Metals react with acids to produce which gas

Hint: Try to understand the role of mineral acid in the above reaction. They are used as a protonating agent as they release hydrogen ions in aqueous solution. To solve the question, take a simple metal, say zinc and write its reaction with an acid like sulphuric acid. The above reaction is a redox reaction i.e. one atom gets oxidized and another atom will be reduced.

Complete step-by-step answer:
Metals are good reducing agents as they easily get oxidised. This is because they have electrons which can be easily released.
The hydrogen ions in the aqueous solution of the acid accept these electrons and hence get reduced. This leads to the formation of molecular hydrogen.
We will now consider a metal, let's say zinc. We will now write its reaction with a strong mineral acid like sulphuric acid.
$Z{{n}_{(s)}}+{{H}_{2}}S{{O}_{4}}\to \text{ }Z{{n}^{2+}}+S{{O}_{4}}^{2-}+{{H}_{2\uparrow }}$
The reaction given above is a redox reaction i.e. oxidation and reduction takes place simultaneously in a single reaction.
Therefore, from the above reaction we can conclude that the gas released is hydrogen.

The correct answer is option (D).

Note: The reaction of metals with acids is a standard reaction to check the presence of metal in a given solution. However, some metals react with bases as well and release hydrogen gas. These metals are called amphoteric metals. Examples of some amphoteric metals are zinc, aluminium etc. The reaction between zinc and a base( in this case sodium hydroxide) is given below:
$Z{{n}_{(s)}}+2NaOH\to \text{ }N{{a}_{2}}Zn{{O}_{2}}+{{H}_{2}}$

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Learning Objectives
Neutralization Reactions
1. Example $\PageIndex{1}$: Propionic Acid + Calcium Hydroxide
  1. Solution
2. Exercise $\PageIndex{1}$
Acids and Bases React with Metals

Learning Objectives

Write acid-base neutralization reactions.
Write reactions of acids with metals.
Write reactions of bases with metals.

Neutralization Reactions

The reaction that happens when an acid, such as $\ce{HCl}$, is mixed with a base, such as $\ce{NaOH}$:

\[\ce{HCl (aq) + NaOH (aq) → NaCl (aq) + H_2O (l)}\nonumber \]

When an acid and a base are combined, water and a salt are the products. Salts are ionic compounds containing a positive ion other than $\ce{H^{+}}$ and a negative ion other than the hydroxide ion, $\ce{OH^{-}}$. Double displacement reactions of this type are called neutralization reactions. We can write an expanded version of this equation, with aqueous substances written in their longer form:

\[\ce{H^{+} (aq) + Cl^{-} (aq) + Na^{+} (aq) + OH^{-} (aq) → Na^{+} (aq) + Cl^{-} (aq) + H_2O (l)}\nonumber \]

After removing the spectator ions, we get the net ionic equation:

\[\ce{H^{+} (aq) + OH^{-} (aq) → H_2O (l)}\nonumber \]

When a strong acid and a strong base are combined in the proper amounts—when $[\ce{H^{+}}]$ equals $[\ce{OH^{-}}$]\)—a neutral solution results in which pH = 7. The acid and base have neutralized each other, and the acidic and basic properties are no longer present.

Salt solutions do not always have a pH of 7, however. Through a process known as hydrolysis, the ions produced when an acid and base combine may react with the water molecules to produce a solution that is slightly acidic or basic. As a general concept, if a strong acid is mixed with a weak base, the resulting solution will be slightly acidic. If a strong base is mixed with a weak acid, the solution will be slightly basic.

Video: Equimolar (~0.01 M) and equivolume solutions of $\ce{HCl}$ and $\ce{NaOH}$ are combined to make salt water. https://youtu.be/TS-I9KrUjB0

Example $\PageIndex{1}$: Propionic Acid + Calcium Hydroxide

Calcium propionate is used to inhibit the growth of molds in foods, tobacco, and some medicines. Write a balanced chemical equation for the reaction of aqueous propionic acid (CH3CH2CO2H) with aqueous calcium hydroxide [Ca(OH)2].

SolutionSolutions to Example 14.5.1StepsReaction

Write the unbalanced equation.

This is a double displacement reaction, so the cations and anions swap to create the water and the salt.

CH3CH2CO2H(aq) + Ca(OH)2(aq)→(CH3CH2CO2)2Ca(aq) + H2O(l)

Balance the equation.

Because there are two OH− ions in the formula for Ca(OH)2, we need two moles of propionic acid, CH3CH2CO2H, to provide H+ ions.

2CH3CH2CO2H(aq) + Ca(OH)2(aq)→(CH3CH2CO2)2Ca(aq) +2H2O(l)

Exercise $\PageIndex{1}$

Write a balanced chemical equation for the reaction of solid barium hydroxide with dilute acetic acid.

Answer

\[\ce{Ba(OH)2(s) + 2CH3CO2H (aq)→Ba(CH3CO2)2 (aq) + 2H2O(l)} \nonumber \nonumber \]

Acids and Bases React with Metals

Acids react with most metals to form a salt and hydrogen gas. As discussed previously, metals that are more active than acids can undergo a single displacement reaction. For example, zinc metal reacts with hydrochloric acid, producing zinc chloride and hydrogen gas.

\[\ce{Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)}\nonumber \]

Bases also react with certain metals, like zinc or aluminum, to produce hydrogen gas. For example, sodium hydroxide reacts with zinc and water to form sodium zincate and hydrogen gas.

\[\ce{Zn(s) + 2NaOH (aq) + 2H2O(l) → Na2Zn(OH)4(aq) + H2 (g)}.\nonumber \]

14.5: Reactions of Acids and Bases is shared under a Public Domain license and was authored, remixed, and/or curated by Marisa Alviar-Agnew, Henry Agnew, Peggy Lawson, & Peggy Lawson.