Gastric juice contains about $3.0 \mathrm{~g}$ of $\mathrm{HCl}$ per liter. If a person produce about 2.6…
Gastric juice contains about $3.0 \mathrm{~g}$ of $\mathrm{HCl}$ per liter. If a person produce about 2.6 liters of gastric juice per day, find the number of antacid tablets required to neutralise all the $\mathrm{HCl}$ produced. Consider each antacid tablet contains $400 \mathrm{mg}$ of $\mathrm{Al}(\mathrm{OH})_3$.
[Given, atomic masses : $\mathrm{Al}=27, \mathrm{O}=16$, $\mathrm{H}=1, \mathrm{Cl}=35.5]$
8
20
14
10
Solution
Balanced equation is as follows
$
\mathrm{Al}(\mathrm{OH})_3+3 \mathrm{HCl} \longrightarrow \mathrm{AlCl}_3+3 \mathrm{H}_2 \mathrm{O}
$
$
\begin{aligned}
& \text { Aluminium hydrochloric Aluminium } \\
& \text { hydroxide acid chloride } \\
& 27+3(16+1) \quad 3 \times 365 \\
& =78 \mathrm{~g} \quad=109.5 \mathrm{~g} \\
&
\end{aligned}
$
Mass of $\mathrm{HCl}$ produced per day $=3 \times 2.6=7.8 \mathrm{~g}$
Now, stoichiometry indicates that $109.5 \mathrm{~g}$ of $\mathrm{HCl}$ is generated/neutralised by $78 \mathrm{~g}$ of $\mathrm{Al}(\mathrm{OH})_3$.
$7.8 \mathrm{~g}$ of $\mathrm{HCl}$ is neutralised by $\frac{78}{109.5} \times 7.8$
$
=5.556 \mathrm{~g} \text { of } \mathrm{Al}(\mathrm{OH})_3
$
Now, for $400 \mathrm{mg}$ or $\frac{400}{1000} \mathrm{~g}$ of $\mathrm{Al}(\mathrm{OH})_3=1$ tablet
$
\begin{aligned}
\therefore 5.556 \mathrm{~g} \text { of } \mathrm{Al}(\mathrm{OH})_3 & =\frac{1000}{400} \times 5.556 \\
& =13.89 \text { tablets } \\
& =14 \text { antacid tablets. }
\end{aligned}
$