To determine the moles of water attached to one mole of anhydrate of a hydrate.
Chemistry can be defined as the science of matter, and its interaction with other matter.
The periodic table acts as the foundation of chemistry, which is a chart that lists elements by
atomic number and by electron arrangements, so that elements with similar chemical properties
are in the same column. The elements, substances which cannot be separated into simpler
substances, can join in a variety of ways. Ways in which elements can join together are through
ionic bonding, covalent bonding, and metallic bonding. Elements which join together form
A hydrate can be defined as a compound with water molecules attached to it and as part
of its composition. In a hydrate, the water molecules are usually loosely held to the compound
itself. A hydrate is usually expressed in the simplest formula, its empirical formula, which is a
formula in which all coefficients are reduced to the smallest whole number ratio. The compound
in a hydrate is referred to as the salt.
Water molecules attached to a hydrate still retain the properties of water, thus, having a
boiling point of 100°C . When a hydrate is heated, all the water evaporated until the compound
gets to a certain constant mass, where there are no longer any water molecules remaining. At this
point, the compound alone is the anhydrate, also referred to as the anhydrous salt and anhydrous
compound, with no water molecules attached to it.
When water molecules undergo evaporation,
water molecules expand and slowly take the form of a gas. Little by little, water enters the air
was water vapor and are no longer attached to the salt. When the salt of the hydrate is left alone,
however, moisture (water vapor) in the air attaches to the anhydrate once again to form a
hydrate. Therefore, one must continue to evaporate the water molecules off the hydrate until it
reaches a constant mass or until it can be affirmed that all water molecules have been evaporated.
In a hydrate, the number of water molecules always differs. Some compounds may have
1 mole of water attached, some as many as 10, some may even have fractional moles of water
molecules. Hydrates are named after the number of water molecules attached, thus a compound
with two molecules attached would be called a dihydrate.
All hydrates take the form of
compound · xH
O, where x is the number of moles of water attached to its anhydrous compound.
In solving for a variable, x, first, the mass of the total water evaporated must be