Question

Challenge When benzoic acid \(\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH}\right)\) and magnesium hydroxide are mixed, water and magnesium benzoate are produced.

Short answer

When benzoic acid \(\left(\mathrm{C}_{6} \mathrm{H}_{5}\mathrm{COOH}\right)\) and magnesium hydroxide are mixed, the balanced chemical equation for the double displacement reaction is: \(2 \mathrm{C}_{6} \mathrm{H}_{5}\mathrm{COOH} + \mathrm{Mg}\left(\mathrm{OH}\right)_{2} \rightarrow 2 \mathrm{H}_{2}\mathrm{O} + \mathrm{Mg}\left(\mathrm{C}_{6}\mathrm{H}_{5}\mathrm{COO}\right)_{2}\) This reaction results in the production of water and magnesium benzoate.

Step-by-step solution

Write down the reaction

Write the chemical reaction between benzoic acid (C6H5COOH) and magnesium hydroxide (Mg(OH)2) and indicate the products formed. C6H5COOH + Mg(OH)2 -> H2O + Magnesium Benzoate

Find the formula for Magnesium Benzoate

Magnesium benzoate is formed by replacing the hydrogen in benzoic acid with magnesium. The formula for magnesium benzoate can be obtained by writing the ions involved. Magnesium has a 2+ charge, while benzoic acid has a 1- charge. Mg2+ + 2 C6H5COO- -> Mg(C6H5COO)2 Now the chemical equation becomes: C6H5COOH + Mg(OH)2 -> H2O + Mg(C6H5COO)2

Balance the equation

Make sure that the number of each atom is the same on both sides of the equation. 2 C6H5COOH + Mg(OH)2 -> 2 H2O + Mg(C6H5COO)2 Now our balanced chemical equation is: 2 C6H5COOH + Mg(OH)2 -> 2 H2O + Mg(C6H5COO)2 This reaction is a double displacement reaction where magnesium hydroxide reacts with benzoic acid to form water and magnesium benzoate.

Key concepts

Double Displacement Reaction

A double displacement reaction, also known as a metathesis reaction, takes place when the ions of two compounds exchange places in an aqueous solution to form two new compounds. For example, when you mix benzoic acid ((C6H5COOH)) with magnesium hydroxide ((Mg(OH)2)), a double displacement reaction occurs. Here, the magnesium ion ((Mg^2+)) swaps places with the hydrogen ion ((H+)) from the benzoic acid, resulting in the formation of water ((H2O)) and magnesium benzoate ((Mg(C6H5COO)2)).

It’s essential to identify the type of reaction because it helps us predict the products and understand the reaction's mechanism. In the classroom or lab setting, recognizing a double displacement reaction can be an exciting challenge, as these reactions often result in a precipitate, a gas, or a molecular compound like water, which can be visually observed.

Chemical Reaction

A chemical reaction is a process in which one or more substances, known as reactants, are converted into one or more different substances, known as products. During a chemical reaction, the molecules' bonds are broken and reformed, leading to chemical changes. The reaction depicted in the exercise is a typical chemical reaction where benzoic acid reacts with magnesium hydroxide to yield water and magnesium benzoate.

Understanding chemical reactions is fundamental in chemistry as they form the basis of numerous scientific and industrial processes. For instance, the reaction between benzoic acid and magnesium hydroxide is not only an academic exercise but can also have practical applications in fields like pharmaceuticals and materials science where benzoate compounds are relevant.

Stoichiometry

Stoichiometry refers to the calculation of reactants and products in chemical reactions. In the given problem, balancing the chemical equation is a stoichiometry application. To comply with the law of conservation of mass, the equation must have the same number of atoms of each element on both sides of the reaction. By correctly balancing the equation (2 C6H5COOH + Mg(OH)2 -> 2 H2O + Mg(C6H5COO)2), we ensure that the number of hydrogen, carbon, oxygen, and magnesium atoms remains equal before and after the reaction.

Stoichiometry isn't just about balancing equations; it's about understanding the quantitative relationship between the reactants and products in a chemical reaction. This knowledge allows scientists to predict yields, calculate material needs for reactions, and scale up for production. It is a crucial skill for chemistry students as it interconnects scientific concepts and practical application.