Chapter 14: Mixtures and Solutions Flashcards
Colloids (Settles?, Scatters Light?, Relative Particle Size, Ex)
No; Yes; Medium; Corn starch + H2O
Solutions (Settles?, Scatters Light?, Relative Particle Size, Ex)
No; No; Smallest; Sugar + H2O
Suspensions (Settles?, Scatters Light?, Relative Particle Size, Ex)
Yes; Yes; Largest; Sand + H2O
Heterogeneous
Non-uniform
Homogeneous
Uniform
Alloys
Solid solutions of metals
Colloids
Suspensions of particles large enough to stay suspended, but not small enough to settle, suspended by Brownian Motion
Tyndall Effect
Scattering of light by a colloid
Solutions
Homogeneous mixtures of two or more pure substances
Solvent
Most abundant material
Solutes
Everything else
Brownian Motion
The process of keeping particles aloft in a fluid mixture, caused by collisions with other molecules
Soluble
A gas or solid that can dissolve in a given solvent
Insoluble
A gas or solid that will not dissolve in a given solvent
Miscible
2 liquids that form a solution
Immiscible
2 liquids that can’t form a solution
“Like Dissolves Like”
Polar solvents dissolve polar and ionic solutes; Non-polar solvents dissolve non-polar solutes
Concentration
Amount of solute in a given amount of solvent
Thixotropic Mixtures
Solid-like mixture that may become fluid when stirred or agitated
Qualitative Ways To Express Concentration
- Strong
- Weak
- Concentrated
- Dilute
Quantitative Ways To Express Concentration
- % by mass
- % by volume
- Molarity (M)
- Molality (m)
- Mole fraction
- Dilution Equation
Molarity (M)
moles solute/L solution = moles dm^-3
[ ]
Molar concentration
Equation Relating Molarity & Volume
M1V1=M2V2
Unsaturated
A solution in which more solute may be dissolved (Dissolution>crystallization)
Saturated
A solution in which no more solute may dissolve (Dissolution=crystallization)
Supersaturated
An unstable solution that holds more solute than normally possible (Dissolution<crystallization when disturbed)
Colligative Properties
Physical properties of solvents that change with [solute particles]; Increase [solute particles] = increase [solute] = increase (moles particles/mole solute) = increase boiling point, decrease freezing point, decrease vapor pressure, & increase osmotic pressure
Osmosis
Diffusion over a semi-permeable membrane - water moves to equalize concentrations
Freezing Point Depression
Solute particles interfere with crystal formation
Vapor Pressure Depression
- Solute particles @ surface of liquid block sites for escape of solvent vapor
- Solute particles “hold on” to solvent molecules, making it harder for molecules to escape as a vapor
Boiling Point Elevation
Because boiling point occurs when vapor pressure > or = atmospheric pressure, if vapor pressure is decreased by solute, a higher boiling point is needed to increase vapor pressure
Solvation
Process of dissolving one substance in another
Factors Affecting Rate Of Solvation
- Stirring
- Surface Area
- Temperature
- Pressure (Gases Only)
- Nature Of Solute & Solvent
Formation Of Solutions
Intermolecular forces between solute and solvent particles must be strong enough to compete with those between solute particles and those between solvent particles - As solution forms, solvent pulls solute particles apart and surrounds or solivates them
Gas Solubility
- Increase pressure = increase solubility
- Decrease temp = increase solubility
- Increase molecular mass = increase solubility (due to LDF)
Solubility Curves
Visual representation of temp vs solubility
