Experiment D: Hydrates Flashcards
What is the difference between ‘coordinated water’ and ‘lattice water’?
Coordinated water: bonded directly to the cation or anion
Lattice water: held in the crystal by hydrogen bonding but not associated with any particular ion
What’s is the water of hydration/ water of crystallization?
The water present is incorporated as an essential part of the crystal structure of the compound
What does efflorescent mean?
Hydrates that spontaneously lose water to the atmosphere
Why do efflorescent hydrates have the properties they do?
The loss of water occurs because the vapour pressure if water exerted by the efflorescent solid is greater that that of the vapour pressure if water in it’s surrounding atmosphere
What does hygroscopic mean? What else are they sometimes called?
Compounds that spontaneously absorb water from the atmosphere.
Widely used to dry liquids or gases they are sometimes called dessicants
Why do desiccant a have the properties they do?
The vapour pressure of the water extremes by the solid is less than that of the partial vapour pressure of water in the surrounding atmosphere
What does deliquescent mean?
Some compounds absorb water from the atmosphere so strongly they dissolve in their own water of hydration
How do you remove the water of crystallization from stable hydrates?
The hydrate must be heated to a temperature at which the vapour pressure of water exerted by the solid hydrate exceeds that of the partial pressure of water in the atmosphere
As a hydrate is heated the compound may undergo these changes:
A) it may undergo a colour change
B) the form of the crystal may chane- a dry powdery solid usually results
C) it may dissolve in it’s own water of crystallization, the water will then evaporate leaving the anhydrous solid
