Classification of Matter

Applying Classification of Matter

On May 19, 2015, an oil pipeline ruptured in the Pacific Ocean near Santa Barbara, California. The sudden rupture caused crude oil to gush into areas of water nearby. The oil floated to the surface of the water and spread outward in all directions. The feathers of seabirds that came in contact with the enormous oil slick became coated with the dark goo, causing the feathers to mat, separate, become unaligned, and fail to perform certain vital functions.

These functions included the ability of the seabirds to maintain sufficient insulation against cold and hot temperatures, waterproofing their bodies, and flying. A breakdown in any of these functions threatens the survival of seabirds. Seabirds respond to these hazards by preening, or cleaning their feathers with their beaks. However, this behavior causes the birds to ingest oil, which can subsequently damage internal organs, resulting in death.

As a consequence, one of the primary responsibilities of volunteers who rush to the scene of a marine oil spill is to remove oil from affected seabirds. Since oil does not dissolve in water, water itself cannot be used to remove the oil that adheres to the feathers of the birds. However, water can wash away oil from feathers if a detergent is used at the same time. The detergent is an emulsifying agent. When applied to oil and water, it transforms the mixtureglossary term (opens in a new window) into a colloidglossary term (opens in a new window) called an emulsionglossary term (opens in a new window).

As anyone who has used a detergent to clean a greasy container or dish understands, plain water will not achieve the desired result, but a combination of a detergent and water is effective. How do detergents help wash away grease, fat, or oil? The answer lies in the chemical structure and properties of detergents.

Detergents consist of large molecules. One end of the molecule possesses a partial electric charge. This end is called hydrophilic. Hydrophilic means "water loving," or being attracted to water. The polar character of a water molecule makes water especially effective at dissolving other charged molecules and ions.

The other end of the detergent molecule is not electrically charged. Stated another way, this end somewhat resembles the structure of oil particles. The electrically neutral end of a detergent molecule is attracted to particles of oil, but not to molecules of water. For this reason, the neutral end of the detergent molecule is called hydrophobic. Hydrophobic means "water hating," or not attracted to water.

When the oil on bird feathers is treated with a mixture of water and a mild detergent, the hydrophilic ends of the detergent molecules "stick" to water molecules. At the same time, the hydrophobic ends of the detergent molecules "stick" to oil particles. The detergent, oil, and water produce a mixture called a emulsion. This suspensionglossary term (opens in a new window) can be rinsed off of the feathers with additional water.

The cleaned birds are then usually confined to an enclosure where their feathers are dried with blowers commonly used on pets. During the drying procedure, the birds preen their feathers. Once realigned by preening, the feathers again provide insulation and waterproofing, and the birds are released.

STEM and Classification of Matter

The substances in most containers of the milk people purchase today are evenly distributed throughout the liquidglossary term (opens in a new window), and they do not separate out on standing. In other words, the substances in the container produce a colloid.

However, this description does not apply to the milk that comes directly from a cow. Raw milk, the milk that comes out of a cow, does not produce a colloid. If allowed to stand, the substances in raw milk will separate. Large fat globules, which are the primary components of cream, will float to the top, leaving behind a more watery liquid. This indicates that raw milk is a suspension.

For a number of reasons, milk producers (human farmers and manufacturers, not the cows) and milk consumers prefer milk that does not separate. In other words, they desire milk as a colloid, not a suspension. This desire led to the development of a technology that transforms the milk suspension into milk as a colloid.

A food scientist is someone who uses chemistry to study, analyze, and improve the methods by which food is created and processed. In this situation, the technology that is used is called homogenization, and the product is called homogenized milk. The following description explains how this technology works.

First, remember that an important distinction between a suspension and a colloid is particle size. The particles in a suspension are larger than the particles in a colloid. This difference indicates how raw milk might be homogenized by breaking large fat globules into much smaller fat globules.

The original patent for a machine able to homogenize milk was granted to French inventor Auguste Gaulin in 1899. Although the machine has been improved during the past century, its basic principles have remained unchanged. Milk is forced through very narrow tubes at high pressure and high velocity (up to 120 meters/second). During this process, the average diameter of fat globules may be reduced by a factor of about eight. At this reduction in diameter the fat globules become evenly dispersed and do not separate from the mixture.

Cleaning an Oil Spill

One of the jobs of environmental engineers is to test and evaluate methods of cleaning up oil spills. Part of this job includes cleaning the oil from bird feathers. Work with a partner to research different methods of cleaning up oil from feathers. Methods that you might consider are dispersants (detergents), absorption (cloth), and skimming with a spoon.