Question

Match the following physical and chemical properties with ethane, \(\mathrm{C}_{2} \mathrm{H}_{6}\), or sodium bromide, NaBr: a. boils at \(-89^{\circ} \mathrm{C}\) b. burns vigorously in air c. is a solid at \(250^{\circ} \mathrm{C}\) d. dissolves in water

Short answer

a. Ethane,b. Ethane,c. Sodium bromide,d. Sodium bromide.

Step-by-step solution

Identify Substance for Boiling Point

Compare the boiling points of ethane and sodium bromide. Ethane, \(\text{C}_2\text{H}_6\), is a gas at room temperature and boils at \-89^{\text{o}} \text{C}\. Sodium bromide, NaBr, is an ionic compound that has a much higher boiling point.

Identify Substance that Burns Vigorously

Determine which substance reacts with oxygen. Ethane, \(\text{C}_2\text{H}_6\), is a hydrocarbon and burns vigorously in air, while sodium bromide, NaBr, does not burn.

Identify Substance that is Solid at 250°C

Check the states of both substances at 250°C. Ethane, \(\text{C}_2\text{H}_6\), is a gas at this temperature. Sodium bromide, NaBr, remains a solid since it has a melting point much higher than 250°C.

Identify Substance that Dissolves in Water

Determine which substance is soluble in water. Sodium bromide, NaBr, is an ionic compound and dissolves well in water. Ethane, \(\text{C}_2\text{H}_6\), is nonpolar and does not dissolve in water.

Key concepts

boiling points of compounds

Understanding the boiling points of different compounds is crucial for identifying their physical properties. The boiling point of a compound is the temperature at which it transitions from a liquid to a gas. In our exercise, we have ethane \(\text{C}_2\text{H}_6\) and sodium bromide \(\text{NaBr}\). Ethane, being a simple hydrocarbon, boils at a very low temperature of \-89^{\text{o}} \text{C}. This makes it a gas at room temperature. On the other hand, sodium bromide, an ionic compound, has a much higher boiling point due to the strong electrostatic forces between its ions. Such understanding helps in associating ethane as having the property of boiling at \-89^{\text{o}} \text{C}. Ionic compounds like sodium bromide generally require much higher temperatures to boil.

reactivity with oxygen

Reactivity with oxygen is observed as a chemical property. Some substances react with oxygen, undergoing a chemical change, while others do not. Ethane \(\text{C}_2\text{H}_6\) is a hydrocarbon, and hydrocarbons typically burn in the presence of oxygen. This combustion reaction results in the production of carbon dioxide and water, releasing energy as heat. Due to this property, ethane burns vigorously in air. Sodium bromide \(\text{NaBr}\) does not share this characteristic. As an ionic compound, it does not readily burn in oxygen. It demonstrates how recognizing the reactivity of compounds with oxygen helps in classifying their chemical behaviors.

states of matter at various temperatures

Compounds can exist in different states of matter (solid, liquid, gas) at various temperatures. Ethane \(\text{C}_2\text{H}_6\), for example, is a gas at room temperature but will become a liquid if cooled to its boiling point of \-89^{\text{o}} \text{C}. At much higher temperatures, like 250°C, it will remain a gas. Sodium bromide \(\text{NaBr}\), however, is a solid at room temperature and remains a solid even at 250°C. Its melting point is substantially higher, indicating the strong ionic bonds that require greater heat energy to break. These properties are essential when distinguishing among compounds for various temperature conditions.

solubility of compounds in water

Solubility in water is a significant physical property that affects the utility and handling of compounds. Ionic compounds like sodium bromide \(\text{NaBr}\) are typically highly soluble in water. This happens because the positive and negative ions in sodium bromide interact strongly with water molecules, leading to dissolution. In our case, sodium bromide dissolves well in water, making it useful in various aqueous solutions. Conversely, ethane \(\text{C}_2\text{H}_6\), being nonpolar, does not dissolve in water. Nonpolar compounds generally do not mix with polar solvents like water, indicating vastly different solubility characteristics between ethane and sodium bromide.