Understanding Acids

A warning about acids

Acids are on the lower number of the pH scale, when they come into contact with metal they produce hydrogen gas, which will harm your respiratory system. Of all the chemicals used in the detail business, wheel acids are the most dangerous to the wheel, the employee and the environment. Many contain hydrofluoric (HF) acid which is extremely harmful if you get it on your skin, in your eyes or inhale it and is not recommended.

With any wheel acid, you should always wear safety equipment. This means glasses and gloves; and the work should be done in a well-ventilated area.

Non-acid wheel cleaners, while not as dangerous, have a high pH (12 or 13). They are harmful to your eyes and will severely dry out your hands if not used with gloves. So do not be fooled into thinking that they are not dangerous. They will also etch a paint surface just like an acid

Also, repeated use of wheel acid can break down in the resin in the clear-coat and cause it to cloud and/or deteriorate. So use acid only when absolutely necessary. A high alkaline or an acidic cleaner may cause damage to the surface finis, especially if used on a hot wheel surface

And remember: Just because it cleans faster than non-acid does not mean you should always use it.

Catalyst

A catalyst works by lowering the activation energy for a reaction, thus dramatically increasing the rate of the reaction. As a result, products are formed faster and reactions reach their equilibrium state more rapidly. Most reaction rates are millions of times faster than those of comparable un-catalysed reactions. A catalyst is not consumed by the reactions they catalyse, nor do they alter the equilibrium of these reactions.

Reactivity

[: the rate at which a chemical substance tends to undergo a chemical reaction]

Like any chemical attacking a surface, temperature will dictate reactivity (acceleration of a chemical reaction [reagents - moisture and heat]. The more heat and moisture that is present (in the form of high humidity, dew and etc.) the more aggressive the acid becomes.

Then you have; an acid + water +oxygen + ozone all of which forms an acidic oxygen molecule that causes a concave indentation (acid etching) to the paint surface it should be noted that until this acid is neutralised subsequent moisture and heat will reactivate the acid and allow further damage, as acid requires an alkaline to neutralize it

Dilution

A water molecule is made from three parts: two hydrogen nuclei joined to an oxygen nucleus. Electrons surround the molecule, which has no overall charge. Water has the ability to act as both an acid and a base, and ionize other substances. It can also ionize itself, turning itself into an acid or a base. The ability of a substance to act as either an acid or a base is known as amphoteric.

pH is actually base 10 logarithmic scale so for every 10x dilution, it changes by 1 point and 100x dilution will change it by 2 points toward neutral pH (7.0). Once pH 7.0 is reached, additional dilution will not change it anymore.

A hydrogen ion is a single hydrogen nucleus with a positive charge (it is missing one electron). Acids are substances which ionize in water, producing a surplus of hydrogen ions. The more of these ions that are produced, the more acidic the solution, and the lower the pH

A hydroxide ion is the part of the water molecule that is left when a hydrogen ion is removed. Hydroxide ions have an extra electron, and so are negatively charged. Bases are substances which increase the numbers of hydroxide ions, and thus remove hydrogen ions. By reducing the concentration of hydrogen atoms, bases raise the pH.

There are several things one has to remember when working with substances such as sodium hydroxide, a strong base whose chemical formula is written as NaOH. This alkaline is famous in industries due to its pH control purposes, being able to neutralize acids and acidic oxides with great efficiency. Lye or caustic soda, as it is commonly known, is used in manufacture of soaps and detergents, as well as many cleaning liquids. It is also found in processing of cotton, metals like aluminium, textile, paper, and pulp. This ionic compound dissociates completely into sodium ions and hydroxide ions in aqueous solutions.

Since it forms extremely exothermic solutions with water, it also reacts with amphoteric transition metals like aluminium, tin and zinc. Typical reactions of sodium hydroxide with metals like the ones mentioned liberated hydrogen gas, which ignites in the presence of oxygen.

When water is added to an alkaline solution the OH-ions will be reduced; since OH- ions are what gives an alkaline its pH. Water is neutral, which means it has an even amount of OH- and H+ ions. So when you add water you are diluting the alkaline, by lowering the concentration of OH- ions. When an acid is poured into water, it gives up H+ ions (hydrogen) to the water. When a base is poured into water, it gives up OH- ions (hydroxide) to the water.

Water

Water is the chemical substance with chemical formula H2O: one molecule of water has two hydrogen atoms covalently bonded to a single oxygen atom. It’s often referred to as the universal solvent. Substances that dissolve in water are known as hydrophilic (water-loving) substances, while those that do not mix well with water (e.g., fats and oils), are known as hydrophobic (water-fearing) substances.

a)        Potable water - usually contains a number of microscopic contaminants (turbidity) along with dissolved minerals such as calcium and iron.

Distilled water should ideally be nothing but hydrogen and oxygen molecules and has virtually all of its impurities removed through distillation, which involves boiling the water and re-condensing the steam into a clean container (pH 6.0 – 7.5)

b)       Distilled water - In chemical and biological laboratories distilled water is used, as it has many of its impurities removed through a distillation process [: involves boiling the water and then condensing the steam into a clean container] where exceptionally high purity is required, double distilled water is used. Any dissolved solids such as salt, bacteria, calcium or iron remain solid while the pure water converts to a much lighter steam and is drawn out for condensation, leaving most if not all solid contaminants behind. Distilled water is preferred for dilution as it’s a ‘known’ quantity (TDS 0) unlike domestic potable water. In larger chemical and biological laboratories, as well as industry, cheaper alternatives such as deionised water are preferred over distilled water.

c)        Purified water - is water that is mechanically filtered or processed to be cleaned for consumption. Distilled water and deionized (DI) water have been the most common forms of purified water, but water can also be purified by other processes including reverse osmosis, carbon filtration, microfiltration, ultrafiltration, ultraviolet oxidation, or electro dialysis. In recent decades, a combination of the above processes have come into use to produce water of such high purity that its trace contaminants are measured in parts per billion (PPB) or parts per trillion (PPT). Purified water has many uses, largely in science and engineering laboratories and industries, and is produced in a range of purities

What is the difference between a base and an alkali?

An Alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Alkalis are best known for being bases that dissolve in water. (Most common form is hydroxide.) A base is most commonly thought of as an aqueous substance that can accept H+ ions. A soluble base is also often referred to as an alkali if hydroxide ions (OH−) are involved.

Potential hydrogen  [: in chemistry, pH is a measure of the activity of the (solvated) hydrogen ion. p[H], which measures the hydrogen ion concentration is closely related to, and is often written as, pH .

Pure water has a pH very close to 7 at 25°C. Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline] [1]

Simply put the potential of hydrogen (pH) scale is a set of numbers between 0 and 14 where 0 (Hydrochloric acid) is the most acidic and 14 (Bleach or Lye) is the most alkaline (caustic) pH is a characteristic of water solutions only; without water, you cannot have a pH. The pH scale is logarithmic; for every integer that the scale decreases the material is 10 times more acidic.

Those of us in earthquake country know all too well the consequences of a change of from 6 to 7 on the logarithmic, Richter scale. The difference in the pH scale is just as dramatic and therefore just as misleading.

I hope the above article was informative. By having some understanding of the ‘What’ and ‘Why’ as well as the ‘How’ along with a little science to help you understand how the chemicals we use react, you can achieve the results you desire.

 I would appreciate it if you would share this article as it helps other detailers further their knowledge. Questions and/ or constructive comments are always appreciated.

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