Question

What is the mass of $4$ moles of ${C_3}{H_8}$?

Answer 1

Hint: We need to know the difference between mass of a molecule and the molecular mass of a compound. In order to calculate the mass of a molecule, we first need to define the molecular mass of that molecule of the given compound. With the given molecular formula of a compound and the atomic masses of its constituent elements, we calculate the molecular mass of a given compound.

Complete answer:
We have to know that the molecular mass of a compound is calculated using the following rules:
The atomic masses of each of the elements constituting the given compound must be known.
We multiply the atomic mass of a particular element to the number of that element present in the compound (written in the form of subscript of the element in the molecular formula).
We add up all the resulting numbers and obtain the molecular mass in grams/mole.
The density of a sample of a chemical compound divided by the volume of material in that sample, estimated in moles, is the molar mass of that compound in chemistry. In grammes, that is the mass of $1$ mole of the material, or particles.
To calculate the mass of $4$ moles of ${C_3}{H_8}$, we first calculate the mass of $1$ mole of ${C_3}{H_8}$ using the above rules.
Molar mass of ${C_3}{H_8}$ is $12 \cdot 3 + 1 \cdot 8 = 44g/mol$
Hence, the mass of $4$ moles of ${C_3}{H_8}$= $4 \times 44g/mol = 176g$

Note:
It's worth noting that the molar mass of a compound is known by many common names. The density of one mole of a substance in grammes per mole is referred to as molecular mass, molecular weight, or gramme formula mass, among other terms. Even, though the atomic masses of the various elements in a periodic table are often decimals, for the sake of simplicity, the estimated entire integer is used in calculations.