chem unit 4 test review Flashcards
what’s a solution
homogeneous mixture of two or more substances where the solute is uniformly distributed within the solvent.
characteristics of a solution
-Homogeneous: Uniform composition throughout.
-Stable: Solute particles do not settle over time.
-Can exist in various phases: solid, liquid, or gas
define concentration
The amount of solute present in a given quantity of solvent or solution.
dissociation
The process where ionic compounds separate into individual ions in water.
Example: NaCl → Na (aq) + Cl (aq)
hydration
-Water molecules surround and stabilize the ions.
-The partial positive charge of hydrogen in water attracts anions.
-The partial negative charge of oxygen in water attracts cations.
miscibility
Refers to the ability of two liquids to mix and form a homogeneous solution.
factors affecting miscibility
-Polarity: “Like dissolves like” - solutes dissolve in solvents of similar polarity
-Intermolecular Forces: Hydrogen bonding, dipole-dipole interactions, and London dispersion forces.
surfactants
Surfactants are compounds that reduce surface tension between two substances, such as oil and water, allowing them to mix
structure of surfactants
-Hydrophilic Head: Water-loving (polar) part that interacts with water.
-Hydrophobic Tail: Water-fearing (nonpolar) part that interacts with oils and grease.
how surfactants work
1.Surfactants align at the interface of water and oil.
2.Hydrophobic tails embed in the oil, while hydrophilic heads interact with water.
3.Micelles form, trapping oil particles inside and dispersing them in water.
degrees of saturation
- unsaturated: holds less solute at given temp
- saturated: holds max amount of solute at given temp
- supersaturated: more solute than saturation point (achieved by heating or cooling)
solubility curves key features
-Solubility increases with temperature for most solids.
-Gases behave inversely, with solubility decreasing as temperature rise
solubility of ionic compounds __ with temperature
increases
solubility of gases __ as temperature increases
decreases.
When the pressure of a gas above a liquid increases, more gas molecules are “forced” into the liquid, increasing solubility.
stock solution
A highly concentrated solution used as a starting point to prepare more dilute solutions for practical applications
standard solution
A solution prepared in the laboratory with a precisely known concentration, often used for experiments and calibrations.
dilution C1V1 = C2V2
Dilution is the process of decreasing the concentration of a solution by adding more solvent without adding more solute
concentrations and consumer products
solute/solution x 100%
for ppm x10^6
ppb x 10^9
ppt x 10^12
total ionic equation shows ..
all the soluble ionic compounds dissociated into their respective ions in aqueous solution.
Example: For the same reaction:
Na⁺ (aq) + Cl⁻ (aq)+ Ag⁺ (aq) + NO₃⁻ (aq) → AgCl(s) + Na⁺ (aq) + NO₃⁻ (aq)
net ionic equations show …
only the species that actually change during the reaction.
properties of acids and bases
acids: ph less than 7, conductivity varies, sour, no special feel, colorless in phenolphthalein
bases: ph greater than 7, slippery feel, taste bitter, pink in phenolphthalein, blue
arrhenius theotry of acids and bases
-A base is an ionic compound that dissociates into cations and hydroxide ions when it dissolves in water. Hydroxide ions give bases their characteristic properties.
-An acid is a molecular compound that ionizes to produce hydrogen ions in water. Hydrogen ions give acids their characteristic properties
titration (stichometry)
procedure used to detrimine the concentration of one solution using another standarized solution (titrant)
equivalence point and endpoint
equivalence: point when neutralization is complete (the amount of acid and base added into the flask exactly match their mole ratio)
endpoint: when the indicator changes colour (this is how we know that the titration is complete and we can stop adding titrant
