Question

Which of the following atoms contains the largest mass of H-atoms?
A) $5\,mol$ ${C_2}{H_2}{O_4}$
B) $1.1\,mol$ ${C_3}{H_8}{O_3}$
C) $1.5\,mol$ ${C_6}{H_8}{O_6}$
D) $4\,mol$ ${C_2}{H_4}{O_2}$

Answer 1

To solve this question, use the unitary method in mole concept. Calculate the mass of the Hydrogen atom in 1 mole of compound and then calculate the mass for the required number of moles using the unitary method. And at the last, simply compare the masses and you will get your answer.

Complete step-by-step solution:
Here {g refers to gram (mass)}
Step 1. For ${C_2}{H_2}{O_4}$ :- 1 mole of ${C_2}{H_2}{O_4}$ contains $\to$ 2 moles of H-atom $= 2 \times 1 = 2$ g of H-atom.
So, 5 moles of ${C_2}{H_2}{O_4}$ contains $\to$ $5 \times 2$ g $= 10$ g of H-atoms.

Step 2. For ${C_3}{H_8}{O_3}$ :- 1 mole of ${C_3}{H_8}{O_3}$ contains $\to$ 8 moles of H-atom $= 8 \times 1 = 8$ g of H-atom.
So, 1.1 moles of ${C_3}{H_8}{O_3}$ contains $\to$ $1.1 \times 8$ g $= 8.8$ g of H-atoms.

Step 3. For ${C_6}{H_8}{O_6}$ :- 1 mole of ${C_6}{H_8}{O_6}$ contains $\to$ 8 moles of H-atom $= 8 \times 1 = 8$ g of H-atom.
So, 1.5 moles of ${C_6}{H_8}{O_6}$ contains $\to$ $1.5 \times 8$ g $= 15$ g of H-atom.

Step 4. For ${C_2}{H_4}{O_2}$ :- 1 mole of ${C_2}{H_4}{O_2}$ contains $\to$ 4 moles of H-atom $= 4 \times 1 = 4$ g of H-atom.
So, 4 moles of ${C_2}{H_4}{O_2}$ contains $\to$ $4 \times 4 = 16$g of H-atom.
So, by comparing all the masses we can conclude that 4 moles of ${C_2}{H_4}{O_2}$ will contain the greatest mass of H-atoms.

Hence, option D is the correct answer.

Note: A substance's molar mass is calculated by multiplying its relative atomic mass by the molar mass constant (1 g/mol). The molar mass constant can be used to convert mass to moles. By multiplying a given mass by the molar mass, the amount of moles of the substance can be calculated.