Question

What is a gas-evolution reaction? Give an example.

Short answer

A gas-evolution reaction is a chemical reaction where one of the products is a gas, such as the reaction of sodium bicarbonate with acetic acid to produce carbon dioxide.

Step-by-step solution

Define Gas-Evolution Reaction

A gas-evolution reaction is a type of chemical reaction in which one of the products is a gas. These reactions often occur in aqueous solutions and involve the liberation of a gas as a result of the reaction between the reactants.

Provide an Example

One common example of a gas-evolution reaction is the reaction between sodium bicarbonate (baking soda) and acetic acid (found in vinegar). When these two substances mix, carbon dioxide gas is produced along with water and sodium acetate. The chemical equation for this reaction is: \[\text{NaHCO}_3(aq) + \text{CH}_3\text{COOH}(aq) \rightarrow \text{CO}_2(g) + \text{H}_2\text{O}(l) + \text{NaCH}_3\text{COO}(aq)\]

Key concepts

Understanding Chemical Reactions

A chemical reaction is a process where substances, known as reactants, transform into different substances called products. These transformations occur as a result of the breaking and forming of chemical bonds, which involves changes in the arrangement of electrons around atoms. For a reaction to take place, reactants must collide with sufficient energy and an appropriate orientation.

In educational contexts, understanding chemical reactions is fundamental because it's the basis of chemistry and a frequent topic in science curricula. It's essential to grasp that during a chemical reaction, matter is neither created nor destroyed, which is articulated by the Law of Conservation of Mass. Reactions can be classified into several types, such as synthesis, decomposition, single replacement, and double replacement. Among these, a particular interesting type is the gas-evolution reaction, where a gas is produced as a product, offering visible evidence of the reaction occurring.

The Reaction of Sodium Bicarbonate and Acetic Acid

One common household example of a gas-evolution reaction is the interaction between sodium bicarbonate (baking soda) and acetic acid (the main component of vinegar). This reaction is not only a popular science fair project but also illustrates key concepts in chemistry.

Sodium bicarbonate acts as a base, and acetic acid is an acid. When they react, they neutralize each other, resulting in the formation of carbon dioxide gas, water, and a salt (sodium acetate). The carbon dioxide gas produced can cause fizzing or bubbling, a hallmark characteristic of gas-evolution reactions. This reaction is also an example of an acid-base reaction and can be utilized to discuss topics such as reaction rates, the pH scale, and the role of catalysts in chemical reactions. The practical applications for this reaction are diverse, from culinary uses in baking to educational demonstrations.

Deciphering Chemical Equations

Chemical equations are symbolic representations of chemical reactions, and they serve as a shorthand method to convey detailed information about the processes involved. A well-written chemical equation provides insights into the quantities of reactants and products, their physical states, and the direction of the reaction.

The equation for the reaction between sodium bicarbonate and acetic acid, for example, clearly shows the reactants and products, as well as their states: aqueous (aq), liquid (l), and gas (g). Learning to balance chemical equations is a core skill in chemistry, as it demonstrates the application of the Law of Conservation of Mass in a practical setting. It's crucial to remember that the coefficients in a chemical equation indicate the proportions of substances involved but do not affect the actual identity of the substances. Being able to write and interpret these equations is vital for students' success in both academic pursuits and in many industry-related applications.