General Chemistry Ch. 13 - The Properties of Mixtures: Solutions and Colloids
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| show | The substance that dissolves into the solvent
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| show | The solution into which the solute dissolves
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| Solubility (S) | show 🗑
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| Is the solvent always the most abundant component of a given solution? | show 🗑
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| Miscible | show 🗑
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| Dilute/concentrated | show 🗑
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| Side note: butter doesn’t dissolve in water but it dissolves in… | show 🗑
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| How do intermolecular forces relate to solubility? | show 🗑
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| Dissolve: ionic compounds in water | show 🗑
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| The size of the hydration shell (i.e. the number of water molecules surrounding the ion) depends on | show 🗑
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| Dissolve: Hydrogen bonds in water | show 🗑
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| show | In the absence of H-bonds dipole-dipole forces account for the solubility of polar organic molecules such as acetaldehyde (CH3CHO) in non polar aqueous solutions like chloroform (CHCl3)
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| show | Example: Fe^2+ (iron ion) in hemoglobin binding to O2 in the bloodstream.
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| show | Because an ion increases the magnitude of any nearby dipole, ion-induced dipole forces also contribute to the solubility of salts in less polar solvents.
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| Dissolved dipole-induced dipole forces | show 🗑
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| show | Contribute to the solubility of all solutes in all solvents.
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| show | In water: they’re not like substances, H-bonds can’t be substituted by the dispersion forces of the oil and vice versa. In hexane: they both have a lot of dispersion forces which can be substituted for one-another.
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| show | Alcohol CH3(CH2)nOH = hydrocarbon with a hydroxyl group. The hydrocarbon portion is hydrophilic and not very soluble in water; the hydroxyl group however has H-bonds and is very soluble. n is proportional to its size
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| Alcohol’s solubility in water and hexane as related to the size of the molecule | show 🗑
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| Why is N2 not very soluble in water | show 🗑
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| show | Because it binds to the iron in hemoglobin
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| Some nonpolar substances appear to dissolve more readily in solvents due to… | show 🗑
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| show | All gases are infinitely soluble in one another. E.g. air which is a solution containing about 18 different gases.
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| Gas-solid solutions | show 🗑
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| show | By passing an impure sample through a solid metal such as palladium. Only the H2 molecules are small enough to enter the spaces between the Pd atoms.
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| show | Because solids diffuse so little, their mixtures are usually heterogeneous; an example is gravel mixed with sand. Some solid-solid solutions can be formed by melting the solids and then mixing them, e.g. alloys.
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| show | e.g. brass and sterling silver, atoms of another element substitute for some of the main element’s atoms.
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| Interstitial alloys | show 🗑
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| show | Unbranched polymers formed from monomers called amino acids. They range from 50 amino acids to several thousand. Protein shapes are determined completely by the sequence of amino acids in the chain.
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| Amino acids | show 🗑
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| Side chain | show 🗑
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| Peptide bond | show 🗑
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| show | An alpha-carbon bonded to a peptide bond which is bonded to the next alpha-carbon and so forth with various side chains dangling off them.
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| show | The -SH ends of two cysteine side chains often form an -S-S- bond, a covalent “disulfide bridge” that brings together distant parts of the chain.
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| show | Sometimes oppositely charged side chains lie near each other and the –COO- and –NH3+ groups form an electrostatic salt link (or ion pair), which secures the chain’s bends.
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| The amino acid sequence determines a protein’s shape, and the shape determines the… | show 🗑
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| Soap | show 🗑
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| How does soap help clean grease on your hands? | show 🗑
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| Detergent vs. soap | show 🗑
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| show | Molecules consisting of two long fatty acid chains and a charged organophosphate group linked to glycerol, a three-carbon trialcohol. In head, the head is polar, the tail is not.
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| show | Self assemble into lipid bilayers, a sheetlike double layer of molecules where the polar heads cover the surfaces and the nonpolar tails face each other on the interior.
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| How do proteins orient themselves on lipid bilayers? | show 🗑
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| Action of antibiotics | show 🗑
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| Nucleic acids | show 🗑
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| Mononucleotides | show 🗑
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| The repeating patter of a DNA chain | show 🗑
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| Structure of double helix | show 🗑
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| show | Polymers containing monomers called monosaccharides (or simple sugars).
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| show | Cellulose, starch, and glycogen all consist entirely of glucose monomers but differ in the way they’re linked and extent of crosslinking.
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| Cellulose | show 🗑
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| show | The countless H-bonds among cellulose chains which promote H-bonding and dispersion forces.
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| For one substance to dissolve another, three events must occur: | show 🗑
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| No matter what the nature of the attractions within the solute and within the solvent… | show 🗑
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| show | Solute particles separate from each other. This step involves overcoming intermolecular attractions, so it is ENDOTHERMIC: Solute (aggregated) + heat -> solute (separated). deltaH_solute > 0
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| show | Solvent particles separate from each other. This step also involves overcoming attractions, so it is ENDOTHERMIC: Solvent (aggregated) + heat -> solvent (separated) deltaH_solvent > 0
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| Solvent particles, step 3 | show 🗑
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| show | The total enthalpy change that occurs when a solution forms from solute and solvent
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| show | (Yet another application of Hess’ law): deltaH_soln = deltaH_solute + deltaH_solvent + deltaH_mix
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| show | (deltaH_solute + deltaH_solvent) < |deltaH_mix|. Thus, deltaH_soln would be negative
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| show | The solute may not dissolve to any significant extent in that solvent.
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| The deltaH_solvent and deltaH_mix components of heat of solution are difficult to measure individually. Combined these terms represent the enthalpy change during… | show 🗑
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| show | The process of surrounding a solute particle with solvent particles.
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| Hydration | show 🗑
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| show | The enthalpy change for separating the water molecules (deltaH_solvent) and mixing the solute with them (deltaH_mix) are combined into heat of hydration (deltaH_hydr)
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| Using heat of hydration what does the thermochemical solution cycle formula become? | show 🗑
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| show | Charge density
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| show | The ion’s charge to its volume
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| Heat of hydration trend | show 🗑
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| show | 2+
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| show | Small
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| show | Down a group: charge density decreases, across a period: charge density increases
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| The energy required to separate an ionic solute into gaseous ions is its … | show 🗑
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| show | If the lattice energy is about the same as the heats of hydration, there will be no noticeable temperature change. If the lattice energy is much smaller, then very exothermic and hot. If the lattice energy is much larger, then endothermic/hot.
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| Entropy (S) | show 🗑
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| Compare entropy of liquid vs. solid | show 🗑
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| Compare entropy of gas and liquid | show 🗑
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| A solution usually has higher entropy than… | show 🗑
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| show | The change in enthalpy and the change in entropy
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| Systems tend toward … | show 🗑
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| At what point is a solution saturated? | show 🗑
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| show | It will not dissolve.
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| Unsaturated | show 🗑
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| Supersaturated | show 🗑
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| show | By dissolving solute in the material while it’s warmed up because it has higher solubility at higher temperature. Then cool the material down and it will be supersaturated because it has exceeded its solubility at the cool temperature.
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| Are all solids more soluble at higher temperatures? | show 🗑
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| show | Decreases. Why? Gases have weak molecular forces so there are relatively weak interactions between gas and water. Thus, when temperature increases, gas is able to easily break free and return to gas phase.
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| show | Solute(g) + water(l) -> saturated solution(aq) + heat
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| Thermal pollution | show 🗑
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| show | Very little because liquids and solids are virtually incompressible.
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| show | Henry’s law expresses the quantitative relationship between gas pressure and solubility: the solubility of a gas (S_gas) is directly proportional to the partial pressure of the gas (P_gas) above the solution: S_gas = k_H * P_gas
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| show | Henry’s law constant.
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| Molarity | show 🗑
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| Why would expressing concentration in terms of molarity have drawbacks (1)? | show 🗑
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| Why would expressing concentration in terms of molarity have drawbacks (2)? | show 🗑
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| Molality | show 🗑
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| Note regarding the difference between the denominators of molarity and molality | show 🗑
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| Why does molality use mass rather than volume? | show 🗑
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| Special relationship between molarity and molality for water | show 🗑
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| Parts by mass | show 🗑
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| show | [ Mass of solute / (mass of solution) ] * 100
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| Sometimes mass percent is symbolized … | show 🗑
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| show | Volume of solute / volume of solution
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| show | [Volume of solute / volume of solution] * 100
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| show | % (v/v)
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| % (w/v) | show 🗑
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| Mole fraction (X) | show 🗑
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| show | Mole fraction * 100
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| Colligative properties | show 🗑
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| show | Vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure
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| Nonvolatile electrolytes | show 🗑
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| Vapor pressure lowering (deltaP) | show 🗑
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| Raoult’s law | show 🗑
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| An ideal solution | show 🗑
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| In practice, Raoult’s law gives… | show 🗑
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| show | A solution boils at a higher temperature than the pure solvent.
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| Why does boiling point elevation occur? Boiling point = the temp at which its vapor pressure equals the external pressure. And…. | show 🗑
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| Equation for boiling point lowering | show 🗑
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| show | The boiling point elevation; a positive value: deltaT_b = T_b(solution) – T_b(solvent)
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| Freezing point | show 🗑
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| show | deltaT_f. the magnitude is proportional to the molal concentration of solute: deltaT_f = K_f*m. Where K_f is the molal freezing point depression constant.
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| show | Freezing point depression; a positive value: deltaT_f = T_f(solvent) – T_f(solution)
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| show | A membrane that allows solvent, but not solute
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| The phenomenon caused by a semipermeable membrane is called | show 🗑
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| Osmotic pressure | show 🗑
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| show | The number of solute particles in a given volume of solution, that is, to the molarity.
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| Equation for osmotic pressure | show 🗑
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| Review: what can solute not do? | show 🗑
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| show | The presence of the solute decreases the mole fraction of the solvent, which lowers the number of the solvent particles leaving the solution per unit time; this lowering requires an adjustment to reach equilibrium again.
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| Of the four colligative properties, _____ creates the largest changes and therefore the most precise measurements | show 🗑
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| show | P_total = (X_solvent * P°_solvent) + (X_solute * P°_solute). The presence of each volatile component lowers the vapor pressure of the other by making each mole fraction less than 1.
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| The vapor has a higher mole fraction of the… | show 🗑
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| show | The ratio of the measured value of the colligative property in the electrolyte solution to the expected value for a nonelectrolyte solution
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| show | i = (measured value for electrolyte solution) / (expected value for nonelectrolyte solution)
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| To calculate the colligative properties of strong electrolyte solutions, we… | show 🗑
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| If strong electrolyte solutions behaved ideally, the factor i would be… | show 🗑
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| Are strong electrolyte solutions ideal? | show 🗑
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| The measured value of the van’t Hoff factor is typically _____ than expected. Why? | show 🗑
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| Ionic atmosphere | show 🗑
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| Why is nonideal behavior of solutions more common than nonideal behavior of gases? | show 🗑
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| show | Heterogeneous mixture containing particles large enough to be seen by the naked eye and clearly distinct from the surrounding fluid.
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| show | Solution: A homogenous mixture in which the particles are individual molecules distributed evenly throughout the surrounding fluid.
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| show | The middle ground between suspensions and solutions, in which a dispersed (solute-like) substance is distributed throughout a dispersing (solvent-like) substance. E.g. proteins, synthetic polymers, etc.
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| The size of colloidal particles | show 🗑
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| show | They have an enormous surface area which allows many more interactions to exert a great total adhesive force, which attracts other particles and leads to practical uses of colloids.
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| Foam | show 🗑
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| show | The light scattering phenomenon observed when light passes through colloids: the light is visibly broader than one passing through a solution, e.g. sunlight passing through dust.
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| show | A characteristic movement in which the particles change speed and direction erratically. This motion results because the colloidal particles are being pushed this way and that by molecules of the dispersing medium.
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| Why is Brownian motion significant | show 🗑
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| When colloidal particles collide why don’t they aggregate into larger particles? | show 🗑
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| Strategies to eliminate colloids | show 🗑
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