Search found 42 matches

by vicenteruelos3
Fri Mar 16, 2018 12:27 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Activation energy and temp
Replies: 3
Views: 105

Activation energy and temp

Does activation energy change with temperature?
by vicenteruelos3
Mon Mar 12, 2018 8:39 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Adiabatic System
Replies: 3
Views: 266

Re: Adiabatic System

also, there is no transfer of matter between the system and the surroundings
by vicenteruelos3
Mon Mar 12, 2018 8:24 pm
Forum: *Enzyme Kinetics
Topic: Catalyst
Replies: 6
Views: 357

Re: Catalyst

Catalysts are not consumed so in the steps of the reaction, the species that is used as a reactant in one step, and comes out as a product in a future step is the catalyst
by vicenteruelos3
Mon Mar 12, 2018 8:14 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: reaction profile
Replies: 3
Views: 103

Re: reaction profile

maybe it could be possible if the potential gibbs free energy of the reactants is equal to the potential gibbs free energy of the products. but it is probably super rare
by vicenteruelos3
Wed Mar 07, 2018 10:57 pm
Forum: General Rate Laws
Topic: Timing of rate laws
Replies: 2
Views: 79

Re: Timing of rate laws

it at the beginning so we use the initial rate because any rate after could be affected by products going back to reactants
by vicenteruelos3
Wed Mar 07, 2018 10:50 pm
Forum: Second Order Reactions
Topic: Second Order
Replies: 3
Views: 227

Re: Second Order

false because the rate is dependent on the concentration of the reaction
r=k[A]^2
so if you change [A] then the rate also changes
by vicenteruelos3
Wed Mar 07, 2018 10:47 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Rate Law being affected by product [ENDORSED]
Replies: 2
Views: 167

Re: Rate Law being affected by product [ENDORSED]

experimentally we usually only consider the forward reaction. the example in the book with the reaction with ozone and O2, they consider the reverse reaction because in the atmosphere there is no way to isolate the products so the products are able to turn back into reactants and affect the rate law
by vicenteruelos3
Fri Mar 02, 2018 10:44 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: How to tell difference btwn thermo and kinetics [ENDORSED]
Replies: 7
Views: 243

Re: How to tell difference btwn thermo and kinetics [ENDORSED]

all reactions have to overcome a specific activation energy this is what determines the rate of the reaction (kinetics)
whether or not the products are in a higher or lower energy state than the reactants determines if the reaction is favorable (thermodynamics)
by vicenteruelos3
Fri Mar 02, 2018 10:38 pm
Forum: Second Order Reactions
Topic: Example?
Replies: 4
Views: 130

Re: Example?

another example is the decomposition of nitrogen dioxide

2NO2(g)-->2NO(g)+O2(g)

r= k[NO2]^2
by vicenteruelos3
Fri Mar 02, 2018 10:30 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Number of steps to reach the overall reaction
Replies: 3
Views: 106

Re: Number of steps to reach the overall reaction

yes since each step is a reaction and all the steps together form the overall reaction, the number of steps is equal to the number of intermediate reactions
by vicenteruelos3
Tue Feb 20, 2018 7:29 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test 2
Replies: 1
Views: 66

Test 2

Will we be given the table with the reduction half reaction potentials?
by vicenteruelos3
Sat Feb 17, 2018 11:42 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: notation for galvanic cell
Replies: 2
Views: 67

Re: notation for galvanic cell

a vertical line represents an interface between phases in contact with each other
while a comma represents two different things not separated by anything
by vicenteruelos3
Sat Feb 17, 2018 11:39 pm
Forum: Balancing Redox Reactions
Topic: Sign of E when anode rxn reverses
Replies: 2
Views: 103

Re: Sign of E when anode rxn reverses

if you use the equation Ecell= Ecathode - E anode then you dont have to switch the sign from the table

if you use the equation E cell= Ecathod + E anode then you do have to switch the sign from the table
by vicenteruelos3
Sat Feb 17, 2018 11:30 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.13 b
Replies: 1
Views: 65

Re: 14.13 b

you use an inert conductor as the electrode when dealing with half reactions that have no conducting solids.
because I2(s) is not a conductor, you use platinum as the electrode
by vicenteruelos3
Sun Feb 11, 2018 10:56 pm
Forum: Van't Hoff Equation
Topic: Different versions of van't Hoff
Replies: 2
Views: 188

Re: Different versions of van't Hoff

The advantage to using Lavelle’s is that you can calculate k at different temperatures if delta h is known
by vicenteruelos3
Sun Feb 11, 2018 9:44 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: 9.47
Replies: 1
Views: 91

9.47

why is change in entropy surroundings equal to 0 for irreversible free expansion but not for reversible?
by vicenteruelos3
Sat Feb 03, 2018 3:44 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Difference between deltaS(tot), deltaS and deltaS(surr)
Replies: 5
Views: 127

Re: Difference between deltaS(tot), deltaS and deltaS(surr)

one relation is that delta s of the system plus delta s of the surroundings is equal to delta s total
by vicenteruelos3
Sat Feb 03, 2018 3:43 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Formula Manipulations
Replies: 1
Views: 88

Re: Formula Manipulations

q is equal to deltaU at constant volume becuase delta u = q plus w, so at constant volume there is no expansionary work (w=0)
by vicenteruelos3
Sat Feb 03, 2018 3:39 pm
Forum: Van't Hoff Equation
Topic: How to calculate K [ENDORSED]
Replies: 3
Views: 260

Re: How to calculate K [ENDORSED]

to isolate k you would do e^lnk

and for the other side of the equation e^....
by vicenteruelos3
Sun Jan 21, 2018 9:47 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Bomb calorimeter
Replies: 7
Views: 217

Bomb calorimeter

Why is a bomb calorimeter an isolated system?
by vicenteruelos3
Sun Jan 21, 2018 6:40 pm
Forum: Phase Changes & Related Calculations
Topic: Delta H Fusion / Delta H Vaporization
Replies: 2
Views: 161

Re: Delta H Fusion / Delta H Vaporization

the q = n C deltaT is for molar heat capacity
by vicenteruelos3
Sun Jan 21, 2018 6:29 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimetry Questions
Replies: 2
Views: 82

Re: Calorimetry Questions

the heat absorbed by the calorimeter is equal to the heat released by the reaction
by vicenteruelos3
Sun Jan 21, 2018 6:21 pm
Forum: Phase Changes & Related Calculations
Topic: Heating Curve Calculation Confusion
Replies: 3
Views: 147

Re: Heating Curve Calculation Confusion

it depends on the starting temperature of the ice and the final temperature of the water vapor if the starting temp of ice is less than 0 and the final temp of water vapor is over 100 degrees celcius then you would use MCdeltaT three times once to go from <0 to 0, phase change, then to go from 0 to ...
by vicenteruelos3
Fri Jan 12, 2018 2:18 pm
Forum: Phase Changes & Related Calculations
Topic: qv vs qp
Replies: 4
Views: 475

qv vs qp

What is the difference between qv and qp?
by vicenteruelos3
Fri Jan 12, 2018 2:15 pm
Forum: Phase Changes & Related Calculations
Topic: Standard Reaction Enthalpy
Replies: 8
Views: 234

Re: Standard Reaction Enthalpy

One difference is that standard reaction enthalpy is in KJ, while standard enthalpy of formation is in KJ/mol
by vicenteruelos3
Fri Jan 12, 2018 2:13 pm
Forum: Phase Changes & Related Calculations
Topic: Heating Curve
Replies: 6
Views: 220

Re: Heating Curve

On the heating curve, the sloped lines represent heat capacity
by vicenteruelos3
Wed Nov 29, 2017 6:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.53 sig figs
Replies: 1
Views: 122

11.53 sig figs

a reaction mixture that consists of .400 mol H2 and 1.60 mol I2 was introduced into a 3.00 Liter flask and heated. at equilibrium, 60.0% of the hydrogen gas had reacted. what is the equilibrium constant K for the reaction.

why is the answer in 2 sig figs?
by vicenteruelos3
Tue Nov 28, 2017 1:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: t-shaped
Replies: 4
Views: 227

Re: t-shaped

one bond angle is also slightly less than 120 degrees
by vicenteruelos3
Tue Nov 28, 2017 1:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Internuclear Axis
Replies: 1
Views: 109

Re: Internuclear Axis

yes it is the area where electrons are being shared. it is just the imaginary straight line that connects the nuclei of atoms bonded to each other in a molecule
by vicenteruelos3
Thu Nov 09, 2017 11:39 am
Forum: Bond Lengths & Energies
Topic: dissociatioin energies
Replies: 3
Views: 221

Re: dissociatioin energies

oh i think i meant to say NH

so why is dissociation energy of CH higher than that of NH
by vicenteruelos3
Thu Nov 09, 2017 1:41 am
Forum: Bond Lengths & Energies
Topic: dissociatioin energies
Replies: 3
Views: 221

dissociatioin energies

why does CH have a higher dissociation energy than CN
by vicenteruelos3
Wed Nov 01, 2017 11:35 pm
Forum: Electronegativity
Topic: oxygen and nitrogen
Replies: 3
Views: 283

oxygen and nitrogen

why is oxygen and nitrogen switched for ionization energy and not for electronegativity if electonegativity is based on ionization energy??
by vicenteruelos3
Wed Nov 01, 2017 11:28 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Wave Function
Replies: 2
Views: 176

Re: Wave Function

you would use the wave function to describe an electron with wavelike properties and indeterminacy in momentum and position in an atom. it is also the radial wavefuntion times the angular wave function. this shows how orbitals change with angles and radii
by vicenteruelos3
Wed Nov 01, 2017 11:23 pm
Forum: Trends in The Periodic Table
Topic: 2.71
Replies: 1
Views: 140

Re: 2.71

oxidation state is referring to the charge. a plus 4 charge is at a higher oxidation state than a plus 3 charge
by vicenteruelos3
Sun Oct 29, 2017 6:09 pm
Forum: Electronegativity
Topic: Exceptions [ENDORSED]
Replies: 2
Views: 150

Re: Exceptions [ENDORSED]

oxygen and nitrogen are exceptions to the trend for ionization energy, not for electronegativity. we expect oxygen to have higher IE than nitrogen but nitrogen has higher IE. this is because of the p orbital. oxygen has 4 electrons in the p subshell, while nitrogen has 3. because nitrogen has 3 elec...
by vicenteruelos3
Sun Oct 29, 2017 5:57 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge of Carbon in CH3
Replies: 2
Views: 767

Re: Formal Charge of Carbon in CH3

the formal charge of carbon in ch3 is 0.
valence electron=4
lone electrons=1
bonded electrons/2=3

4-(1+3)=0
FC=0
by vicenteruelos3
Sun Oct 29, 2017 5:50 pm
Forum: Ionic & Covalent Bonds
Topic: Noble Gases
Replies: 6
Views: 366

Re: Noble Gases

because noble gases have very high ionization energy and very low electron affinity, they do not form chemical compounds easily. however when they are ionized or under pressure, they are able to make chemical compounds. so, yes they can make chemical compounds even tho they have a full outer shell
by vicenteruelos3
Fri Oct 13, 2017 6:59 pm
Forum: Photoelectric Effect
Topic: Photoelectric Post Assessment Module 30C
Replies: 4
Views: 247

Re: Photoelectric Post Assessment Module 30C

you can use the equation

frequency= (.5 x mass of electron x velocity of electron squared +work function) /plancks constant

i got that from
Energy of photon - work function = kinetic energy of electron
energy of photon = h x frequency
and
KE = .5mv^2
by vicenteruelos3
Fri Oct 13, 2017 5:00 pm
Forum: Photoelectric Effect
Topic: Post Assessment #28 [ENDORSED]
Replies: 4
Views: 238

Re: Post Assessment #28 [ENDORSED]

yes, the energy required to remove an electron is equal to the work function or threshold energy
by vicenteruelos3
Fri Oct 06, 2017 10:22 am
Forum: Molarity, Solutions, Dilutions
Topic: G13 [ENDORSED]
Replies: 2
Views: 249

Re: G13 [ENDORSED]

to find the concentration after the dilution you use (M initial)(volume initial) = (molarity final)(volume final)
(.2 x 1)/(4) = final molarity

that equals .05M
you use 4 because its final volume in the equation
by vicenteruelos3
Thu Oct 05, 2017 8:26 pm
Forum: Balancing Chemical Reactions
Topic: incomplete combustion
Replies: 3
Views: 271

incomplete combustion

this isn't one of the homework problems, but question H.18 asks what the chemical equation is for the incomplete combustion of heptane gas. i was just wondering how to do it??

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