Question

Write a balanced equation describing the reaction of aluminum metal with concentrated aqueous sodium hydroxide.

Short answer

The balanced equation for the reaction of aluminum metal with concentrated aqueous sodium hydroxide is: \[ Al_{(s)} + 3NaOH_{(aq)} \rightarrow Al(OH)_{3_{(s)}} + 3Na_{(s)} \]

Step-by-step solution

Write the unbalanced equation

The unbalanced equation for the reaction between aluminum metal (Al) and concentrated aqueous sodium hydroxide (NaOH) is: \[ Al_{(s)} + NaOH_{(aq)} \rightarrow ? \]

Identify the products of the reaction

The reaction between aluminum metal and aqueous sodium hydroxide produces aluminum hydroxide (Al(OH)₃) and sodium metal (Na). The balanced equation should have the following form: \[ Al_{(s)} + NaOH_{(aq)} \rightarrow Al(OH)_{3_{(s)}} + Na_{(s)} \]

Balance the sodium atoms

We observe that there are currently different numbers of sodium atoms on both sides of the equation. To balance them, we place a "3" in front of the sodium hydroxide to make the number of sodium atoms equal on both sides: \[ Al_{(s)} + 3NaOH_{(aq)} \rightarrow Al(OH)_{3_{(s)}} + 3Na_{(s)} \]

Balance the hydrogen and oxygen atoms in the equation

The equation is now balanced for aluminum and sodium atoms, but not for hydrogen and oxygen. To balance the remaining atoms, we observe that there are three hydroxide groups (OH⁻) on each side of the equation already. Thus, the number of hydrogen and oxygen atoms are equal on both sides. The final balanced equation is: \[ Al_{(s)} + 3NaOH_{(aq)} \rightarrow Al(OH)_{3_{(s)}} + 3Na_{(s)} \]

Key concepts

Chemical Reaction

Understanding a chemical reaction begins with identifying the substances involved and the changes they undergo. In a chemical reaction, reactants transform into products through breaking and forming chemical bonds. This process involves the principles of the conservation of mass and energy.

For instance, when aluminum metal reacts with sodium hydroxide, a chemical reaction occurs where reactants (aluminum and sodium hydroxide) are converted into products (aluminum hydroxide and sodium metal). During this reaction, the properties of the end products are distinctly different from those of the original reactants. It's important to recognize that no matter the complexity of the reaction, the total mass of the reactants always equals the total mass of the products, affirming the law of conservation of mass.

Stoichiometry

Stoichiometry is a branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. One key aspect of stoichiometry entails balancing chemical equations, ensuring that the number of atoms for each element is conserved from reactants to products.

To illustrate, when balancing the equation for the aluminum reaction with sodium hydroxide, we systematically adjust the coefficients in front of each compound to ensure that the atoms are balanced on both sides. Stoichiometry is crucial not only for theoretical purposes but also for practical applications like predicting how much of each reactant is needed to produce a desired amount of product in a reaction.

Aluminum Reaction with Sodium Hydroxide

The reaction between aluminum metal and sodium hydroxide is a specific type of chemical process involving an aluminum and hydroxide ion. It’s an example of a single displacement reaction where aluminum metal displaces sodium ions in sodium hydroxide to form aluminum hydroxide and elemental sodium. When writing the balanced chemical equation, it’s vital to ensure that atoms of each element are equal on both sides of the equation.

In our example, balancing starts with the unbalanced equation and proceeds by comparing the number of atoms of each element on both sides, adjusting coefficients accordingly until the atoms are balanced. Such exercises highlight the reactivity of aluminum when in contact with a strong base like sodium hydroxide and the necessity to understand the stoichiometry to predict the outcome of the reaction accurately.