Semester 2 Final Review Part 2 Flashcards
What is cohesion?
Attraction of liquid particles for each other
What is adhesion?
Attraction of liquid particles to particles of solid surfaces
Below the surface of a liquid, the particles are pulled?
Equally in all directions by cohesive forces
Surface particles are pulled only sideways and downwards because?
So they have a net downward force
Does it take energy to oppose net force and increase surface area?
Yes
What is surface tension?
The tendency of liquids to decrease surface area to the smallest size possible
A solid to a gas is called?
Sublimation
A gas to a solid is called?
Deposition
Does temperature change when a substance changes state?
No
It takes energy to overcome what?
The forces holding particles together
What is a good measure of the strength of the forces that hold particles together?
Boiling point and melting point
Do ionic substances have much higher forces of attraction than covalent substances?
Yes
Why do ionic substances have higher forces of attraction?
They are closer together
Compounds with smaller ions or bigger ions have the highest melting points?
Smaller ions because there are smaller distances between them
What are intermolecular forces?
Forces of attraction between molecules of covalent compounds
Are intermolecular forces weaker than the forces between atoms in the molecule?
Yes
What is a dipole?
One end of the molecule has a partial positive charge while the other has a partial negative charge
How will molecules orientate themselves in dipoles?
So that the opposite charges attract principle operates effectively
Is it true that very polar molecules have high dipole-dipole forces?
Yes
The more polar the molecules are,
The higher the boiling point of the substance
What is a special case of dipole-dipole interactions?
Hydrogen bonding
What is hydrogen bonding?
A hydrogen atom is bonded to a highly electronegative atom of one molecule which is attracted to two unshared electrons of another molecule
Is it true that compounds with hydrogen bonding have higher boiling points than comparable compounds?
Yes
When can a strong hydrogen bond form?
When a hydrogen atom is covalently bonded to very electronegative atoms in the upper-right part of the periodic table
How does a london dispersion force work?
When the electrons move toward one side of an atom or molecule, that side momentarily is negative and the other is positive
What is a london dispersion force?
The dipole-dipole force resulting from the uneven distribution of electrons and the creation of temporary dipoles
Nonpolar molecules can only experience what type of intermolecular force?
LDF
Polar covalent molecules experience both?
Dipole-dipole and LDF
Dipole-dipole force are generally stronger than?
LDF
Larger compounds (molar mass) have stronger?
LDF because its proportional to number os electrons present and molar mass
What is the enthalpy of fusion? ΔHfus
The energy added during melting or removed during freezing
What is the enthalpy of vaporization? ΔHvap
The energy added during vaporization or removed during condensation
Which one is greater: energy of vaporization or energy of fusion
Energy of vap. because more energy is needed to go from liquid to gas because particles are farther apart
Is this true? Molar enthalpy increases as a substance’s temperature increases. Molar enthalpy is highest at the boiling point.
Yes
What equation can be used to find the molar enthalpy of vaporization and fusion?
q=nΔHvap
q=nΔHfus
As a solid melts, the entropy of its particles ____
Increases
An increase of entropy due to a solid melting is?
entropy of fusion (ΔSfus)
As a liquid vaporizes, the entropy of the particles _______.
increases
An increase of entropy due to a liquid vaporizing is?
entropy of vaporization (ΔSvap)
A substances entropy of vaporization is much ____ than its entropy of fusion
Larger
Are intermolecular forces significant in the gaseous state?
No
What is the formula for Tmp?
ΔHfus/ΔSfus
What is the formula for Tbp?
ΔHvap/ΔSvap
What is a phase?
A region that has the same composition and properties throughout
What is dynamic equilibrium?
Particles are constantly moving between two or more phases yet there is no net change in the amount of substance in either phase
When does dynamic equilibrium exist?
When no heat is added or removed
What is a phase diagram?
A graph that shows the relationship between the physical state of a substance and the temperature and pressure of the substance
What are the 3 lines in a phase diagram?
Liquid-gas equilibrium, liquid-solid equilibrium, and solid-gas equilibrium
What is the triple point?
Where the temperature and pressure at which the three states of a substance coexist at equilibrium
What is the supercritical fluid?
The substance above the critical point
What is the critical point?
At a temperature and pressure where the liquid and vapor pressure phases are identical
What is a solution?
Homogeneous mixture, particles are molecule-sized so that the mixture is uniform
What is suspension?
Heterogeneous mixture that has been well-mixed, but particles will settle out over time
What is solvent?
The main ingredient in a solution, water is the most common solvent
What is the solute?
The substance that is dissolved in the solvent
What are colloids?
Stable heterogeneous mixtures, particles repel each other because they have an electric charge, particles will not collect into larger particles
Mixtures can be separated using what?
Physical properties
What are the methods of separation?
Filtering, centrifuge, decant, evaporate, distillation, chromatography
What is chromatography?
Separates compounds of mixture based on how quickly molecules dissolved in a mobile phase solvent move along a solid phase
What is distillation?
Separates boiling points of compounds based on their boiling points
What is a distillate?
Materials with lower vapor pressures evaporate first and are removed from the solution
What is parts per million (ppm)?
The amount of solute in the solution used to express the amount of an impurity in another substance
How is ppm calculated?
g of solute/g of solvent x 1000000
What is concentration?
Ratio of solute to solvent in a solution
What is molarity?
Mol solute/L solution
What is molality?
Mol solute/kg solution
What is the formula for a dilution?
M1V1 = M2V2
What does gas solubility depend on?
Temperature and pressure
What is Henry’s Law?
The solubility of a gas increase as the partial pressure of the gas on the surface of the liquid increases
The higher the pressure, the
More gas dissolves
The lower the pressure, the
Less gas dissolves
As temperature increases, the solubility of a gas
Decreases
Why are gases less soluble in high temperatures?
The increased motion allows gas molecules to escape from the solution
If you open warm pop what happens?
Gas bubbles will escape
What is solubility?
The maximum amount of solute that can dissolve in a solvent at a given temperature
What formula is used for solubility?
grams solute/100 g solvent
What does saturated mean?
Holds enough/as much solute as it can
Solubilities of solids _____ as temperature increases
Increase
What is important to remember with solubility?
Like dissolves like
What is an emulsion?
Made of colloid-sized droplets suspended in liquid in which they would ordinarily be insoluble unless stabilized
What is an electrolyte?
A substance that dissolves in a liquid solvent and provides ions that conduct electricity
What do strong electrolytes do?
Completely dissociate into ions and conduct electricity well (ionic compounds)
What do weak electrolytes do?
Provide few ions in a solutions, conduct electricity weakly
What is a nonelectrolyte?
A liquid or solid substance that does not allow the flow of an electric current (covalent compounds)
What do colligative properties depend on?
The number of particles of solute in a solution
What formula is used for freezing point depression?
Δtf = Kfm
What formula is used for boiling point depression?
Δtb = Kbm
What is a completion reaction?
All of the reactant reacts to form product
What is a reverse reaction?
The products can reform reactants
What is chemical equilibrium?
The forward and reverse reactions reach a state of balance in which the concentrations of the reactants and products remain the same even though individual atoms may be changing
What is the rate?
Speed at which a process occurs
What is a complex ion?
Any metal atom or ion that is bonded to more than 1 atom or molecule
What is a ligand?
Molecules or anions that readily bond to metal ions
What are complex ions formed from?
Transition metals
What is the solubility product of the salt in water?
Maximum concentration of salt in an aqueous solution
When do reversible reactions reach equilibrium?
When the concentration of the reactants and the products is constant
If Keq >1
Products are favored at equilibrium
If Keq <1
Reactants are favored at equilibrium
Keq=1
Equilibrium
What is stress?
Something that causes a change in a system at equilibrium
What are the 3 kinds of stress?
Change in concentration, temperature, and pressure
What happens when stress is applied?
Eq is disrupted and rates are no longer equal
What is Le Chatelier’s Principle?
System adjusts to reduce change
How does equilibrium shift right?
Add a reactant, remove a product
How does equilibrium shift left?
Remove a reactant, add a product
Exothermic reactions usually lead to a shift in favor of
Reactants
Endothermic reactants usually lead to a shift in favor of
Products
Changes in pressure can affect ____ at equilibrium
Gases
A pressure increase favors
The reaction that produces fewer gas molecules
Acids have a ____ taste?
Sour
Acids are usually?
Liquids or gases
Bases taste?
Bitter
Bases are what?
Good cleaning agent, slippery, usually solids
What are the seven common strong acids?
HCl, HBr, HI, nitric acid, sulfuric acid, HClO4, and HIO4
What are the seven common weak acids?
Acetic acid, HCN, HF, HNO3, nitrous acid, sulfurous acid, HOCl, H3PO4
What are strong bases?
NaOH, KOH, Ca(OH)2, Ba(OH)2, Na3PO4
What are weak bases?
NH3, Na2CO3, K2CO3, C6H5NH2, (CH3)3N
