Everyday Science: The Chemistry of Cleaning

by Christopher Gavigan
Tuesday, April 06, 2010

When you break it down, all of life is science. Whether you were good or bad at science in school, you use it every day. You reap the benefits of scientific ingenuity when you drive a car or visit the doctor’s office and you perform your own scientific experiments when you cook and clean.

I was reminded of this elemental reality upon touring the formulating and manufacturing facilities of Earth Friendly Products in Southern California (a cleaning products company dedicated to delivering neutral pH products). There we discussed some basic facts about pH, and how the pH of our homes, as well as the cells of our bodies, affect our overall state of health - either cleanliness or filth.

Here’s a quick everyday science lesson in understanding pH to make cleaning easier.

According to Wikipedia:

“In chemistry, pH (short for potentiometric hydrogen ion concentration) is a measure of the acidity or basicity of a solution. Pure water is said to be neutral, with a pH close to 7.0. Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are said to be basic or alkaline.”

The pH scale ranges from 0.0 to 14.0 and it’s important to understand that it’s a logarithmic scale. This means that a change of one pH unit indicates a ten-fold increase in the concentration of hydrogen ions. For example, if we begin with a solution that 
is pH 7 neutral, when the alkalinity of the solution is increased to 8, the strength is now
10 times stronger. Increase the pH to 9 and the solution is 100 times 
stronger than it was at 7. This rapid intensification continues 
until pH 14, which is 10 million times as alkaline as pH 7. It is the same going the other direction on the scale - a pH of 0 is 10 million times as acidic as pH of 7.

Human blood is very near to neutral (roughly 7.4) and human skin is a little more acidic to prevent bacterial growth (roughly 6.0). An infant’s skin is nearer to 7.4 and quickly decreases as they age to have the normal acidity for bacterial protection. You should be trying to use cleaners (and other products) that are close to your own pH. Anything too acidic or alkaline can be irritating or caustic and you’ll need to take precautions.

Note: the performance of a cleaning product cannot be determined simply by knowing the pH of the product. Just because a solution is more acidic or more alkaline does not mean it has superior cleaning capabilities. What really happens in cleaning is an attempt to "neutralize.”

Acids: Acids include coffee, cola, vinegar, and lemon juice. In cleaning products, acids help break down things like rust or mineral deposits. Some common cleaning products that have an acidic pH are: hard water/mineral deposit removers, toilet bowl cleaners, tub and tile cleaners, and mold solutions.

Bases: Bases include baking soda, Borax, ammonia and bleach. They’re useful for removing fatty and oily soils from surfaces. Some common cleaning products that have a basic pH include: oven cleaner, all purpose cleaners, and laundry detergents.

The pH of the stain you are attempting to remove combined with the type of the surface you are addressing should dictate the pH of the cleaner that you are using. Here are general recommendations based on an industry fact sheet on the chemistry of cleaning:

Choosing the right cleaner begins by analyzing the soil and matching it to the cleaner best designed to remove it. Some of the common forms of soil best removed by one of the basic cleaners are as follows:

Acids - mineral deposits, such as: iron, lime buildup, uric acid stains, rust, scale, water spots, soap deposits
Alkalis - most common forms of soil including dirt, soot, fats, cooking oils, food stains, baked on grease
Neutral - light-duty cleaning

Choosing the right cleaner also demands an analysis of the surface to be cleaned. The three basic cleaners are designed on different surface areas. The surfaces commonly cleaned by the basic cleaners are as follows:

Neutral - all water washable surfaces, floors coated with finish
Alkalis - resilient flooring metal, porcelain, china, fabrics, formica, vinyl, concrete, quarry tile, removing floor finish films
Acids - vitreous china, metal, glass cement, quarry tile, plexiglass, glass

Read More:

Chasing Molecules: Poisonous Products, Human Health, and the Promise of Green Chemistry

Image Courtesy of Wikimedia Commons.

from Healthy Child Healthy World : Know More. Worry Less. Live Better.


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