Question

How many grams of hydrogen is present in8.5g $N{H_{_3}}$ ?
A.1.5
B.0.5
C.0.08
D.None of the above

Answer 1

Hint: To calculate the gram atoms of hydrogen we should first calculate the number of moles of hydrogen. After that we will divide the given mass by the molar mass of N and then multiply by the number of moles of H atom.
Complete step by step answer:
One-gram atom is basically the atomic weight of an element. Basically, the mass of an element which is numerically equal to the atomic weight in grams is known as gram atom. Now, let’s calculate the gram atom of hydrogen in8.5g $N{H_{_3}}$ .
Now, mass of one mole of ammonia =17
Mass of H atom per mole of $N{H_{_3}} = 3$
Therefore, 8.5g $N{H_{_3}}$ will have
 $
   = 3 \times \dfrac{{8.5}}{{17}} \\
    \\
 $
=1.5Moles of hydrogen

Hence, option A is correct.

Additional information:

The gram formula mass of a compound is basically the amount of that compound that has the same mass in grams and the formula mass in the atomic mass unit. Moreover, an atom of each element has a characteristic mass and each molecule of a compound has a characteristic formula mass. So, when the formula mass of an ionic compound is determined by the addition of its component atomic masses and expressed in grams then, it is called as gram formula mass.

Note: In chemistry, a mole is defined as the amount of a substance that contains exactly $6.022 \times {10^{23}}$ elementary entities of the given substance. Moreover, this number is known as Avogadro constant and is denoted by ${N_A}$ .The elementary entities that can be represented in moles are atoms, molecules, electrons etc.