17 Questions
What technique can be used to obtain larger particles of a precipitate by controlling the pH?
Mixed-Crystal Formation
Which method is effective in coagulating a colloidal suspension by increasing electrolyte concentration?
Occlusion
What process involves a short period of heating and stirring to coagulate a colloidal suspension?
Surface Adsorption
Which technique involves carrying normally soluble compounds out of a solution with a precipitate?
Peptization
How can the particle size of crystalline solids be significantly improved?
By minimizing Q, maximizing S, or both
What is the benefit of having precipitates made up of large particles in gravimetric work?
Large particles are easily filtered and washed free of impurities
What is a characteristic of colloidal particles?
They show no tendency to settle from solution
What is the size range of particles that make up a colloid?
Less than 10^-4 cm
What does a small (Q - S)/S value indicate about a precipitate?
It tends to be colloidal
What is nucleation in the context of precipitate formation?
A process where stable solid forms from atoms, ions, or molecules joining together
What influences the rate of nucleation during precipitate formation?
Relative supersaturation
What is the purpose of digestion in reducing coprecipitation?
To help reduce occlusion and mechanical entrapment
What is homogenous precipitation?
Formation of a precipitate by slow generation of a reagent throughout a solution
What happens after filtration of a gravimetric precipitate?
The precipitate is washed and then ignited
Why are homogeneously formed precipitates better suited for analysis?
Because they are easier to weigh accurately
What occurs during the ignition step of precipitates?
The precipitate is heated to decompose the solid and form a compound of known composition
How are results of a gravimetric analysis computed?
From the mass of sample and the mass of a product with known composition
Learn methods to control the particle size of crystalline precipitates such as elevating temperature, adjusting pH, and optimizing solubility and stirring techniques. Understand how to achieve desired particle sizes for crystalline solids.
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