Forces within Liquids

Front

Cohesive Forces Noun

---

[koh-hee-siv for-sez]

Back

Cohesive Forces

---

The forces of attraction that like particles exert on one another, holding the substance together and causing surface tension.

---

Example: Water molecules attract each other, which are cohesive forces. A molecule inside the droplet is pulled equally, while a surface molecule is pulled inward.

Front

Surface Tension Noun

---

[sur-fis ten-shun]

Back

Surface Tension

---

The tendency of a liquid's surface to contract to the smallest possible area due to cohesive forces among its particles.

---

Example: This diagram shows that liquid molecules inside are pulled equally in all directions, but molecules at the surface are pulled only inwards, creating a strong, tight layer.

Front

Viscosity Noun

---

[vis-kos-i-tee]

Back

Viscosity

---

A measure of a fluid's internal friction or resistance to flow, which is caused by its cohesive forces.

---

Example: This image compares water and honey being poured to show that honey, with high viscosity, flows slower than water, which has low viscosity.

Front

Adhesive Forces Noun

---

[ad-hee-siv for-sez]

Back

Adhesive Forces

---

The attractive forces that act between particles of different substances, causing them to cling to each other.

---

Example: The image shows that adhesive forces, the attraction between different substances, cause water to 'climb' the sides of a glass tube, creating a concave meniscus.

Front

Capillary Action Noun

---

[kap-uh-ler-ee ak-shun]

Back

Capillary Action

---

The phenomenon where a liquid rises inside a narrow tube because adhesive forces are stronger than cohesive forces.

---

Example: Water moves up a plant's stem because of two forces: cohesion, where water molecules stick together, and adhesion, where water molecules stick to the stem walls.

Front

Evaporation Noun

---

[ih-vap-uh-rey-shun]

Back

Evaporation

---

The process of a liquid changing to a gas as energetic particles break through the surface layer and escape.

---

Example: This diagram shows heat from the sun causing water from the ocean to turn into vapor and rise into the air, which is the process of evaporation.

Front

Volatile Adjective

---

[vol-uh-til]

Back

Volatile

---

Describing a liquid that evaporates quickly at room temperature due to having weak cohesive forces between its particles.

---

Example: This animation compares a volatile liquid (left), where particles easily escape into a gas, to a non-volatile liquid (right), where particles remain contained.

Front

Condensation Noun

---

[kon-den-sey-shun]

Back

Condensation

---

The process where particles of a gas return to the liquid phase as their kinetic energy or temperature decreases.

---

Example: Warm, moist air cools when it touches a cold surface, causing the water vapor (gas) in the air to turn into liquid water droplets.

Front

Water Vapor Noun

---

[waw-ter vey-per]

Back

Water Vapor

---

The gaseous phase of water that is formed when liquid water evaporates and enters the surrounding air.

---

Example: Heating liquid water gives its molecules enough energy to escape into the air as a gas, which is called water vapor.

Front

Fog Noun

---

[fog]

Back

Fog

---

A visible cloud of tiny condensed water droplets suspended in the atmosphere at or near the Earth's surface.

---

Example: This diagram shows how fog, a cloud of tiny liquid water droplets, forms near the ground when warm, moist air cools as it moves over cold air.