30 Questions
What is the reason for the formation of crystals during homogeneous nucleation and growth?
The extent to which the ions are soluble decreases when the pH changes in the right direction
What is the result of evaporation on the solution?
A state of super saturation
What is the advantage of very careful crystallization?
It is the best method of preparing materials that are extremely pure
What is the phenomenon where compounds can crystallize with different crystal structures?
Polymorphism
What is the importance of polymorphism in industrial manufacturing?
It is a major issue in industrial manufacturing
What is the primary driving force for drying in convective or direct drying?
Reduced air relative humidity
What is the limitation of applying high temperatures in convective or direct drying?
Product quality considerations
What is affected by the rate of precipitation?
The purity of the crystal
What is the purpose of reducing pressure in supercritical drying?
To lower the boiling point
What is the advantage of freeze drying in preserving biological properties?
It retains vitamins and bioactive compounds
What is the characteristic of natural air drying?
It takes advantage of unheated forced air
What is the consequence of using too hot air in convective or direct drying?
Crust formation or case hardening
What is the primary reason why evaporation occurs faster in areas of less pressure?
There is less exertion on the surface, allowing molecules to escape
What is the effect of a larger surface area on the rate of evaporation?
It increases the rate of evaporation
What is the relationship between the density of a substance and its rate of evaporation?
Higher density results in slower evaporation
What is required for boiling to occur?
A combination of heat and reduced pressure
What happens when molecules collide during the evaporation process?
Energy is transferred and the molecules may gain enough to escape
Why don't the molecules in a glass of water typically turn into vapor quickly?
They lack the energy to escape
What factors need to be considered when devising a strategy for drying grains?
Air temperature, relative humidity and moisture content
What is the typical result of increasing the internal energy of a solid substance?
A rise in its temperature to its melting point
What is the term for a substance that has undergone a complete phase change from solid to liquid?
Molten
What is the relationship between the melting point and freezing point of a pure crystalline solid?
The melting point is often equal to the freezing point
What is the effect of increasing pressure on the melting point of a substance?
It lowers the melting point
What is the relationship between the strength of intermolecular forces in a crystal and its melting point?
Weaker forces result in a lower melting point
What is viscosity a measure of in a fluid?
Its resistance to deformation at a given rate
What did Isaac Newton postulate about the shear stress between layers in a fluid?
It is directly proportional to the velocity gradient
Why is close temperature control essential in viscosity measurements?
To ensure accurate measurements of lubricants
What happens to the viscosity of a liquid as its temperature increases?
It decreases
What happens to the viscosity of a gas as its temperature increases?
It increases
What happens to the cohesive forces between molecules in a liquid as it is heated?
They decrease
Learn about the different methods of crystal formation, including changing pH levels and evaporation, and how they lead to nucleation and growth of crystals.
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