Question

Find the molecular mass of the following compounds:
Sulphuric acid $({{H}_{2}}S{{O}_{4}})$
Potassium nitrate $(KN{{O}_{3}})$
Hydrogen sulphide $({{H}_{2}}S)$
Carbon dioxide $(C{{O}_{2}})$

Answer 1

Hint: Before answering this question, we should know what is Molecular mass? The molecular mass is the summation of the masses of the atoms or elements that is there in the molecule. It is measured in daltons. Now we can easily find the value of the compounds that are asked in the question.

Complete answer:
How to calculate the molecular mass of the molecule?
We can find it through these steps-
Identify the formula of the compound.
With the help of the formula, find out the number of atoms that are present in each element of the compound.
The atomic weight of each element should be multiplied by the number of atoms of that element.
Follow the same procedure for all the elements in the compound.
Find the total sum of all the values determined in the above step.
Then, using the unit grams/mole, we will be able to determine the molecular mass of the substance.
Now, we have to determine the molecular formula of the given compounds:
$({{H}_{2}}S{{O}_{4}})$
The molecular mass of $({{H}_{2}}S{{O}_{4}})$= 2$\times $Atomic mass of Hydrogen + Atomic mass of Sulphur + 4$\times $Atomic mass of Oxygen.
The atomic mass of Hydrogen= 1
The atomic mass of Sulphur= 32
The atomic mass of Oxygen= 16
So, the molecular mass of $({{H}_{2}}S{{O}_{4}})$= 2+32+64
                                                           = 98
$(C{{O}_{2}})$
The molecular mass of$(C{{O}_{2}})$= Atomic mass of carbon + 2(Atomic mass of oxygen)
The atomic mass of carbon = 12
The atomic mass of oxygen = 16
So, the molecular mass of$C{{O}_{2}}$= 12+2(16)
                                                  = 12+32
                                                  = 44

 $(KN{{O}_{3}})$
The molecular mass of $(KN{{O}_{3}})$ = Atomic mass of potassium + Atomic mass of nitrogen + 3$\times $Atomic mass of Oxygen.
The atomic mass of potassium= 40
The atomic mass of nitrogen= 14
The atomic mass of oxygen= 16
So, the molecular mass of $(KN{{O}_{3}})$= 40+14+48
                                                         = 102
$({{H}_{2}}S)$
The molecular mass of $({{H}_{2}}S)$ = 2$\times $Atomic mass of hydrogen + Atomic mass of sulphur
                                                   = 2$\times $1 + 32
                                                   = 34


Note:
The difference between the molar mass and molecular mass is that the mass of a mole of a particular substance is given by the molar mass whereas the mass of a molecule of a particular substance is given by molecular mass. The value of both comes out to be the same but they have different units.