Facts on HCl + Al: With Several Elements Reaction

Hydrochloric acid is a very strong acid as it has the capability to dissociate almost completely. Let us examine some facts when Hydrochloric acid (HCl) reacts with Aluminium (Al).

Hydrochloric acid is also referred to as muriatic acid. In appearance, it seems to be colorless, and its molar mass is equal to 36.458 g/mol. The physical properties of HCl depend on its concentration. Aluminium (Al) is a p-block element, showing properties similar to the silver metal.

HCl is one of the most important acids because it is used as a reagent in chemical laboratories. Al has the capability to react with acids as well as bases. In the following sections, we will study many facts based on HCl + Al reaction.

What is the product of HCl and Al?

When HCl is reacted with the element Al, the major product formed is Aluminium Chloride, and hydrogen gas is liberated in the process. The reaction can occur at room temperature. In other words, we can say that Al dissolves in hydrochloric acid.

6HCl(aq) + 2Al(s) → 2AlCl₃(aq) + 3H₂(g)

What type of reaction is HCl + Al?

The reaction between HCl and Al can be called a displacement reaction. We can see from the reaction that Chlorine detaches from the acid molecule and bonds with the Aluminium molecule. And Hydrogen in the reaction is released as a gas. It can also be referred to as a redox reaction.

How to balance HCl + Al?

We can balance the HCl + Al reaction easily by following the below steps:

HCl + Al → AlCl₃ + H₂

Step 1:

• Count the number of atoms on the reactant side and on the product side of each type.
•  Here we can see on the reactant side; we have one atom of Hydrogen, Chlorine and Aluminium each.
• On the product side, we have one atom of Aluminium, three atoms of Chlorine and two atoms of Hydrogen.

Step 2 :

• In this step, we will equalize the number of atoms of each type on both the sides.

6HCl + 2Al → 2AlCl₃ + 3H₂

HCl + Al titration

In order to determine the quantity of Aluminium, we can carry out titration between Aluminium and hydrochloric acid. In this titration, certain conditions are to be followed, which are discussed below.

Apparatus Required

50 mL burette, burette stand, Erlenmeyer flask, beakers, glass rods and volumetric flask.

Indicator

In the titration, phenolphthalein is used as the indicator, as it helps in figuring out when the titration reaches its endpoint (pink color in alkaline medium and turns colorless in acids).

Point to be noted

In the titration, HCl (of known concentration) is the titrant meaning it will be placed or added to the burette. Al is taken in the Erlenmeyer flask.

Procedure

• The apparatus should be cleaned and rinsed properly with the appropriate chemicals (in order to eliminate errors).
• The burette is filled with the HCl (should be standardized), and the Al solution is added to the Erlenmeyer flask.
• Indicator phenolphthalein is added (buffer solution added if required), and the solution is mixed properly.
• Titration should be carried out by releasing the acid from the burette in drop by drop manner until there is a change in color.
• Once the color is changed, the endpoint is reached.
• The titration should be repeated three times to get accurate results, and each time the reading is noted down.
• By using the formula N₁V₁ = N₂V₂, the volume of the required chemical is determined.

HCl + Al net ionic equation

The net ionic equation for the reaction between HCl and Al is discussed below:

• First, write down the balanced molecular reaction between HCl and Al, along with their states.

• 6HCl(aq) + 2Al(s) → 2AlCl₃(aq) + 3H₂(g)

• Write down the ionic equation (split the electrolytes into their respective ions.

• 6H⁺ + 6Cl^– + 2Al → 2Al₃⁺ + 6Cl^– + 3H₂

• Cancel out the similar terms on both the sides, and the remaining terms give us the required net ionic equation.

HCl + Al conjugate pairs

The conjugate acid of Aluminium salt and the respective conjugate base is the conjugate pair of the reaction between Al and HCl. It is indicated in the below equation.

HCl + Al = Cl^– + HAl⁺

HCl and Al intermolecular forces

The intermolecular force observed in HCl is ionic bonding. The Chlorine being charged negatively takes up the electron from the proton.

HCl + Al reaction enthalpy

The enthalpy of the reaction between HCl and Al is -1049 kJ/mol.

Is HCl + Al a buffer solution?

The reaction between HCl and Al will not form a buffer because the product formed is a metal salt and Al is amphoteric in nature.

Is HCl + Al a complete reaction?

The reaction between Al and HCl is a complete reaction as the only product formed is Aluminium Chloride (along with the liberation of H₂ gas).

Is HCl + Al an exothermic or endothermic reaction?

The reaction between Al and HCl is observed to be an exothermic reaction and is quite vigorous. Hence the reaction should be carried out away from fire as the H₂ generated in the reaction has the potential to combine with oxygen (atmospheric) and can explode.

Is HCl + Al a redox reaction?

The reaction between HCl and Al is a redox reaction. The oxidizer or the oxidizing agent in the reaction are the hydrogen ions from the acid molecule, and the Aluminium element is the reducing agent.

Is HCl + Al a precipitation reaction?

The reaction between HCl + Al is not a precipitation reaction as the metal Aluminium is seen to dissolve in HCl to give Aluminium Chloride and the gas liberated (H₂) is colorless. Also, the product formed AlCl₃ is soluble in H₂O.

Is HCl + Al reversible or irreversible reaction?

The reaction between HCl + Al is irreversible in nature because it is not possible for the products Aluminium Chloride and Hydrogen gas to react and give back the original form of the reactants.

Is HCl + Al displacement reaction?

A single displacement reaction takes place when HCl reacts with Al. The Aluminium element displaces the hydrogen atoms in the HCl molecule.

Conclusion

The reaction between HCl + Al is seen to be exothermic; hence one should be very careful while handling these reactions. Also, it is an irreversible and a single displacement type of reaction.