Question

How many grams of hydrogen gas can be produced from the following reaction when $65$ grams of zinc and $65$ grams of $HCl$ are allowed to react.
$Zn\left( s \right) + 2HCl\left( {aq} \right) \to ZnC{l_2}\left( {aq} \right) + {H_2}\left( g \right)$

Answer 1

We must remember that hydrogen is a colourless, odourless, tasteless, non-toxic, non-metallic, highly combustible diatomic gas with the molecular formula $H_2$ at normal temperature and pressure. Since hydrogen easily forms covalent compounds with most non-metallic elements, molecular forms such as water or organic compounds comprise most of the hydrogen on Earth.
Zinc is a vital mineral which is used in countless ways by your body. In fact, zinc is the second most abundant trace mineral in your body and is present in every cell after iron .More than $300$ enzymes that help in metabolism, digestion, nerve function and many other processes need zinc for the action.

Complete step by step answer:
$Zn\left( s \right) + 2HCl\left( {aq} \right) \to ZnC{l_2}\left( {aq} \right) + {H_2}\left( g \right)$
One mole of Zn reacts with 2 moles of $HCl$ to produce one mole of hydrogen.
atomic mass of $Zn{\text{ = }}65.4g/mol$ ,molar mass of $HCl{\text{ = }}36.5g/mol$ .
When we divide mass with atomic or molar mass, we get number of moles.
Number of moles of Zinc $= 65.465 = 0.994$ moles .
Number of moles of $HCl = 36.565 = 1.78$ moles.
$0.994$ moles of Zn will react with $2 \times 0.994 = 1.988$ moles of HCl however $1.78$ moles of HCl are present. Hence, $HCl$ is the limiting reactant.
$1.78$ moles of $HCl$ will produce $21.78 = 0.89$ moles of ${H_2}$
The molar mass of ${H_2}$​ is $2g/mol$ .
Mass of ${H_2}$ obtained $= 2g/mol \times 0.89mol = 1.78g = 1.8g$

Note:
We must remember that the zinc is a nutrient required by individuals to remain healthy. In cells all over the body, zinc is present. It helps fend off invading bacteria and viruses from the immune system. To produce proteins and DNA, the genetic material of all cells, the body also requires zinc. The body requires zinc to grow and develop properly during pregnancy, infancy, and childhood.
The atomic mass is the weighted average of all the isotopes of that element, in which the abundance of that particular isotope is multiplied by the mass of each isotope. (The atomic mass is also known as atomic weight, but the word "mass" is more precise).