Honors Chemistry Semester 2 Final Exam
How do you name acids?
Binary acid: hydro + first syllable of the nonmetal + ic + acid Ternary acid: 1. Start with the first one or two syllables of the name of the nonmetal 2. Add -ic if the polyatomic ion ends in -ate. Add -ous if the polyatomic ion ends in -ite 3. Add acid
What do both diffusion and effusion depend on?
Both diffusion and effusion depend on the molar mass of the gas. Gas molecules will diffuse and effuse faster if they have a lower molar mass.
Combustion reaction
~One of the reactants is always O2 gas because in order for something to burn, oxygen needs to be present ~One of the reactants is also a hydrocarbon compound (a compound including hydrogen and carbon) ~The products will be carbon dioxide and water
What does the direction of the arrow tell us about and acid/base chemical equation?
~Single arrow: the strong acid and strong base dissociate completely into a weak acid and weak base ~Double arrow: the weak base and weak acid slightly dissociate into a stronger acid and a stronger base
Describe how freezing point is lowered
~Solids form crystals when molecules make an orderly pattern called "crystals" (freezing) ~The solute that is added breaks up the orderly pattern ~How much the freezing point is lowered depends on the amount of solute dissolved
Strong acids vs weak acids
~Strong acids are strong electrolytes because they donate hydrogen ions so easily that their dissociation in water is nearly complete; they conduct electricity well ~Weak acids are weak electrolytes because they dissociate slightly in water; they are poor conductors of electricity
Strong bases vs weak bases
~Strong bases are strong electrolytes that dissociate completely in water; they are good conductors of electricity ~Weak bases are weak electrolytes that are poor acceptors of hydrogen ions and produce very few ions in solution; they are poor conductors of electricity
What is the difference between a strong and a weak electrolyte?
~Strong: completely dissociate into its ions (ionic compounds); very good conductors of electricity ~Weak: will not completely dissociate (mostly molecules, some ionic compounds); poor conductors of electricity
Describe how boiling point is elevated
~The vapor pressure determines the boiling point ~Lower vapor pressure means you need a higher temperature to get it equal to the atmospheric pressure ~The number of dissolved particles determines how the boiling point is elevated as well as the solvent
What are the three stages of saturation?
~Unsaturated: less than the maximum amount of solute has been added (more solute can still be dissolved) ~Saturation: the solution has the maximum amount of solute that can dissolve at that temperature and pressure ~Supersaturated: more solute has been added that can dissolved (past the maximum defined by saturation)
How does pressure affect equilibrium in Lechatlier's principle?
~Volume and pressure are in an inverse relationship ~Pressure increases/volume decreases: shift in the direction with less moles of gas ~Pressure decrease/volume increase: shift in the direction with more moles of gas ~Only used for reactions that contain gases because we can predict the shift in equilibrium based on the number of moles of gas on the reactant and product sides
Theoretical yield
The amount of product that can be made by a reaction
Lechatlier's principle
If a stress is put on a reaction that is at equilibrium, it will proceed in a way to return to equilibrium
Name and describe the three chemical reactions used with acids and bases.
1. Acid reacting with a metal ~Metal + acid ---> H2 + salt ~Single replacement reaction 2. Acid reacting with a carbonate/bicarbonate ~Acid + carbonate---> CO2 + H2O + salt ~Double replacement reaction 3. Neutralization reaction ~Base + acid ---> H2O + salt ~Double replacement reaction
What is the equilibrium constant for the autoionization of water?
1.0 x 10^-14
How would one calculate the concentration of H3O+ or OH- ions in a solution when given one or the other?
1.0 x 10^-14= [H3O+][OH-]
What is the difference between the Arrhenius, Bronsted-Lowry, and Lewis theories of acids and bases?
1. Arrhenious acids and bases ~Acids: dissociate into water to increase the concentration of H+ ions ~Bases: dissociates into water to increase the concentration of OH- ions 2. Bronsted-Lowry acids and bases ~Acids: can donate a hydrogen ion to another substance ~Bases: can accept a hydrogen ion 3. Lewis acids and bases ~Acids: accept electrons ~Bases: donate electrons
List the five types of chemical reactions
1. Combination reaction 2. Decomposition reaction 3. Single replacement reaction 4. Double replacement reaction 5. Combustion reaction
What are the three important colligative properties of solutions?
1. Vapor pressure lowering 2. Boiling point elevation 3. Freezing point lowering
How many representative particles are in a mole (Avogadro's number)?
6.022 x 10^23
Hydrate
A compound that is present with water molecules attached
Calorimeter
A device used to measure the transfer of heat
Colligative properties
A property of solution that depends on the number of solute particles in solution but not on the specific type of particle ~Molecular compounds do not dissociate into ions, so they will have one particle in solution ~Ionic compounds such as NaCl will dissociate into two ions, so it will have two particles in solution ~Ionic compounds such as CaCl2 will dissociate into three ions, so it will have three particles in solution
Reversible reaction
A reaction when the products can go back to their reactant form ~Is indicated with a double arrow
Buffer
A solution that maintains the pH of a solution by neutralizing the addition of small amounts of acid and base
Indicator
A substance added to a titration sample that changes color when the pH of the solution changes
Solute
A substance that is the smaller amount uniformly dispersed in another substance called the solvent; substance being dissolved in a solution
How does a catalyst affect equilibrium in Lechatlier's principle?
Addition of a catalyst will not change equilibrium
What are the three ways of finding concentration?
Amount of solute/amount of solution 1. Mass percent concentration (mass/mass) ~Keep units constant 2. Volume percent concentration (volume/volume) ~Keep units constant 3. Mass volume percent concentration (mass/volume) ~Volume in mL
What is the difference between an endothermic and exothermic reaction?
An endothermic reaction is a reaction in which heat is gained by the system and lost by the surroundings. An exothermic reaction is a reaction in which heat is lost by the system and gained by the surroundings.
Rate law
An expression for the rate of a reaction in terms of the concentration of reactants only ~Rate= k[A]^m[B]^n ~Only use [B] if there is more than one reactant
What are the three main units for pressure and the conversion factor between them?
Atmosphere (atm) Millimeters of Mercury (mmHg) Kilopascals (kPa) 1 atm= 760 mmHg= 101.3 kPa
Reaction rate of a chemical reaction and its formula
The change in concentration of a reactant or product per unit of time (DELTA)[A]/(DELTA)t ~[A]: concentration of a reactant or product (M) ~t: time (consistent units)
Dilution
Decreasing the concentration of a solution by adding solvent ~M1V1=M2V2 ~Inverse relationship between molarity and volume of a solution ~Volume in L
Effusion
Gas will escape through a tiny hole in a container ~Example: box with a divider; balloon slowly deflates, coffee lid
Describe a phase diagram
Gives the temperature at which a substance exist as a solid, liquid, or gas (vapor) ~X-axis: temperature (degrees C) ~Y-axis: pressure (atm) ~Normal melting and boiling point are horizontal to standard pressure (1 atm) ~Sublimation occurs from left to right; deposition occurs from right to left across the line between solid and gas ~Melting occurs from left to right; freezing occurs from right to left across the line between solid and liquid ~Vaporization occurs from left to right; condensation occurs from right to left across the line between liquid and gas ~Triple point: the point at which all three curves on a phase diagram meet; the condition where all three phases exist in equilibrium
What are the strong acids?
HCl HNO3 H2SO4 H2CO3 H3PO4 HCH3COOH
What is the difference between an ideal gas and a real gas?
Ideal gasses do not exist like real gasses do. However, since real gasses and ideal gasses behave similarly at most temperature and pressures, we can use PV=nRT. Conditions where real gasses are most different from ideal gasses are at low temperatures and high pressures.
Describe the phrase "like dissolves like"
In molecular compounds, polar solvents will dissolve in polar solutes, and nonpolar solvents will dissolve in nonpolar solutes.
What does it mean when the equilibrium constant (Kc) is large/small?
Large: [Products]>[Reactants] Small: [Reactants]>[Products]
What is the difference between molarity and molality?
Molarity (M): moles of solute/1 liter of solution Molality (m): moles of solute/kg of solvent
Does concentration of a solution affect the strength of that acid or base?
No
Conjugate acid/base pairs
Molecules or ions related by the loss of one H+ by and acid and the gain of one H+ by a base
Decomposition reaction
One reactant that will break into or decompose into at least two products ~Compound----> element or compound + element or compound
Dalton's Law of Partial Pressures
P(total)= P1 + P2 + P3
Combined Gas Law
P1 x V1/T1= P2 x V2/T2 ~Temperature needs to be in Kelvin
Boyle's Law
P1 x V1= P2 x V2 ~Inverse relationship between pressure and volume ~Pressure in kPa, atm, or mmHG (not Pa)
Gay-Lussac's Law
P1/T1=P2/T2 ~Direct relationship between pressure and temperature ~Temperature in Kelvin
Ideal Gas Law
PV=nRT ~P: pressure (depends on R) ~V: volume (L) ~n: amount of moles ~R: ideal gas constant ~T: temperature in Kelvin
Kinetic molecular theory
Particles are in constant random motion
Titration
Process by which we neutralize an acid sample with a known amount of base (neutralization chemical reaction)
What is not included in the "k" equilibrium constant? Why?
Pure liquids (water) and solids are not included because they have a constant concentration.
Excess reactant
Reactant that is leftover when the reaction stops
Limiting reactant
Reactant that limits how much product is made (reaction stops when this is used up)
In a solution, the solvent can be which states of matter?
Solid, liquid, gas
What are the equations needed to find the change in boiling point and freezing point temperature?
T(solution)= T(solvent) - change in freezing point T(solution)= T(solvent) + change in boiling point
Name each factor that affects rate of reaction and describe how it affects rate of reaction
Temperature: ~Direct relationship because at high temperatures, particles are moving with greater kinetic energy and more collisions occur Concentration of Reactants: ~Direct relationship because there are more particles with more collisions Catalysts: ~Speed up the rate of reaction and lowers the activation energy Particle size: ~Inverse relationship ~Smaller particle size will mean that there are more particles with more surface area, so there will be more collisions among the particles
Surface tension
The energy, or work, required to increase the surface area of a liquid due to intermolecular forces
Charles' Law
V1/T1=V2/T2 ~Direct relationship between volume and temperature ~Temperature in Kelvin
Activation energy
The minimum energy that colliding particles must have in order to react (energy barrier when going from reactants to products)
How do you name bases?
The name of the cation + hydroxide
Equivalence point
The point at which the moles of acid is equal to the moles of base (happens at around a pH of 7)
Chemical equilibrium
The point at which the rate of the forward reaction is equal to the rate of the reverse reaction and the concentrations of the reactants and products do not change (dynamic equilibrium: the rate are equal but they do not stop, the reactions are still occurring)
Orders of a reaction
The power to which the concentration of a reactant must be raised to match the experimental data on concentration and rate
Avogadro's Law
V1/n1=V2/n2 ~Volume is directly proportional to number of moles
Solvation
The process by which an ionic compound dissociates into its ions in a polar solvent (usually water)
Hydration
The process of surrounding dissolved ions by water molecules (the oxygen end of the water is attracted to the positive ion, and the hydrogen end of the water is attracted to the negative ion)
Calorimetry
The science of measuring the amount of heat
How do you calculate boiling point elevation?
The size of the change in boiling point is determined by the molality ~(DELTA)T(b)=K(b) x m x n ~(DELTA)T(b) is the change in the boiling point temperature in degrees Celsius ~K(b) is a constant determined by the solvent (given) ~m is the molality ~n is the number of pieces it falls into when it dissolves
How do you calculate the freezing point depression?
The size of the change in freezing point is determined by molality: (DELTA)T(f)= K(f) x m x n ~(DELTA)T(f): the change in freezing point temperature in degrees Celsius ~K(f) is a constant determined by the solvent (given) ~m is the molality ~n is the number of pieces it falls into when dissolving
Solvent
The substance in which the solute dissolves; usually the component present in greater amount ~Usually is water
Diffusion
The tendency of molecules to move towards areas of lower concentration until the concentration is equal throughout ~Example: spraying perfume and it spreads throughout the room
Endpoint
The volume at which we see a color change after the indicator is added
How is calorimetry used?
To see how much energy different foods are releasing
Ionization of water
When two molecules of water react with each other, they form H3O+ and OH-. The products divided by the reactants would then simply be [H3O+][OH-] because water is a pure liquid that is not included.
What are the formulas for [H3O+] and [OH-]?
[H3O+]=10^-pH [OH-]+ 10^-pOH
What is the general equation for a chemical reaction?
aA + bB <--> cC + dD ~Lowercase letter is the coefficient ~Uppercase letter is the reactant or product
Graham's Law
~Law associated with the movement of gases ~States that the rate of effusion is inversely proportional to the square root of the molar mass ~Rate1/Rate2= (SQUARE ROOT OF)M2/M1
What is the formula including both pH and pOH?
pH + pOH = 14
Compare the pH and pOH scales.
pH: Higher pH is basic and lower pH is acidic (neutral=7) pOH: Higher pOH is acidic and lower pOH is basic (neutral= 7)
What are the formulas for pH and pOH?
pH= -log[H3O+] pOH= -log[OH-]
What is the equation used for energy calculations/calorimetry experiments?
q= m x c x (DELTA)T ~q= heat (Joules) ~m: mass (grams) ~C: specific heat (J/degrees c x m) ~(DELTA)T: change in temperature (degrees Celsius)
Collision theory
~A reaction is only going to take place when molecules collide with the (1) proper orientation and (2) sufficient kinetic energy ~Used to relate the properties of particles to the rates of reactions ~If particles do not have enough energy when they collide, then they bounce apart unchanged after their collision
How does concentration affect equilibrium in Lechatlier's principle?
~Add reactant: make products (shift to the right) ~Add product: make reactants (shift to the left) ~Remove reactant: make reactants (shift to the left) ~Remove product: make product (shift to the right)
Combination/synthesis reaction
~At least two reactants and only one product ~Element or compound + element or compound ----> compound
Base dissociation constant
~B (aq) + H2O (l) <--> BH+ (aq) + OH- (aq) ~Kb= [BH+][OH-]/[B] ~Products divided by reactants ~Weak base < 1 because it does not react or ionize 100% ~Strong base >(or equal to) 1 because it reacts or ionizes 100%
Percent yield
~Compares the theoretical yield to how much product was actual made in lab ~Actual yield/theoretical yield x 100
Double-replacement reaction
~Compound + compound ----> new compound + new compound ~Cations switch places ~Both reactants will begin in the aqueous state ~One product will be aqueous and the other will either be a solid precipitate (most of the time), liquid (normally water), or a gas ~Use solubility rules to determine which of the products is aqueous: if both are aqueous, then there is NO REACTION ~When these aqueous solutions are dissolved in water, they are separated into their ions- this is why these must be aqueous; mixing two solids would not create new compounds
What is the difference between an electrolye and a nonelectrolyte?
~Electrolyte: a substance that dissociates into ions when dissolved in water; conducts electricity ~Nonelectrolyte: a substance that does not dissociate into ions (molecular compound); does not conduct electricity
Single-replacement reaction
~Element + compound ----> new compound + new element ~Element moves into compound to form a new compound, and the element that was bumped out of the compound is the new element ~Metals can only replace metals; nonmetals can only replace nonmetals ~Use the activity series of metals to determine whether or not an element can replace another element in a compound; if not, there is NO REACTION ~Will have one aqueous and one other reactants; will have one aqueous and one other product; if there are two aqueous products, there is NO REACTION
How does temperature affect equilibrium in Lechatlier's principle?
~Endothermic: (DELTA)H is positive or heat is a reactant ~Exothermic reaction (DELTA)H is negative or heat is a product ~Increase in temperature: shifts in the endothermic reaction ~Decrease in temperature: shifts in the exothermic reaction
Stoichiometry
~Greek for "measuring elements" ~Calculations of the quantities in a chemical reaction, based on a balanced equation
Acid dissociation constant
~HA (aq) + H2O (l) <--> A- (aq) + H3O+ (aq_ ~Ka= [H3O+][A-]/[HA] ~Products divided by reactants ~Weak acid < 1 because it does not react or ionize 100% ~Strong acid >(or equal to) 1 because it reacts or ionized 100%
Describe how vapor pressure is lowered
~If more things are dissolving, vapor pressure decreases (inverse relationship) ~Surface area is reduced, so less evaporation occurs ~The bonds between molecules keep molecules from escaping, so in a solution, some of the solvent is busy keeping the solute dissolved ~This lowers the vapor pressure ~Electrolytes form ions when they are dissolved, making more pieces (more pieces= a bigger effect on vapor pressure)
What is the general equilibrium constant for a chemical reaction (Kc)?
~Kc= [Product]/[Reactants] ~Raise the concentration of each reactant/product to the power of its coefficient ~Kc= [C]^c[D]^d/[A]^a[B]^b
Describe the phase change diagram
~X-axis is increasing heat energy; y-axis is increasing temperature ~First incline: solid state (energy equation) ~First plateau: left to right is melting; right to left is freezing; use stoichiometry for (DELTA)H(fusion) ~Second incline: liquid state (use energy equation) ~Second plateau: left to right is evaporation; right to left is condensation; use stoichiometry for (DELTA)H(vaporization) ~Third incline: gas/vapor state: use energy equation ~Bottom arrow: left to right is sublimation
Describe the endothermic and exothermic reaction graphs
~X-axis is the reaction pathway; y-axis is the increasing potential energy ~Endothermic: heat is absorbed and (DELTA)H is positive; reactants have less energy than products ~Exothermic: heat is released and (DELTA)H is negative; reactants have more energy then products ~Activation energy: hill that the reaction needs to overcome before getting started ~Catalyst: visibly decreases the activation energy
