Search found 39 matches

by Roberto Gonzalez 1L
Sun Mar 17, 2019 6:06 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Spontaneous reactions
Replies: 7
Views: 684

Re: Spontaneous reactions

Gibbs free energy determines spontaneity, not enthalpy alone. However it does play a role. Using the equation ΔG= ΔH- TΔS and making a chart for positive and negative values of ΔS and ΔH should help you better determine what conditions are necessary for spontaneity of the forward reaction.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 6:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: standard cell potential and free energy
Replies: 3
Views: 113

Re: standard cell potential and free energy

While cell potential is an intensive property, gibbs free energy is an extensive property as it is dependent on the moles of electrons transferred.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 6:01 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Platinum Electrode
Replies: 2
Views: 85

Re: Platinum Electrode

If there is no conducting electrode in one of the two half reactions then you would use it as the anode/cathode.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:58 pm
Forum: Biological Examples (*DNA Structural Transitions, etc.)
Topic: Hemoglobin and Equilibrium
Replies: 2
Views: 355

Re: Hemoglobin and Equilibrium

What would be the catalyst/enzyme included in this reaction?
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:57 pm
Forum: Biological Examples (*DNA Structural Transitions, etc.)
Topic: DNA Structural Transition
Replies: 2
Views: 344

Re: DNA Structural Transition

This is the mechanism by which the body begins the process of transcription/translation and is relevant in terms of its endergonic nature.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:55 pm
Forum: Biological Examples (*DNA Structural Transitions, etc.)
Topic: Structures of the Human Body and Systems
Replies: 5
Views: 144

Re: Structures of the Human Body and Systems

The human body is an indeed an open system as the heat produced by our body is given off continuously, as we take in resources.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:54 pm
Forum: Van't Hoff Equation
Topic: Test #2
Replies: 5
Views: 162

Re: Test #2

The key here is to use the Van't Hoff Equation to find K2 at the temperature 30 celsius. I got 1.471^-14. Then take the square root of Kw to solve for your hydronium concentration and take the -log of the value. This will result in your new neutral pH. Comparing to see wether 7 is larger (meaning ba...
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:48 pm
Forum: Van't Hoff Equation
Topic: Temp Units
Replies: 11
Views: 185

Re: Temp Units

^Kelvin would be the units used, however if you get confused just remember that the gas constant R in the Van't Hoff Eq has units of J/K *mol.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:46 pm
Forum: Van't Hoff Equation
Topic: neutral pH not 7?
Replies: 6
Views: 139

Re: neutral pH not 7?

Kw is temperature dependent and therefore the concentration of [h30+] and [oh-], calculated by the square root of Kw, will be different.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:45 pm
Forum: Van't Hoff Equation
Topic: Constants
Replies: 3
Views: 101

Re: Constants

As the Van't Hoff Equation is used when the temperature is different for a given reaction, the change in enthalpy and entropy for the reaction remains the same as they are independent of temp and therefore t is the only variable that is different in two situations (where t1 is raised or lowered to t...
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:42 pm
Forum: Van't Hoff Equation
Topic: pH and van’t hoff
Replies: 6
Views: 140

Re: pH and van’t hoff

A neutral pH of 7 is only true for water at 25 degrees celsius. As the temperature changes, Kw changes and therefore as [h30+] is calculated by taking the square root of Kw, the neutral pH value will differ accordingly.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:40 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: U=0
Replies: 6
Views: 137

Re: U=0

Yes, for ideal gases; reversible expansion the total change in internal energy should be 0 while q and w are the ones that vary depending on the situation.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:37 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: DeltaU = 3/2 nRT
Replies: 3
Views: 117

Re: DeltaU = 3/2 nRT

This correct for monoatomic molecules while the diatomic molecule formula U=5/2 nRT
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:35 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Q6 on the midterm
Replies: 3
Views: 92

Re: Q6 on the midterm

Being that the total number of moles of gas increased, the reaction is doing work.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:33 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Heat and Entropy
Replies: 2
Views: 78

Re: Heat and Entropy

If we are considering Entropy for a phase change or heating up a substance, the same should apply assuming the same conditions.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:31 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: free expansion
Replies: 2
Views: 82

Re: free expansion

For free expansion there is no acting external pressure as it is in a vacuum and therefore no work being done. The insulation accounts for a lack of transfer of heat.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:30 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: w=-PdeltaW
Replies: 5
Views: 116

Re: w=-PdeltaW

When the system is under constant pressure, this equation gives you the work done by the expansion or compression of the gases. Think of a piston changing the volume of enclosed gases, as it can be derived using PV=nRT so change in moles of gas*n*R*T can also be used accordingly.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:27 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Midterm Question 6
Replies: 6
Views: 136

Re: Midterm Question 6

I used delta n*r*t to solve for work with a change of moles of 6. Which resulted in 28.58 Kj of work. Subtracted from n*enthalpy= -11512 gave me -11540 Kj
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:20 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Changes
Replies: 11
Views: 282

Re: Phase Changes

Yes, as well as understand how to incorporate the enthalpy of heating a substance as well as 3 step problems have been covered a lot.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:18 pm
Forum: Phase Changes & Related Calculations
Topic: Isothermic vs. Adiabatic
Replies: 3
Views: 99

Re: Isothermic vs. Adiabatic

They pertain to solving for change in U, as in Isothermic conditions there is no change in temp. but work is done equivalent to -q which is the change in U. For adiabatic conditions there is no heat transferred. Basically under both conditions keep in mind that q=0.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:13 pm
Forum: Phase Changes & Related Calculations
Topic: rotational v vibrational energy
Replies: 5
Views: 159

Re: rotational v vibrational energy

Vibrational energy is the energy that arises from atoms moving along a axis (ie: within a bond). Rotational energy is the energy that arises from a molecule rotating around an axis (can be thought of as a molecules ability to rotate about its position)
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Partial Pressure
Replies: 4
Views: 106

Re: Partial Pressure

Pure solids and liquids should be excluded from the partial pressure equilibrium constant calculations.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 5:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Midterm Q3-C
Replies: 4
Views: 101

Re: Midterm Q3-C

Given that pKa=10 , and that it is a weak acid, an amount x is ionized so there is an x amount of hydronium. However being that HA is a weak acid the amount ionized is very small compared to [HA] therefore it cannot equal [H30+].
by Roberto Gonzalez 1L
Sun Mar 17, 2019 4:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Effect of increased concentration on equilibrium
Replies: 9
Views: 271

Re: Effect of increased concentration on equilibrium

The reaction would compensate by forming more products and therefore shift to the right.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 4:57 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Equation
Replies: 8
Views: 150

Re: Equation

Correct, if we assume A=1, it should cancel out in the derivation for this condition.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 4:54 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Plot of Arrhenius function
Replies: 4
Views: 102

Re: Plot of Arrhenius function

Using the information of given in Arrhenius function should we be able to get the plot of the rate law?
by Roberto Gonzalez 1L
Sun Mar 17, 2019 4:52 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: pKa vs. pH
Replies: 15
Views: 273

Re: pKa vs. pH

pH can be solved for by taking the -log of the concentration of hydronium ions, and therefore quantitatively describes the acidity or basicity of a solution. pKa is found taking the -log of the ionization constant of an acid, and can therefore be used to understand the strength of an acid.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 4:49 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature and Le Chatlier's Principle
Replies: 6
Views: 101

Re: Temperature and Le Chatlier's Principle

If a reaction is exothermic, a rise in temperature will shift the system in favor of the products (i.e: to the left), if it is exothermic the system will shift in favor of the reactants (i.e: the right). This is due to the fact that higher temperatures will favor the direction with higher energy.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 4:45 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Effects of Compression
Replies: 5
Views: 128

Re: Effects of Compression

Yes, using Le Chatelier's principles this can be concluded as compression would result in a shift to the side of the reaction with less moles whereas expansion would shift to the side with a larger amount of moles.
by Roberto Gonzalez 1L
Sun Mar 17, 2019 4:41 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Adding an Inert Gas
Replies: 4
Views: 103

Re: Adding an Inert Gas

Adding an Inert gas does not actually cause the system to shift to either side as it does not take part in the chemical reaction.
by Roberto Gonzalez 1L
Sun Nov 04, 2018 11:59 pm
Forum: Trends in The Periodic Table
Topic: Ranking of effects on Periodic trends
Replies: 1
Views: 53

Re: Ranking of effects on Periodic trends

I had the same question of overlapping trends, however I think if you take into account the strength of say the effective nuclear charge, as compared with the removal or addition of electrons it reveals itself.
by Roberto Gonzalez 1L
Sun Nov 04, 2018 11:56 pm
Forum: Lewis Structures
Topic: Steps for Lewis Structures
Replies: 3
Views: 67

Re: Steps for Lewis Structures

Is it necessary to write formal charges at all times? Or only when explicitly told to do so? Also, for resonance structures is a hybrid resonance structure always expected if there are in fact delocalized double or triple bonds?
by Roberto Gonzalez 1L
Sun Nov 04, 2018 11:52 pm
Forum: Ionic & Covalent Bonds
Topic: electronegativity difference
Replies: 4
Views: 82

Re: electronegativity difference

If the difference in electronegativity of a molecule falls between 2 and 1.5 would it be necessary to classify said bond as a covalent bond with ionic characteristics or would it simply be a covalent bond?
by Roberto Gonzalez 1L
Sun Oct 14, 2018 11:29 pm
Forum: DeBroglie Equation
Topic: detectability of waves
Replies: 4
Views: 85

Re: detectability of waves

I had understood it was at x10^-12 m as that was the wavelength of an electron in an atom, however I'm not entirely certain
by Roberto Gonzalez 1L
Sun Oct 14, 2018 11:26 pm
Forum: Properties of Electrons
Topic: 7th Edition HW 1E.9
Replies: 2
Views: 70

Re: 7th Edition HW 1E.9

I started by converting the units of mass of the baseball from ounces to grams, and then substituting the given values into the De Broglie equation.
by Roberto Gonzalez 1L
Fri Oct 12, 2018 12:39 am
Forum: Significant Figures
Topic: significant figures
Replies: 5
Views: 290

Re: significant figures

Lets say I'm multiplying a value like (225.099) times a constant such as the speed of light (3.00x10^8). Do I simply use three significant figures because of the constant?
by Roberto Gonzalez 1L
Fri Oct 05, 2018 9:47 am
Forum: SI Units, Unit Conversions
Topic: formula units [ENDORSED]
Replies: 68
Views: 21921

Re: formula units [ENDORSED]

The "formula units" phrasing throws me off a bit for a question where I am trying to find the "formula units of compound" in a certain amount of grams. Do I just set it up as conversion from grams to moles using molecular weight and solve for the moles of the compound as a whole?
by Roberto Gonzalez 1L
Fri Oct 05, 2018 9:40 am
Forum: Significant Figures
Topic: Scientific Notation
Replies: 7
Views: 118

Re: Scientific Notation

I had the same problem of not knowing when scientific notation is actually required. More specifically if its neccesary to do all our work in this form or can I use decimals up until reaching the final solution?
by Roberto Gonzalez 1L
Fri Oct 05, 2018 9:12 am
Forum: General Science Questions
Topic: Common ions
Replies: 4
Views: 164

Re: Common ions

Something that really helps me is having a piece of paper on which I have all the info regarding common ions, (name, symbols/formulas) to reference while studying and doing homework. Over time you'll become more familiarized the more you use them, but it helps to have that as a reiteration.

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