Physical Changes: Boiling — Reading Comprehension

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Grades

Standards

MS-PS1-4

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This comprehensive middle school science passage explores the concept of boiling as a physical change, aligned with NGSS standard MS-PS1-4. Students will learn about the mechanisms behind boiling, including energy absorption, bubble formation, and the constant temperature at the boiling point. The passage provides real-world examples such as boiling water for pasta and compares boiling points of different substances. It integrates key scientific vocabulary and explains how boiling connects to broader scientific principles, including phase changes and energy transfer. The associated activities support comprehension, analysis, and application, with quizzes, writing prompts, graphic organizers, and accessible Spanish translations. Audio integration makes the resource ideal for diverse learning settings. This passage is perfect for 6th to 8th graders seeking a deeper understanding of the science of boiling.

CONTENT PREVIEW

boiling-1 — Water boiling at 100°C (212°F)

Boiling is a fundamental physical change where a liquid transforms into a gas, not just at the surface but throughout the entire liquid. In science, understanding boiling helps explain how substances behave under heat and how energy moves in a system. The boiling of water is a central process in cooking, industry, and nature, making it a key concept in physical science. Scientists observe boiling to investigate the interactions between energy, particles, and states of matter.

Mechanism of Boiling: Energy and Particle Interactions

When a liquid is heated, its particles gain energy and move more rapidly. At a substance's boiling point, enough energy is absorbed that particles throughout the liquid can break free from the liquid's structure and become gas. This process is called vaporization. Unlike evaporation, which happens only at the surface, boiling creates bubbles of gas within the liquid. These bubbles rise to the surface and burst, releasing gas. Importantly, during boiling, the temperature remains constant at the boiling point. All added energy goes into changing the state, not increasing the temperature. For water, this happens at 100°C (212°F) at sea level.

Boiling in Everyday Life and Science

Boiling is observed when preparing foods like pasta, when water is heated until it bubbles vigorously. Other substances boil at different temperatures—ethanol boils at 78°C while liquid nitrogen boils at -196°C. Scientists use boiling points to help identify substances and design processes such as distillation, where mixtures are separated by their boiling points. Boiling also plays a critical role in sterilizing water to kill bacteria, underlining its importance in public health. The boiling process demonstrates the conservation of energy and the predictable nature of phase changes.

Complexities and Broader Implications

Boiling is affected by pressure. At higher altitudes, such as in mountains, water boils below 100°C due to lower air pressure. This means cooking times must be adjusted. Understanding boiling is vital in many industries, from food production to chemical engineering. The study of boiling connects to broader principles like the kinetic molecular theory and the conservation of matter and energy, helping us make sense of physical changes in our world.

Boiling is more than just bubbles; it is a window into energy, particle motion, and the laws that govern matter.

Interesting Fact:
At the top of Mount Everest, water boils at about 70°C (158°F)—far below the typical boiling point at sea level!

What is the main difference between boiling and evaporation?

Boiling occurs throughout the liquid, while evaporation happens only at the surface.Evaporation happens faster than boiling.Boiling cools a liquid, but evaporation heats it.Evaporation forms bubbles inside the liquid.

At what temperature does water boil at sea level?

100°C (212°F)78°C (172°F)0°C (32°F)-196°C (-321°F)

What happens to the temperature of a liquid during boiling?

It remains constant at the boiling point.It keeps increasing.It decreases.It becomes unpredictable.

Why do scientists use boiling points?

To identify substances and separate mixtures.To change the color of liquids.To cool down substances quickly.To measure the volume of gases.

Which of these is an example of a substance with a very low boiling point?

Liquid nitrogenEthanolWaterOlive oil

What role does pressure play in boiling?

Lower pressure reduces the boiling point of a liquid.Higher pressure makes boiling impossible.Pressure does not affect boiling.Pressure only affects solids.

What is the process called when particles in a liquid gain enough energy to become gas?

VaporizationCondensationSublimationMelting

Which of the following is TRUE about boiling?

Boiling demonstrates the conservation of energy.Boiling destroys energy.

Boiling is a physical change that alters the chemical identity of a substance. (True/False)

FalseTrue

The kinetic molecular theory helps explain boiling by describing how particles move and gain energy. (True/False)

TrueFalse