Question

You have two glass bottles, one containing oxygen and one filled with nitrogen. How could you determine which one is which? [Sections \(22.5\) and \(22.7\) ]

Short answer

To determine which glass bottle contains oxygen and which one contains nitrogen, perform two tests: the ignition test and the glowing ember test. Ignite a small piece of wood and hold it near the opening of the first bottle, observing any changes in the flame's intensity. Then, hold a glowing ember near the opening and observe any changes in its brightness. Repeat these tests with the second bottle. If the flame intensifies or the ember glows more brightly, the bottle likely contains oxygen. If the flame is extinguished or shows no significant change, or if the ember's brightness remains unchanged, the bottle likely contains nitrogen.

Step-by-step solution

Gather necessary materials

Prepare the following items: 1. A small piece of wood or a wooden splinter. 2. A burning or glowing ember (a glowing piece of wood from a fire, for example).

Test the reactivity of the gases

Open the first glass bottle, and do the following tests: Test A: Ignition test 1. Hold the small piece of wood or splinter near the opening of the bottle. 2. Ignite the wood with a lighter or match. 3. Observe if the flame is extinguished or it burns more vigorously. Test B: Glowing ember test 1. Hold a burning or glowing ember near the opening of the bottle. 2. Observe if the ember glows more brightly or if there is no change. After performing these tests, repeat them for the second glass bottle.

Analyze the results

Based on the results of the tests, we can determine which bottle contains oxygen and which one contains nitrogen: - If the flame in Test A burns more vigorously or if the ember in Test B glows more brightly when exposed to the gas in a bottle, then that bottle likely contains oxygen. This is because oxygen supports combustion, which makes the flame or ember burn more intensely. - If the flame in Test A is extinguished or shows no significant change, or if the ember in Test B shows no significant change when exposed to the gas in a bottle, then that bottle likely contains nitrogen. Nitrogen, being relatively inert, will not support combustion and should not cause any noticeable change in the flame or ember's intensity.

Key concepts

Reactivity of Gases

Gases exhibit different levels of reactivity due to their varying chemical properties. Reactivity refers to the tendency of a chemical species to engage in a reaction.

To demonstrate reactivity, a common experiment is observing the behavior of gases when in contact with a flame. For instance, introducing a wooden splinter to different gaseous environments can yield insightful results. A gas that enhances the burning of the splinter is considered reactive, whereas a gas that extinguishes or does not affect the flame indicates low reactivity or inertness.

• Oxygen is a highly reactive gas that readily participates in combustion reactions.
• Nitrogen, on the other hand, is mostly inert under standard conditions; it does not readily react with other substances.

This contrast in reactivity is why a flame test can effectively differentiate between oxygen and nitrogen. An enhanced flame suggests the presence of oxygen, which is essential for the process known as combustion.

Oxygen and Combustion

Oxygen, a key element necessary for the process of combustion, reacts with a fuel source and an ignition temperature to produce fire. The presence of oxygen turns a small spark into a vigorous flame due to its role as an oxidizing agent—a substance that accepts electrons from a fuel.

Demonstrations of this concept often include a glowing ember test. A glowing ember, when introduced to an oxygen-rich environment, will typically glow brighter and burn hotter, showcasing oxygen's significant role in supporting and intensifying combustion.

• Combustion requires three components: a fuel source, an ignition point, and oxygen.
• Oxygen allows for the release of energy from the fuel source in the form of heat and light.
• The absence of oxygen results in the cessation of the combustion process, as seen when a flame goes out.

Understanding the relationship between oxygen and combustion is fundamental in fields ranging from firefighting to engineering, as it allows for the manipulation and control of fire for various applications.

Chemical Properties of Nitrogen

Nitrogen is an essential element found abundantly in Earth's atmosphere, accounting for approximately 78% of the atmospheric volume. Despite its prevalence, nitrogen is chemically inert under normal conditions due to its strong triple bond (N≡N) which is difficult to break at room temperature.

Because of its chemical inertness, nitrogen does not support combustion and, therefore, is often used in industry to create inert atmospheres where oxidation is undesirable. This property makes nitrogen a suitable candidate for the preservation of perishable items and the production of electronics.

• Nitrogen is inert and does not easily engage in chemical reactions at standard temperature and pressure.
• The strong triple bond in molecular nitrogen (N2) gives it stability, preventing it from supporting combustion.
• Despite being unreactive, nitrogen is a crucial component for all life on Earth, as it forms a part of amino acids, proteins, and nucleic acids.

Understanding nitrogen's chemical properties helps in both its industrial application and the management of fire safety procedures, as it can act as a fire suppressant by displacing oxygen in an environment.