reactivity
for each phase change, indicate what it's changing from and if energy is absorbed or released.
melting, freezing, evaporating, condensing, sublimating, depositing
melting- solid to liquid-energy absorbed
freezing - liquid to solid- energy released
evaporating- liquid to gas- energy absorbed
condensing- gas to liquid- energy released
sublimating- solid to gas - energy absorbed
depositing - gas to solid- energy released
remember gas has higher energy than liquid and then solid. If it's transitioning from a high energy phase like gas to a low energy phase like liquid, then energy is being RELEASED. If vice versa, it's being absorbed to get to that high energy state.
1. what are the conversion factors for molecules, liters, and grams?
2. how do you find the leftovers, and how many grams of something can be produced?
molecules: 6.022 x 10^23, liters = 22.7, g = convert by molar mass
1. convert reactants to product, the lowest g or mols (depending on question) gives you the limiting reactant and how much can be produced. to find leftover, convert the LR TO ER, and then subtract that from the given amount.
ex. 56.0g ER equal 37.7 g ER, you were given 56.0 g ER, so you subtract 56.0 by 37.7
what is the relationship between fraction of particles and molecular speed?
2. what is the formula for kc? (equillibrium constant), what is the relationship between kc and temperature (it differs between exo and endothermic reactions)?
1. when the molar mass of the gas is high, there will be a higher fraction of particles at low moleculer speeds (and vice versa)
2. KC = [products / [reactants]
exothermic = kc decrease when temp increase, kc increase when temp decrease
opposite relationships
endothermic = kc increase when temp increase, kc decrease when temp decrease
what is the arrhenius definition of an acid and base?
bronsted lowry definition?
arrhenius:
Acid - increases the concentration of H3O+ when dissolved in water base- increased the concentration of OH when disolved in water ex. NaOH -> Na+ + OH-
bronsted lowry: acid- proton donator base - proton acceptor (H+)
what is important to remember about pH
its a logartihimic scale from 0-14 that measures the concentration of H+ ions in solution
the lower the number, the more concentrated the H+
every change on the pH scale is a change of a power of 10
1. endothermic = heat is ABSORBED from surrounding environment to system, positive enthalpy change, product energy > reactants
exothermic = heat is released, negative enthalpy change, reactant energy > product
1. what is % atom economy formula
2. How to find percent yield?
% atom economy = molar mass desired product/ molar mass of alll reactants x 100
2. Percent yield is actual/theoretical x 100
what does kc tell you about reactants and products?
kc > 1 = products are favored, equillibrium mixture contains mostly products
kc < 1 = reactants are favored, little product formed goes to completion = most reactants are converted into products
what to remember when finding the parent acid and salt of a base?
cation = positively charged ion
anion = negatively charged ion
cation belongs to a base (parent base) and anion belongs to an acid (parent acid)
what are the calculations / formulas for pH, poH, [H+]. [OH-]
pH = - log [H+] pOH = -log [OH-]
pH + pOH = 14 [H+] = 10^ -pH
[OH-] = 10^-pOH
lower than 7 ph = acid higher than 7= base
1. what is activation energy?
2. how to solve for enthalpy change?
3. How do you solve for bond enthalpy?
1. activation energy is minimum amount of energy required for chemical reaction to occur.
2. energy products - energy reactants
3. draw lewis dot structure of each, You use your lab data booklet (pg. 13, table 12) to find bond enthalpy of EACH bond. then solve and do REACTANT - PRODUCT
1. Name 3 main ways that rate can be measured
2. How would you calculate instaneous rate?
1. Change in volume of gas produced over time, change in mass of the reactant over time, change in concentration measured by concentration or conductivity over time.
2. Instaneous rate would be calculated by drawing a tangent line to the curve of the graph, taking two points from the graph, and plugging those points into the slope equation
slope = y2 - y1 / x2 - x1
how does equillibrium shift with temperature changes? (consider both exo and endothermic)
how does mols of gas affect equillibrium (increase in pressure?)
1. in endothermic reactions, heat is reactant, eq. shift to product.
in exothermic, heat is a product, eq. shift to reactant.
Remember: Equillibrium will shift to the opposite side to counteract added heat
equillibrium will shift to the side with fewer mols of gas if there's an increase in pressure, decrease in pressure will do the opposite (side w/ more mols of gas)
what are some strong acids that dissociate complete?
weak acids?
strong bases? weak bases?
HCL, H2SO4, HNO3, HBR, HI and HClO4
weak: HC3H3O3, HCOOH, HNO3, and H2SO3
strong base: NaOH NaOH--> Na+ OH-
weak bases: NH3
ex. NH3 + H2O --> NH4+ + OH-
what atmospheric pollutants contribute to acid deposition?
sulfur dioxide (SO2) and nitrogen oxides (NOx), they undergo chemical reactions in the atmosphere and form sulfiric acid (H2SO4) and nitric acid (HNO3)
how to find enthalpy of a reaction? list the steps.
1. write out equation
2. find the limiting reactant by covering each reactant to a product (precipitate or solid)
3. use q= mc delta t to find Q. convert Q to KJ by dividing by a 1000.
4. determine the kj/mol (of LIMITING REACTANT, not converted to the product)
temperature of solution increased = exothermic
decreased = endothermic
add a negative or positive to kj/mol
what things increase the rate of a reaction? name 3
1.) increasing the concentration (for a liquid/aq solution), higher surface area of solids (smaller pieces), high pressure (for gas)
2.) increasing the temperature
3.) adding a catalyst will lower the activation energy required for a reaction. a larger fraction of particles posess sufficient kinetic energy to overcome the enegry barrier and react
what does a ka value tell you about an acid?
what is dynamic equillibrium? what does q and kc relationship tell you about which reaction is favored?
higher ka indicates a stronger acid.
dynamic equillibrium = rate of forward reaction is equal to rate of reverse reaction (same time)
Q > kc = concentration products greater than eq., reverse reaction favored
Q < kc = concentration reactants greater than eq., forward reaction favored.
q= kc = system is at equillibrium, forward and reverse reactions at equal rates
how can you test for a strong vs. weak acid
1.) ph, strong acid = below 2, strong base =above 11
2._ reaction with a carbonate. strong acid would produce more fizzling and bubbling
3. conductivity : complete dissociating means more ions and will conduct more electricity. conductivity probe can measure
how do you find the percent by mass using a absorbance graph?
1. when an absorbance number is given, you find the molarity that corresponds to it, solve for mols, then convert mols to grams of the substance,
then divide that number by the original piece's weight x 100 = percent by mass
1. what does each part of q= mc delta t stand for?
2. what are some assumptions made when solving for enthalpy?
1. m= mass c= specific heat (4.184) delta t= change in temperature Q= Joules
2. density is 1 g/ml, specific heat is similiar to water : 4.184, the calorimeter is the perfect insulator and no heat is loss or gained to the environment. LARGEST SOURCE OF ERROR IS HEAT LOSS TO THE ENVIRONMENT
what are the fundamentals of collision theory?
what are some things to remember about the effect some changes may have on a reaction?
1. particles must collide (no more than two at a time to be effective) 2. particles must collide with the proper orientation 3. particles must collide with enough energy (Activation energy)
2. increase in concentration leads to more collisions, adding a catalyst provides an alternate reaction pathway with lower ea, increase in temp leads to more kinetic energy which leads to more collisions and more molecules have the energy to meet the activation energy.
acid and bases
1. what is binary acid, and how do you name them?
2. what is a ternary acid and how do you name?
binary = hydrogen and a non-metal
hydro + root of non metal + ic + acid ex. HCl= hydrochloric acid
Ternary acid = contains hydrogen, nonmetal and oxygen
1. most oxygen = per + root non metal + ic + acid
2. less oxygen = root of nonmetal +ic + acid
3. less oxygen = root of nonmetal + ous + acid
4. least oxygen = hypo + root of non metal + ous + acid
what is the approximate eq. point for the following reactions? and indicator used?
strong acid and strong base
strong acid and weak base
weak acid and strong base
strong acid and strong base - ph 7
strong acid and weak base- ph < 7
weak acid and strong base- ph > 7
REMEMBER TO REVIEW THE DIFFERENT ALKENES, ALKANES, ALKYNES, ETC. BEFORE THE TEST!
okay