Final answer:
Pyrex® is preferred for laboratory and household use due to its low coefficient of linear expansion, which makes it less prone to breaking from thermal stress. Clear, round Pyrex® glass can be used to effectively cover an evaporating dish in the lab, providing durability and reliability under varying temperatures.
Step-by-step explanation:
When using glassware in a laboratory setting, it's essential to choose materials that can withstand thermal stress. Pyrex®, a type of glass commonly found in both labware and household cookware, is preferred for its durability under thermal conditions. This is due to its low coefficient of linear expansion, which means it doesn't expand or contract as much as other types of glass when exposed to temperature changes. This property makes Pyrex® less susceptible to breaking from thermal stress, such as when transitioning from hot to cold temperatures quickly.
For instance, when you need to cover an evaporating dish to prevent the escape of substances or to maintain a controlled environment within the dish, using a clear, round glass like Pyrex® works well. In science classes, an example of this application is when iodine crystals on a hot plate transition directly from a solid to a gas—a process known as sublimation—and the gaseous iodine then deposits on an ice-cold watch glass.
Understanding the properties of materials like Pyrex® is crucial in fields such as Chemistry, where the thermal expansion of solids and liquids is a fundamental concept. Uneven cooling leading to thermal stress is a common problem that can cause breakage. However, materials with a low coefficient of linear expansion, such as Pyrex®, are engineered to minimise these risks, making them invaluable for both laboratory and culinary applications.