Problem 75 - Chemistry

Question

Of the 90 or so naturally occurring elements, only four are liquid near room temperature: mercury (melting point = \(\left.-38.87^{\circ} \mathrm{C}\right)\), bromine \(\left(\right.\) melting point \(\left.=-7.2{ }^{\circ} \mathrm{C}\right)\), cesium (melting point \(\left.=28.40^{\circ} \mathrm{C}\right)\), and gallium (melting point \(=\) \(\left.29.78{ }^{\circ} \mathrm{C}\right)\). Convert these melting points to degrees Fahrenheit.

Step-by-Step Solution

Answer

Mercury: -37.97°F, Bromine: 19.04°F, Cesium: 83.12°F, Gallium: 85.60°F.

Step 1: Understand the conversion formula

To convert from Celsius (\(^\circ\)C) to Fahrenheit (\(^\circ\)F), you use the formula: \( F = \frac{9}{5}C + 32 \). Here, \(C\) represents the temperature in Celsius, and \(F\) will be the temperature in Fahrenheit upon performing the conversion.

Step 2: Convert mercury's melting point

Mercury's melting point is \(-38.87^\circ\)C. Using the formula \( F = \frac{9}{5}C + 32 \), substitute \(C = -38.87\):\[F = \frac{9}{5}(-38.87) + 32 = -37.966 + 32 \approx -37.97^\circ\text{F}\]

Step 3: Convert bromine's melting point

Bromine's melting point is \(-7.2^\circ\)C. Substitute \(C = -7.2\) into the formula:\[F = \frac{9}{5}(-7.2) + 32 = -12.96 + 32 = 19.04^\circ\text{F}\]

Step 4: Convert cesium's melting point

Cesium's melting point is \(28.40^\circ\)C. Substitute \(C = 28.40\) into the formula:\[F = \frac{9}{5}(28.40) + 32 = 51.12 + 32 = 83.12^\circ\text{F}\]

Step 5: Convert gallium's melting point

Gallium's melting point is \(29.78^\circ\)C. Substitute \(C = 29.78\) into the formula:\[F = \frac{9}{5}(29.78) + 32 = 53.604 + 32 \approx 85.60^\circ\text{F}\]

Key Concepts

Celsius to Fahrenheit Conversion

The conversion between Celsius and Fahrenheit is a fundamental concept, especially in chemistry, where temperature plays a key role in understanding chemical reactions and properties. The formula to convert a temperature from Celsius to Fahrenheit is simple:

• Start with your temperature in degrees Celsius (C).
• Multiply this value by \(\frac{9}{5}\) to convert the scale from base 100 of Celsius to base 180 of Fahrenheit.
• Finally, add 32 to shift the starting point from 0 in Celsius to 32 in Fahrenheit.

In formula terms: \[ F = \frac{9}{5} \times C + 32 \]
For example, if you have C = 29.78 degrees Celsius, multiplying it by \(\frac{9}{5}\) gives 53.604, and after adding 32, results in approximately 85.60\text{°F}.
Remember, understanding this conversion helps provide insight into environmental and experimental conditions across different regions.

Melting Points of Elements

Melting points are crucial to identifying the physical state of elements at given temperatures. Only a handful of elements are liquid near room temperature, making them unique among the approximately 90 naturally occurring elements. This state is determined by an element's melting point, the temperature at which it transitions from solid to liquid.
Consider these four elements, known for their interesting melting points:

• Mercury: Has a melting point of \(-38.87\text{°C}\), making it one of the few elements that is in liquid form at room temperature.
• Bromine: With a melting point of \(-7.2\text{°C}\), it remains a liquid under most conditions you encounter daily.
• Cesium: Its melting point of \(28.40\text{°C}\) means it's very close to room temperature, often requiring just a slight increase in ambient temperature to become liquid.
• Gallium: Melts at \(29.78\text{°C}\), and can literally melt in the palm of your hand.

Understanding the melting points of elements assists in making predictions about their behaviors in various environments.

Properties of Elements

Elements have distinct properties that define their character and use in applications, such as their melting points. These properties can broadly fall into several categories:

• Physical Properties: Include melting point, boiling point, density, and metal or non-metal status. They depict an element's state and usability.
• Chemical Properties: Describe how an element interacts with other substances. For example, reactivity with acids or oxygen can range from mild to highly reactive.
• Thermal Properties: Describe how an element behaves when exposed to temperature changes. Knowing boiling and melting points helps control conditions in various chemical processes.

Each element’s properties lead to its particular usage across different industries. For instance, mercury's unique liquid state makes it suitable for thermometers, whereas gallium's relatively low melting point finds use in specialized electronics.

Chemistry Education

Chemistry education involves understanding fundamental concepts that uncover how elements and compounds interact. It's not just the memorization of formulas or reaction sequences but also the ability to apply these concepts to real-life scenarios.
Effective learning strategies include:

• Practical Application: Engage with real-world problems and use experimental setups to see chemistry in action.
• Visualization: Utilize diagrams and molecular models to understand abstract concepts better.
• Problem Solving: Work through exercises to deepen understanding and hone calculation skills like converting temperatures.

Building a solid foundation in chemistry is essential for those who wish to pursue science-related fields or simply understand the world around them more comprehensively.