deck_15162147 Flashcards
Arrhenius Model
Acids produce H+ ions, bases produce OH- ions
Bronsted-Lowry Model
Acids are proton (H+) donors and bases are proton accepters.
What are the 6 strong acids?
HCl, HI, HBr, HNO3, H2SO4, HClO4
Relationship b/w Ka and pH
Strong Acid = High Ka = Low pH (0-1)Weak acid = Low Ka = High pH (4-6)- pKa is the pH when chemical will accept or donate a proton- pKa = -log (Ka)
Relationship b/w Kb and pH
Strong Base = High Kb = High pH (10.1-14)Weak Base = Low Kb = Low pH (7.1-10)
Rule of thumb for pH and H+ concentration
Lower pH = Higher [H+]Higher pH = Lower [H+][H+] = [H3O-] b/c water is ignored Lol
Relationship between Ka and Kb
Kw = 1.0 * 10^-14 = Ka * KbpKa + pKb = 14pKa = -log (Ka)pKb = -log (Kb)
How do you know what the H+ concentration is of a strong acid or base
It is whatever the molarity is already given about the entire substance. But pay attention to the co-efficient.
What is the Keq formula
[products] / [reactants]
What is the Ka Equation?
[H+]*[Conjugate base]/ [Acid]
What does Kw mean?
Kw is the equilibrium constant of water (1.0 * 10^-14)pH of water = 7 pOH of water = 7
What is the Kb equation?
[Conjugate acid]*[OH-]/[Base]
What gets ignored in equilibrium constant calculations?
Solids and liquids
What does a lower pH mean in relation to H+ concentration?
Higher H+ Concentration (Acidic)
What does a higher pH mean in relation to H+ concentration?
Lower H+ Concentration (Basic)
What is the formula for Kp that shows the relationship between Kc (Keq) and Kp?
Kc * (RT)^∆nKc = [Products] / [Reactants]∆n = (Sum of coefficients of products) - (Sum of coefficients of reactants)R = 0.08206 (Latm) / (molKelvin) OR = 8.134 J/molT = Temperature in Kelvin
When do you use Q?
When you don’t know the equilibrium or the Keq.
What does amphoteric mean?
Can act as both an acid or base.
Do strong acids have an equalibrium?
No, because they completely ionize in water and it is very difficult for the acid to be formed again after disassociation.
Homogenous equilibria
Equilibrium in the same phase (g) -> (g)
Heterogenous equilibria
Equilibrium in different phases (aq) -> (g)
What are some important things to remember to do before starting any chemistry problem?
- check if the equation is balanced2. when doing stoichiometry and equilibrium problems, pay attention to the co-efficient.
Chemical Equilibrium
The ratio of concentrations of the reactants and products are constant over time. [Products] / [Reactants] Coefficients are the exponents. Highly dynamic microscopically, macroscopically static.
What happens if you add more reactant to a reaction mixture?
Keq goes right
What happens if you add more product to a reaction mixture?
Keq goes left
What does the catalyst do in a reaction mixture?
It increases the rate at which the rxn approaches the equilibrium but it does not change the position of the equilibrium. Catalysts also do not get consumed in the reaction.
What does Ka stand for?
Acid disassociation constant
What do strong acids and bases do in water?
Completely disassociates in water
Why do acids need water?
Acids do not show acidic behaviour in the absence of water because water being a polar solvent assists in the dissociation of acids into their respective ions.
What is a diprotic acid?
an acidthat yields two H+ ions per acid molecule
What is an oxyacid?
An acid with the acidic proton attached to an oxygen atom.
What is are monoprotic acids?
An acid thatonly donates one acid proton
What are organic acids?
Acids with a carbon atom backbone (usually carboxyl)
How to calculate pH from Molarity?
- Identify the major species of the acid/base. Also, consider if this is strong or weak. 2. set up an equilibrium reaction equation that makes sense for (1).3. Assume given molarity for the acid or base is the came concentration for the H+ solutionif it is a strong acid/ base. If it is a weak acid or base, assume the [H+] and the [Conjugate acid/base] are equal. 4. use the formulas to find [H+] for the weak acid or base. then use -log to get pH.
Are salts ionic compounds?
Yes. they also can act as an acid or base since they break up into ions in water. salt is just another name for ionic compounds.
Is NaOH a strong base?
Yes
Is NH3 an acid or base?
It is a weak base because it acts as a proton acceptor for NH4+.
How can you tell if something is an acid or base with zero information?
- If there are H+ or OH- ions in the compound2. Look at the polyatomic sheet, if an H+ is missing it is a base and if there is an extra H+ it is an acid?3. look at the formula and try to break apart the compund. the presence of H+ or OH- gives away if it was an acid or base. 3. Just pass…..away :)
What do the salts of strong acids and bases do
Give off neutral solutions (KCl and NaNO3)
What is a polyprotic acid?
An acid that can give up more than one proton sequentially. more than one reaction associated with it.
How is a neutral salt formed?
When a strong base and a strong acid react together.
How to calculate the [H30+]? aka [H+]
10 ^ -pH
How to calculate the [OH-]?
10 ^ -pOH
How to calculate % Ionization?
X/[Initial Acid/Base] * 100X = [H30+] or [OH-]
Examples of weak acids
H2SO3, HF, HClO, HNO2, H2CO3, HCN, HC2H3O3
Examples of neutral ions
Conjugate bases of strong acids: Cl-, Br-, I- NO3- SO4 2-, ClO4- Alkali Metals (Group 1?): Na+, Li+, K+
Examples of acidic ions
Ionic compounds with large positive charges: NH4+, Al+3, Pb +4, Fe+3, Co+2
Examples of basic ions
Conjugate bases of weak acids: F+, NO2-, SO3-, C2H3O2-, CN-, CO3 2-Anions of strong bases: H-, OH-, O 2-
Strong bases
LiOH, NaOH, KOH, Ca(OH)2 Calcium hydroxideIonic compounds with OH- ionUnidirectional, all of it goes to the other side
Why is NH4Cl is acidic?
When NH4+ splits apart in water it produces NH3 and H+. NH3 is a weak base and because it releases H+, increases in H+ concentration lead to lowered pH.
Lewis Acids
Electron pair acceptor
Lewis bases
Electron pair donor
What is the equilibrium going to do if you remove the reactant?
it will try to remake the missing component to restore equilibrium.
Le Chatelier’s principle for pressure
Pressure only affects gas. To relieve increased pressure, remove gas. Look at the total moles by adding coefficients of reactants and compare them to products. An increase in volume causes pressure to go down and the reaction goes in the direction with more gas. If the volume decreases, then the pressure increases and the reaction does in the direction with less gas.
Rules for energy input and removal.
Increase energy, adding energy, reaction goes to the side that will absorb that energy (treat it like a reactant)Decreasing energy is like taking away energy, it will cause the reaction to go in the direction that will cause the reaction to generate more energy.
What kind of solution is produced by a weak base
Weak base = acidic solution
What is the other name for sodium chloride and is it acidic, basic, or neutral?
Saline solution, it is neutral, pH of 7 like water.
What is the formula for the integrated rate law of a 0 order reaction?what is its half life equation?
Integrated rate law: [A] = -kt + [A]0Half life: [A]0 /2k
What is the formula for the integrated rate law of a 1st order reaction?What is the half life equation?
Integrated Rate Law: ln[A] = –kt + ln[A]oHalf life equation: 0.693/K (The constant)T= time
What is the formula for the integrated rate law of a 2nd order reaction? What is the half life equation?
Integrated rate law: 1/[A] = kt + 1/[A]0Half life: 1/k[A]0
What are the units of the rate?
M/s
Can 2 different substances have the same concentration, even if they have different volumes?
Yes, when substances have the same mol, they will most likely have the same concentration.
What does this mean in relation to the reaction∆ H < 0, negative or less than 0
The reaction is exothermic
What does this mean in relation to the reaction:∆ H > 0, positive or greater than 0
The reaction is endothermic
What happens if you increase the concentration of a reactant OR decrease the concentration of a product?(Current position)
Keq shifts right
What happens if you increase the concentration of a product or decrease the concentration of a reactant?(Current Position)
Keq shifts left
What direction does the Keq need to go in to decrease the amount of a reactant? Or to increase the amount of product? (Movement)
Keq needs to shift right
What direction does the Keq need to shift in order to decrease the amount of product? Or increase the amount of reactant? (Movement)
Keq needs to shift left
What analogy did Dr. Bell teach about equilibrium direction?
Pushing the pennies!
What direction does the Keq need to shift for the pressure to increase?
The direction with more mol of Gas.
What is the position of the Ka (equilibrium) for a strong acid
Too far right
What is the position of Kb (equilibrium) for a strong base
Too far left
What must be true of the steps in a reaction mechanism?
The sum of the steps must be the overall balanced equation and agree with the determined rate law
What conditions must be satisfied in order for a reaction to occur?
COLLISIONS involving enough energy to produce the reaction and the ORIENTATION of the reactants must allow for new bonds to form and make the products.
What is the slowest step in a reaction mechanism?
The rate-determining step determines the rate law for the overall reaction.
Relationship b/w pressure, temp, and volume?
Inc. temp = inc. Pressure = dec. volumeDec. temp = dec. pressure = inc. volume
