Question

How many grams of trinitrotoluene [${{C}_{7}}{{H}_{5}}{{(N{{O}_{2}})}_{3}}$] are in 0.00892 moles of TNT?

Answer 1

Hint: The formula that can be used for solving this question will be:
$Moles=\dfrac{Given\text{ }mass}{Molecular\,mass}$
To find the molecular mass you can use, the atomic mass of carbon as 12, the atomic mass of hydrogen as 1, the atomic mass of nitrogen as 14, and the atomic mass of oxygen as 16.

Complete answer:
TNT is an organic compound whose formula is given as [${{C}_{7}}{{H}_{5}}{{(N{{O}_{2}})}_{3}}$], in this compound there is an aromatic ring or benzene ring, at the first carbon there is a methyl group, and at 2, 4, 6 positions there is a nitro group. The structure of TNT is given below:

So, the given number of moles of trinitrotoluene is 0.00892 and we have to find the grams in these given moles. The formula that can be used for solving this question will be:
$Moles=\dfrac{Given\text{ }mass}{Molecular\,mass}$
So, we have to calculate the molecular mass. We can calculate the molecular mass by adding the atomic masses of the elements in the compound. The atomic mass of carbon is 12, the atomic mass of hydrogen is 1, the atomic mass of nitrogen is 14 and the atomic mass of oxygen is 16. The molecular mass will be:
$12\text{ x 7 + 1 x 5 + 3 x 14 + 6 x 16 = 227}$
So, now we can calculate the grams by multiplying the given moles with molecular mass.
Mass = moles x molecular mass
Mass = 0.00892 x 227 = 2.024 grams
So, there are 2.024 grams present in 0.00892 moles of TNT.

Note: We can also take the exact atomic mass of the atoms to solve the molecular mass of the compound. The mass is taken in grams because the atomic and molecular masses are in gram /mol.