Chapter 22: Mixtures: Solutions, Colloidal Dispersions, and Suspensions
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What does the dispersed phase refer to?
to the particles scattered throughout the medium
What does the continuous phase refer to?
the medium in which particles are distributed
How are food mixtures classified?
classified by the size of particles distributed throughout the mixture
What are the 3 food mixtures? What size are the particles?
– Solutions: smallest particles – Colloidal dispersions: particles larger than those in solutions – Suspensions: largest particles
What is a solution?
homogenous mixture of 2 or more substances
The dispersed phase is called what in a solution? The continuous phase?
• Dispersed: solute - Continuous: solvent
Name 2 characteristics of the particles in a solution?
• Particles are small - Have a high level of kinetic energy
Can solutions form gels?
No
Name the 3 types of solutions based on their states of matter and provide examples.
– solids in liquids (salt or sugar in water) – liquids in liquids (flavorings and vinegars) – gas in liquids (carbonated beverages)
What is solubility?
the amount of solute that will dissolve in a solvent
What does Le Chatelier’s principle state?
when the chemical equilibrium changes, the equilibrium shifts to counteract the change
What is solubility affected by?
temperature, particle size, concentration, pH, agitation, and vapor pressure
How does temperature affect solubility? Compare solids and gases.
• Solids: amount of solute that a solvent will hold increases with temp (ex: candy production) • Gases: amount of gaseous solute that a solvent holds DECREASES as temp increases (ex: soft drinks lose their carbonation faster at room temp)
How does particle size affect solubility?
The smaller the solute’s particles are, the greater is the exposed surface area and the faster the solute will dissolve
What is concentration?
he measure of parts of one substance (solute) to the known volume of another (solvent)
What is a unsaturated solution? Saturated?
Unsaturated: solution that can dissolve more solvent at a given temperature Saturated: holding all the solute that will dissolve in a solvent at any given temperature
What is the saturation point?
When all water molecules have bonded to a solute, the solution is at the saturation point
What allows a solution to hold more solute?
Heat breaks bonds in the solute, allowing the solution to hold more solute
If a solution is heated then cooled, what forms?
Supersaturated solution
Ions with what charge are more soluble?
Singly charged ions tend to be more soluble than ions with 2 or more charges
Are smaller ions more soluble than larger ions?
Yes
Calcium carbonate dissolves in neutral water, but more quickly when what is added?
When an acid is added
What does agitation influence (2)?
• Agitation or stirring speeds the dissolving rate until the saturation point is reached • Agitation also adds a small amount of energy that slightly raises the temperature
What is vapour pressure? What is it important for?
– the pressure at which gases escape from and dissolve into a liquid at the same rate – important in maintaining gases in solution