Search found 49 matches
- Sun Mar 18, 2018 12:14 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Collision Theory
- Replies: 5
- Views: 711
Re: Collision Theory
collisions are more likely when the reactants meet at the right orientation and with enough energy. increasing the temperature helps satisfy the need for more molecules of reactant colliding with enough energy
- Sun Mar 18, 2018 12:12 am
- Forum: *Enzyme Kinetics
- Topic: Enzymes
- Replies: 8
- Views: 1671
Re: Enzymes
the most basic understanding is that enzymes make the reaction faster by providing a different pathway in which the activation energy is lower
- Sun Mar 18, 2018 12:10 am
- Forum: *Enzyme Kinetics
- Topic: Catalyst and equilibrium constant
- Replies: 3
- Views: 2754
Re: Catalyst and equilibrium constant
the equilibrium constant does not change but the k that is the rate constant does change
- Mon Mar 05, 2018 2:10 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Bimolecular Reactions [ENDORSED]
- Replies: 2
- Views: 431
Re: Bimolecular Reactions [ENDORSED]
bimolecular refers to any two molecules interacting
whether it be A + A or A+B
whether it be A + A or A+B
- Mon Mar 05, 2018 2:09 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Which Step is Slower?
- Replies: 8
- Views: 891
Re: Which Step is Slower?
The slow step is also the step with the largest activation energy
- Mon Mar 05, 2018 2:08 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Assuming Elementary Rxn [ENDORSED]
- Replies: 2
- Views: 365
Re: Assuming Elementary Rxn [ENDORSED]
We didn't just assume that it was the elementary step. He gave us the rate law initially and because the rate law is solely dependent on the slow step, you can determine which of the elementary steps is the slow step by matching that steps rate law to the rate law that was given initially
- Sun Feb 18, 2018 8:28 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing
- Replies: 3
- Views: 590
Re: Balancing
yes you do in both acidic and basic solutions
- Sun Feb 18, 2018 8:25 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: cell potential equations
- Replies: 3
- Views: 620
Re: cell potential equations
depending on your calculator, you might have to put in log with a base of 10 explicitly since some calculators imply that base while others dont
- Sun Feb 18, 2018 8:23 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: equilibrium
- Replies: 3
- Views: 458
Re: equilibrium
it would be 0 because ∆G would be 0
- Sun Feb 18, 2018 8:22 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Concentration Cells
- Replies: 3
- Views: 696
Re: Concentration Cells
You need the difference in concentration so that in order for the reaction to be spontaneous, the electrons that are lost in the anode must move to the cathode. Therefore, the reactants must have a larger concentration so that the reaction in the anode takes place so that the electrons move from the...
- Sun Feb 18, 2018 8:20 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Concentration
- Replies: 3
- Views: 559
Re: Concentration
the higher the concentration of products, the higher the value of Q, the more negative the value of Ecell, and therefore the reaction it is un-spontaneous the higher the concentration of reactants, the lower the value of Q, the more positive the value of Ecell, and therefore the reaction is spontane...
- Sun Feb 18, 2018 8:18 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Standard Cell Potentials
- Replies: 5
- Views: 515
Re: Standard Cell Potentials
yes it is because potentials are intensive properties
- Sun Feb 18, 2018 8:17 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic Cells 14.3
- Replies: 2
- Views: 352
Re: Galvanic Cells 14.3
If the reaction takes place in a cell that performs electrical work, then the heat released is diminished by the amount of electrical work done.
- Sun Feb 18, 2018 8:15 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum electrodes
- Replies: 4
- Views: 553
Re: Platinum electrodes
platinum electrodes are used when there are no metal solids or only one metal solid. a platinum electrode is not required when BOTH the anode and cathode reactions contain solid metals
- Sun Feb 18, 2018 8:12 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: inert metals
- Replies: 1
- Views: 258
inert metals
Is there a specific inert metal that must be used in certain reactions or can we generalize it and use any inert metal?
- Sun Feb 18, 2018 8:10 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagrams
- Replies: 3
- Views: 439
Re: Cell Diagrams
They will be written in the way the reaction takes place so the direction does matter
- Mon Feb 05, 2018 11:43 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 9.35?
- Replies: 2
- Views: 487
Re: 9.35?
there is an error and C should have the greatest entropy because it has both vibrational and rotational energy
- Mon Feb 05, 2018 11:40 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 9.31d
- Replies: 1
- Views: 228
Re: 9.31d
it's not always the same, it depends on the different energies like rotational, etc.
- Mon Feb 05, 2018 11:35 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 9.85
- Replies: 2
- Views: 591
Re: 9.85
a) a positive enthalpy would result in the dissolving to be unfavorable because a positive enthalpy would result in a positive ∆G value and a negative enthalpy would result in the dissolving to be favorable because a negative enthalpy would result in negative ∆G.
- Tue Jan 30, 2018 9:44 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Perfect Crystal in terms of Entropy
- Replies: 2
- Views: 263
Re: Perfect Crystal in terms of Entropy
in addition, Dr. Lavelle mentioned in lecture that an entropy=0 can only occur when the temperature is at 0 K.
- Tue Jan 30, 2018 9:42 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: heat capacity and entropy
- Replies: 2
- Views: 635
Re: heat capacity and entropy
the entropy increases because a higher heat capacity means that more energy will be needed to increase that substances temperature by 1 Celsius. That extra energy needed is transferred to the substances atoms and molecules and increase their energy. This increase in energy can result in an increase ...
- Tue Jan 30, 2018 9:38 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Cv vs. R
- Replies: 1
- Views: 309
Cv vs. R
I was looking through the solutions manual and noticed that it uses Cv and R interchangeably for some problems involving ideal gases. Why can is it that this can happen?
- Mon Jan 22, 2018 11:13 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: self test 8.7B
- Replies: 2
- Views: 352
Re: self test 8.7B
the answers for the B portions of the self test questions can be found in the back of the book under answers> self-test B
- Mon Jan 22, 2018 11:10 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Constant Volume vs Constant Pressure
- Replies: 2
- Views: 344
Re: Constant Volume vs Constant Pressure
to add onto the previous post,
the actual q equations are the same, you only need to change the value of the specific heat to reflect that of a system under constant pressure or constant volume
q=nCp∆T
or
q=nCv∆T
the actual q equations are the same, you only need to change the value of the specific heat to reflect that of a system under constant pressure or constant volume
q=nCp∆T
or
q=nCv∆T
- Mon Jan 22, 2018 11:06 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 8.99 Negative Specific Heat Capacity
- Replies: 3
- Views: 465
Re: 8.99 Negative Specific Heat Capacity
If you put your final answer in Celcius, it is possible that hte temperature could be negative, indicating that is lost heat
- Tue Jan 16, 2018 8:14 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Problem 8.65
- Replies: 2
- Views: 333
Re: Problem 8.65
that is the reaction you want because that forms one mole of N2O5 and the equation asks for the enthalpy of formation for N2O5 and that refers to the amount of energy needed for one mole of N2O5 when it is formed by elements in their natural form. the purpose of the reaction you mentioned is to allo...
- Tue Jan 16, 2018 8:10 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Chapter 8 8.57
- Replies: 1
- Views: 231
Re: Chapter 8 8.57
you would write out the combustion analyses for each molecule and manipulate the equations and enthalpy values in a way so that you end up with the equation provided when all 3 combustion reactions are added together. you would write the combustion reaction for H2 without it forming CO2. yes, the eq...
- Tue Jan 16, 2018 8:04 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Heat Capacities
- Replies: 6
- Views: 343
Re: Heat Capacities
the molar heat capacity is the amount of heat needed to raise the temperature of 1 mole of a substance by 1 degree Celsius or 1 kelvin.
the specific heat capacity is the amount of heat needed to raise the temperature of 1 gram of a substance by 1 degree celsius or 1 kelvin
the specific heat capacity is the amount of heat needed to raise the temperature of 1 gram of a substance by 1 degree celsius or 1 kelvin
- Tue Jan 16, 2018 7:56 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 8.19
- Replies: 2
- Views: 299
Re: 8.19
the q values for the water and the copper are added in the solution manual because no heat is technically being lost. Instead, heat is simply being transferred into the kettle and then into the water. Because of this, there is no loss in heat in either kettle nor the copper, meaning that no negative...
- Wed Jan 10, 2018 9:25 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 8
- Views: 1391
Re: Hess's Law
They will always cancel each other out because hess’s Law is just a representation of steps that give the final output. Therefore, if some didn’t cancel out, there would be a different number of products
- Wed Jan 10, 2018 9:21 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy of Freezing
- Replies: 4
- Views: 1656
Re: Enthalpy of Freezing
That is correct but the negative is arbitrary since it depends on the direction of the phase change
- Wed Jan 10, 2018 9:20 pm
- Forum: Phase Changes & Related Calculations
- Topic: chapter 8
- Replies: 6
- Views: 594
Re: chapter 8
Yes he is started with the second half which is section 10 to section 20
- Wed Nov 29, 2017 1:30 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Concept Question
- Replies: 3
- Views: 548
Re: Concept Question
it's all based on the ratios so in order to increase the yield of ammonia, you need to decrease ammonia (take some out) because then the ratio will heavily favor the reactants. for example if at equilibrium the ratio of reactants to products is 2:2 so when you remove the ammonia, the ratio becomes 2...
- Wed Nov 29, 2017 1:27 am
- Forum: Ideal Gases
- Topic: 11.7 Part a
- Replies: 3
- Views: 541
Re: 11.7 Part a
If you look at the question, it says that the flasks show dissassociation over time. Therefore, you must pick the flask that has no more change by looking at the next flask. You see this occur at flask 3 as in flask 4 there is no change. However in addition to this you have to make sure that the co...
- Wed Nov 29, 2017 1:26 am
- Forum: Ideal Gases
- Topic: Units for the formula
- Replies: 4
- Views: 763
Re: Units for the formula
you should note that the values of R with both the pressure in atm and bar are given values on the constants sheet
- Wed Nov 29, 2017 1:23 am
- Forum: Ideal Gases
- Topic: 11.7 Part C
- Replies: 2
- Views: 433
Re: 11.7 Part C
they use that equation because in order to determine partial pressures, you need to look at the number of moles of each gas atom or molecule within the closed volume since the number of moles of gas will determine how the reaction changes as it approaches equilibrium or how the reaction will react i...
- Wed Nov 29, 2017 1:21 am
- Forum: Ideal Gases
- Topic: Pascal vs Atmosphere
- Replies: 3
- Views: 774
Re: Pascal vs Atmosphere
Lavelle does prefer atm however you need to double check what the original units are for the partial pressure given and match those units. if no units are given but an R (gas constant) value is given, double check to see whether that value of R represents the pressure in atm or bar.
- Wed Nov 29, 2017 1:19 am
- Forum: Hybridization
- Topic: general hybridization
- Replies: 2
- Views: 292
Re: general hybridization
all you need to do is count the areas of electron density and add them. for example, 2 areas of high electron density would be sp, 3 would be sp^2, 4 would be sp^3, 5 would be sp^3d, and 6 would be sp^3d^2
- Wed Nov 29, 2017 1:16 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Dipole moments
- Replies: 2
- Views: 459
Re: Dipole moments
put succinctly, you need to look at the geometry of the bond and the electronegativity of the atoms within the compound in order to determine whether dipole moments do or do not cancel out
- Thu Nov 09, 2017 11:55 am
- Forum: Dipole Moments
- Topic: Polarity
- Replies: 5
- Views: 864
Re: Polarity
In addition to the posts above, if you would like to get a general sense as to whether a molecule is polar or not, you can also compare the relative electronegativity of each of the atoms that occupy it. If the difference in their electronegativity is great (based on periodic trends), then you can a...
- Thu Nov 09, 2017 11:52 am
- Forum: Dipole Moments
- Topic: Finding Dipole Moments
- Replies: 3
- Views: 722
Re: Finding Dipole Moments
To continue on with the previous post, when looking at the most electronegative element, however, you have to look at it in comparison to the other atom. This means that you need to see if there is a significant difference in electronegativity between the two elements
- Sun Nov 05, 2017 11:57 pm
- Forum: Lewis Structures
- Topic: Problem 3.59 Part A
- Replies: 4
- Views: 605
Re: Problem 3.59 Part A
The ion is able to exist only because the extra electron becomes part of another bond
- Sun Nov 05, 2017 11:56 pm
- Forum: Lewis Structures
- Topic: 3.25 part d
- Replies: 2
- Views: 272
Re: 3.25 part d
Hydrogen can act as a cation because of its low ionization energy
- Wed Oct 25, 2017 11:02 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Energy level for n=3 and n=4?
- Replies: 3
- Views: 1419
Re: Energy level for n=3 and n=4?
The 3d sub shell is higher than 4s when the 4s subshell is full but the 3d subshell is completely empty. However, the minute that 3d gains an electron, the 4s subshell becomes the higher energy subshell.
- Wed Oct 25, 2017 10:56 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: HW Question 2.43
- Replies: 4
- Views: 610
Re: HW Question 2.43
The answer is correct because when you put [Xe] you are saying that the electron configuration already consists of the electron configuration for Xe
- Thu Oct 19, 2017 11:36 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: 1.6b
- Replies: 2
- Views: 409
Re: 1.6b
make sure that when you're calculating it using the bohr relationship that you convert the values into kilograms and m/s before you calculate the wavelength.
- Thu Oct 19, 2017 11:33 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg Uncertainty Equation
- Replies: 7
- Views: 715
Re: Heisenberg Uncertainty Equation
You can expect the uncertainty to be greater for an electron because an electron has a smaller mass, and since mass is inversely proportional to velocity, would have a greater speed and momentum in comparison to the marble
- Thu Oct 05, 2017 10:48 pm
- Forum: Significant Figures
- Topic: E29 (d) Significant Figures
- Replies: 3
- Views: 480
Re: E29 (d) Significant Figures
The number of sig figs only depends on the original number of sig figs in the original values given. So you simply have to look back at the original values, but don't forget to take into consideration the fact that the rules for addition and subtraction can affect that value.
- Thu Oct 05, 2017 10:43 pm
- Forum: Limiting Reactant Calculations
- Topic: Reactant vs. Reagent [ENDORSED]
- Replies: 23
- Views: 34400
Re: Reactant vs. Reagent [ENDORSED]
While they may have different definitions, when they are used in a question, the two terms can essentially be used interchangeably.