular mass of the compound will be \({\rm{1 }} \times {\rm{ 6 + 12 }} \times {\rm{ 4 = 54 amu}}\)

Determine the molecular mass of part (c)

The molecular mass of a compound is equivalent to the sum of the atomic mass of each element present in that compound.

In, there are 2hydrogen, 2 silicon, and 4 chlorine atoms, and the atomic mass of 1 silicon, 1 hydrogen, and 1 chlorine atom is 28 amu, 1 amu, and 35.5 amu, respectively. Therefore, the molecular mass of the compound will be \[{\rm{12 }} \times {\rm{ 28 + 1 }} \times {\rm{ 2 + 35}}{\rm{.5 }} \times {\rm{ 4 = 200 amu}}\]

Determine the molecular mass of part (d)

The molecular mass of a compound is equivalent to the sum of the atomic mass of each element present in that compound.

In, there are 1 phosphorus, 3 hydrogen, and 4 oxygen atoms, and the atomic mass of 1 phosphorus, hydrogen, and oxygen atom is 30 amu, 1 amu, and 16 amu, respectively. Therefore, the molecular mass of the compound will be \({\rm{30 }} \times {\rm{ 1 + 3 }} \times {\rm{ 1 + 16 }} \times {\rm{ 4 = 97 amu}}\)