Explain why sugar will dissolve on its own in a cup of cold water if we leave it for long enough.
The Correct Answer and Explanation is:
Sugar dissolves in water due to a process known as dissolution, which is driven by the interaction between the sugar molecules and the water molecules. While this process is faster in warmer water, it will still occur in cold water, albeit more slowly.
Water is a polar solvent, meaning its molecules have a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom. Sugar (specifically sucrose) is also polar, with hydroxyl groups (-OH) that can form hydrogen bonds with the water molecules. When sugar is added to water, the water molecules surround the sugar molecules and pull them apart, breaking the bonds between the sugar molecules. This occurs because the positive part of the water molecules (hydrogen) is attracted to the oxygen in the sugar, while the negative part of the water molecules (oxygen) is attracted to the hydrogen in the sugar.
At room temperature or in colder water, the kinetic energy of the water molecules is lower compared to warmer temperatures. This means the water molecules move slower, which results in the sugar molecules being broken apart more gradually. The dissolution process continues over time as the sugar molecules spread out and interact with water molecules, eventually dispersing evenly throughout the water. This is why, even in cold water, sugar will eventually dissolve if left long enough.
However, the rate of dissolution is influenced by factors such as temperature, stirring, and the surface area of the sugar. Warmer water provides more kinetic energy to the water molecules, leading to faster dissolution. Stirring increases the interaction between sugar and water molecules, while smaller sugar particles have a larger surface area, also accelerating the dissolution process. Thus, while sugar dissolves in cold water eventually, it dissolves more quickly in warmer water.