(9) Hydrates and Hydrolysis

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What are hydrates?

Compound in which there is a chemical union between water and the molecules of certain substances- crystalline in appearance

The water held in the union of hydrates is called the…

water of crystallization

How can the waters of crystallization be removed?

Heating the compound (can be classified as a decomp reaction)

What gives some hydrates two distinctive forms?

Having two different waters of crystallization

When partly anhydrous, calcium sulfate is…

plaster of paris

when water is added to calcium sulfate, it becomes…

Gypsum

What is plaster of paris?

A hydrate traditionally employed in embalming to close the back of the skull after cranial autopsies. It hardens into gypsum and provides a seal for the cut edges of bone over which the scalp is sutured (recently replaced by calvaria clamps)

Plaster of paris is excellent for…

cases of extreme cranial trauma to reassemble broken bones

Where do we get the term “hardening compound” when describing solid autopsy compounds?

Plaster of paris. It can be used as one of these and acts as a dehydrating agent, effectively removing water from the viscera

What are hydrophillic substances?

those with an affinity for water that attract additional water. Can also be called hygroscopic

What is deliquescence?

process some hydrates can go through where they absorb enough moisture from the air under ordinary atmospheric conditions to dissolve (ex: calcium chloride)

Deliquescent substances are commonly used in caskets as…

mold inhibitors

What are efflorescent hydrates?

those that give up their water of crystallization to the surrounding air (ex: sodium carbonate)

Why must deliquescent and efflorescent substances be kept in tightly sealed containers?

to maintain their hydrated forms

What is hydrolysis?

process by which water is split by other compounds. constituents of water are then introduced into the products of the reaction. This is a principal chemical property of salts

How do you identify a hydrolysis reaction?

-Water appears on the reactant side of the equation
-Water is written as HOH, not h2o, to emphasize the reacting constituents (H+ and OH-)
-Products are an acid and base

In hydrolysis, the acid and base that are formed must be of…

different strengths

How is hydrolysis important in embalming?

It is the single most important factor in the initiation of decomposition. The proteins, carbs and fats are split into amino acids, monosaccharides, fatty acids and glycerin by the action of water and enzymes. Water chemically reacts with these substances.