Question

Equal lengths magnesium ribbons are taken in test tubes A and B. Hydrochloric acid $\left( {{\rm{HCl}}} \right)$ is added to test tube A, while acetic acid $\left( {{\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{COOH}}} \right)$ is added to test tube B. Amount and concentration taken for both the acids are same. In which test tube will the fizzing occur more vigorously and why?

Answer 1

Hint: Fizzing occurs in a chemical reaction due to the presence of gas. To identify the test tube where fizzing occurs more vigorously, we have to compare to compare the acidity of the ${\rm{HCl}}$ and ${\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{COOH}}$.

Equal sizes of ribbons of magnesium are taken in two test tubes namely, A and B. ${\rm{HCl}}$ (Hydrochloric acid) is added to A test tube and ${\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{COOH}}$ (acetic acid) is added to B test tube. Magnesium is a metal and reaction of metal with acid produces hydrogen gas and salt.

Now, we have to write the reaction takes places in test tube A,

${\rm{Mg}}\left( s \right) + 2{\rm{HCl}}\left( {aq} \right) \to {\rm{MgC}}{{\rm{l}}_{\rm{2}}}(aq) + {{\rm{H}}_{\rm{2}}}\left( g \right)$

Then, write the reaction takes place in test tube B.

${\rm{Mg}}\left( s \right) + {\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{COOH}}\left( {aq} \right) \to {\rm{Mg}}{\left( {{\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{COO}}} \right)_2}(aq) + {{\rm{H}}_{\rm{2}}}\left( g \right)$

From the above reactions we all get to know that hydrogen gas is produced in both the test tubes. Now we have to identify the test tube where more vigorous fizzing occurs. We know that hydrochloric acid is more reactive than acetic acid. So, liberation of hydrogen gas from test tube A (containing ${\rm{HCl}}$) is more vigorous than from test tube A.

Note: In the question, two acids are given, namely hydrochloric acid and acetic acid and both react with magnesium. The hydrogen produced in both the reaction results fizzing. The more fizzing is observed in case of reaction of magnesium with hydrochloric acid as HCl is more reactive than acetic acid.