chem unit 4 test review

Question 1

what’s a solution

Answer 1

homogeneous mixture of two or more substances where the solute is uniformly distributed within the solvent.

Question 2

characteristics of a solution

Answer 2

-Homogeneous: Uniform composition throughout.
-Stable: Solute particles do not settle over time.
-Can exist in various phases: solid, liquid, or gas

Question 3

define concentration

Answer 3

The amount of solute present in a given quantity of solvent or solution.

Question 4

dissociation

Answer 4

The process where ionic compounds separate into individual ions in water.

Example: NaCl → Na (aq) + Cl (aq)

Question 5

hydration

Answer 5

-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.

Question 6

miscibility

Answer 6

Refers to the ability of two liquids to mix and form a homogeneous solution.

Question 7

factors affecting miscibility

Answer 7

-Polarity: “Like dissolves like” - solutes dissolve in solvents of similar polarity
-Intermolecular Forces: Hydrogen bonding, dipole-dipole interactions, and London dispersion forces.

Question 8

surfactants

Answer 8

Surfactants are compounds that reduce surface tension between two substances, such as oil and water, allowing them to mix

Question 9

structure of surfactants

Answer 9

-Hydrophilic Head: Water-loving (polar) part that interacts with water.
-Hydrophobic Tail: Water-fearing (nonpolar) part that interacts with oils and grease.

Question 10

how surfactants work

Answer 10

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.

Question 11

degrees of saturation

Answer 11

1. unsaturated: holds less solute at given temp
2. saturated: holds max amount of solute at given temp
3. supersaturated: more solute than saturation point (achieved by heating or cooling)

Question 12

solubility curves key features

Answer 12

-Solubility increases with temperature for most solids.
-Gases behave inversely, with solubility decreasing as temperature rise

Question 13

solubility of ionic compounds __ with temperature

Answer 13

increases

Question 14

solubility of gases __ as temperature increases

Answer 14

decreases.

When the pressure of a gas above a liquid increases, more gas molecules are “forced” into the liquid, increasing solubility.

Question 15

stock solution

Answer 15

A highly concentrated solution used as a starting point to prepare more dilute solutions for practical applications

Question 16

standard solution

Answer 16

A solution prepared in the laboratory with a precisely known concentration, often used for experiments and calibrations.

Question 17

dilution C1V1 = C2V2

Answer 17

Dilution is the process of decreasing the concentration of a solution by adding more solvent without adding more solute

Question 18

concentrations and consumer products

Answer 18

solute/solution x 100%

for ppm x10^6
ppb x 10^9
ppt x 10^12

Question 19

total ionic equation shows ..

Answer 19

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)

Question 20

net ionic equations show …

Answer 20

only the species that actually change during the reaction.

Question 21

properties of acids and bases

Answer 21

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

Question 22

arrhenius theotry of acids and bases

Answer 22

-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

Question 23

titration (stichometry)

Answer 23

procedure used to detrimine the concentration of one solution using another standarized solution (titrant)

Question 24

equivalence point and endpoint

Answer 24

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