Search found 63 matches

by Ricardo Martin 1J
Fri Mar 15, 2019 3:33 pm
Forum: General Science Questions
Topic: Standard Conditions/ Standard Temperature
Replies: 2
Views: 6

Standard Conditions/ Standard Temperature

What is the temperature in standard conditions? Is it 0 degrees C or 25 degrees C?
by Ricardo Martin 1J
Wed Feb 20, 2019 9:37 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: O2
Replies: 5
Views: 35

Re: O2

Because 02 occurs naturally.
by Ricardo Martin 1J
Wed Feb 20, 2019 9:36 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Test 3
Replies: 10
Views: 83

Re: Test 3

Yes it will cover Gibbs free energy and what we cover in lecture during week 7.
by Ricardo Martin 1J
Wed Feb 20, 2019 9:35 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gr and Gp from lecture
Replies: 2
Views: 24

Re: Gr and Gp from lecture

Yes the r in Gr corresponded to reactants and the p in Gp to products.
by Ricardo Martin 1J
Wed Feb 20, 2019 9:34 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneous vs Not Spontaneous
Replies: 7
Views: 49

Re: Spontaneous vs Not Spontaneous

Yes the reaction is only spontaneous if the free energy is negative (-).
by Ricardo Martin 1J
Wed Feb 20, 2019 9:32 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G a state function?
Replies: 23
Views: 137

Re: Delta G a state function?

Yes delta G is a state function because it is defined by other state functions.
by Ricardo Martin 1J
Wed Feb 20, 2019 9:31 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: gibbs free energy
Replies: 10
Views: 70

Re: gibbs free energy

If free energy is negative (-) then the reaction is spontaneous and if it is positive (+) then the reaction is not spontaneous (requires energy).
by Ricardo Martin 1J
Wed Feb 20, 2019 9:25 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Liquid and moles
Replies: 8
Views: 78

Re: Liquid and moles

Since H20 is a liquid it would not be used in the calculation of the equilibrium constant and ICE table.
by Ricardo Martin 1J
Wed Feb 20, 2019 9:22 am
Forum: Calculating Work of Expansion
Topic: S=0
Replies: 12
Views: 98

Re: S=0

S=0 in a perfect crystal (T= 0 Kelvin)
by Ricardo Martin 1J
Wed Feb 20, 2019 9:20 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Work done vs work on system
Replies: 18
Views: 91

Re: Work done vs work on system

When work is done BY the system w is negative and when work is done ON the system w is positive.
by Ricardo Martin 1J
Wed Feb 06, 2019 9:36 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Cup of Tea
Replies: 17
Views: 161

Re: Cup of Tea

It is open because matter and energy can be transferred in and out of it.
by Ricardo Martin 1J
Wed Feb 06, 2019 9:35 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Midterm [ENDORSED]
Replies: 48
Views: 618

Re: Midterm [ENDORSED]

I have found it helpful to do all the homework problems and attend peer learning sessions.
by Ricardo Martin 1J
Wed Feb 06, 2019 9:34 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed and Isolated
Replies: 10
Views: 64

Re: Closed and Isolated

A closed system does not allow for matter transfer, but allows for energy transfer. An isolated system does not allow for both matter and energy transfer.
by Ricardo Martin 1J
Wed Feb 06, 2019 9:30 am
Forum: Administrative Questions and Class Announcements
Topic: Equation sheet for midterm
Replies: 3
Views: 47

Re: Equation sheet for midterm

Yes, the equation sheet, constants, and periodic table are always provided for tests and exams.
by Ricardo Martin 1J
Wed Feb 06, 2019 9:28 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: pKa vs. pH
Replies: 15
Views: 121

Re: pKa vs. pH

pH is the concentration f hydrogen ions in the solution.
by Ricardo Martin 1J
Wed Feb 06, 2019 9:26 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: ICE
Replies: 19
Views: 145

Re: ICE

E stands for equilibrium concentration.
by Ricardo Martin 1J
Wed Feb 06, 2019 9:25 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: isolated vs closed system
Replies: 7
Views: 79

Re: isolated vs closed system

Isolated system does not allow for the transfer of matter or energy while a closed system can transfer energy (but not matter).
by Ricardo Martin 1J
Wed Feb 06, 2019 9:24 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units
Replies: 7
Views: 57

Re: Units

J/C(mol) - Joules over Celsius times mole(s)
by Ricardo Martin 1J
Wed Feb 06, 2019 9:20 am
Forum: Phase Changes & Related Calculations
Topic: Type of systems
Replies: 12
Views: 94

Re: Type of systems

An isolated system does not allow transfer of matter and energy.
by Ricardo Martin 1J
Wed Feb 06, 2019 9:18 am
Forum: Phase Changes & Related Calculations
Topic: Heat and Condensation
Replies: 9
Views: 63

Re: Heat and Condensation

Condensation releases heat.
by Ricardo Martin 1J
Wed Feb 06, 2019 9:17 am
Forum: Phase Changes & Related Calculations
Topic: State Function
Replies: 10
Views: 70

Re: State Function

A state function is a property that does not rely on the path taken from the initial state to the final state.
by Ricardo Martin 1J
Wed Jan 23, 2019 10:04 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q and K
Replies: 10
Views: 94

Re: Q and K

If Q > K then a reverse reaction is favored.
If Q < K then a forward reaction is favored.
by Ricardo Martin 1J
Wed Jan 23, 2019 9:55 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Acids and Bases
Replies: 6
Views: 55

Acids and Bases

How can you tell if a molecule is an acid or a base (based on its chemical formula)?
by Ricardo Martin 1J
Wed Jan 23, 2019 9:53 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5% rule
Replies: 11
Views: 85

Re: 5% rule

The 5% rule is just used to check if your approximation is valid. You can assume that you are allowed to approximate when the k value is <10^-3.
by Ricardo Martin 1J
Wed Jan 23, 2019 9:50 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Strong acids and bases
Replies: 6
Views: 58

Re: Strong acids and bases

I do not think you need to memorize because you can tell by the K value, however it would not hurt to know common strong acids and bases.
by Ricardo Martin 1J
Wed Jan 23, 2019 9:47 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Does [H3O+][OH-] always equal 10^-14?
Replies: 9
Views: 82

Re: Does [H3O+][OH-] always equal 10^-14?

It is only equal to 10^-14 when water is at 25 degrees C. However, I believe (at least so far) our reactions will be given in this condition.
by Ricardo Martin 1J
Wed Jan 23, 2019 9:44 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Removing products
Replies: 10
Views: 62

Re: Removing products

Removing products would only affect Q and K would remain unchanged.
by Ricardo Martin 1J
Sun Jan 13, 2019 7:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: equations
Replies: 10
Views: 74

Re: equations

You can find out by writing out the chemical equation.
by Ricardo Martin 1J
Sun Jan 13, 2019 7:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: True or False regarding reaction mixture [ENDORSED]
Replies: 10
Views: 69

Re: True or False regarding reaction mixture [ENDORSED]

Yes, the composition of the reaction mixture remains constant when at equilibrium.
by Ricardo Martin 1J
Sun Jan 13, 2019 7:21 pm
Forum: Student Social/Study Group
Topic: New to Lavelle
Replies: 32
Views: 486

Re: New to Lavelle

Personally, I find it helpful to do all problems assigned for homework and attending review sessions during the week and also the ones right before midterms and finals.
by Ricardo Martin 1J
Thu Dec 06, 2018 10:54 am
Forum: Hybridization
Topic: lone pairs
Replies: 20
Views: 144

Re: lone pairs

Yes, since hybridization relates to the # of areas of electron density and lone pairs are considered an area of electron density, then lone pairs are taken into consideration for hybridization.
by Ricardo Martin 1J
Thu Dec 06, 2018 10:51 am
Forum: Hybridization
Topic: tetrahedral
Replies: 5
Views: 50

Re: tetrahedral

4 areas of electron density equals sp3 hybridization.
by Ricardo Martin 1J
Thu Dec 06, 2018 10:48 am
Forum: Hybridization
Topic: Double and Triple Bonds
Replies: 17
Views: 110

Re: Double and Triple Bonds

No, they do not change the hybridization of an atom, only areas of electron density change it.
by Ricardo Martin 1J
Thu Dec 06, 2018 10:44 am
Forum: Hybridization
Topic: hybridization
Replies: 2
Views: 20

Re: hybridization

sp3 should be enough.
by Ricardo Martin 1J
Thu Dec 06, 2018 10:43 am
Forum: Hybridization
Topic: Hybridization
Replies: 11
Views: 88

Re: Hybridization

Trigonal planar is considered sp^2 hybridization because it has 3 regions of electron density.
by Ricardo Martin 1J
Thu Dec 06, 2018 10:40 am
Forum: Determining Molecular Shape (VSEPR)
Topic: polarity
Replies: 11
Views: 73

Re: polarity

If a Lewis structure is symmetric it is non-polar and if it is not symmetric it is polar.
by Ricardo Martin 1J
Thu Dec 06, 2018 10:35 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent Structures
Replies: 12
Views: 112

Re: Bent Structures

Yes bent structures are polar.
by Ricardo Martin 1J
Thu Dec 06, 2018 10:34 am
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Notation
Replies: 10
Views: 60

Re: VSEPR Notation

Ethan Breaux 1J wrote:Is VSEPR Notation also referred to as VSEPR Formula?

I believe they are the same thing.
by Ricardo Martin 1J
Thu Dec 06, 2018 10:32 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs
Replies: 11
Views: 110

Re: Lone Pairs

Lone pairs are able to repel bond pairs more than bond pairs are able to repel each other, therefore the bond angles are made smaller by lone pairs.
by Ricardo Martin 1J
Thu Dec 06, 2018 10:30 am
Forum: Determining Molecular Shape (VSEPR)
Topic: AX3E
Replies: 18
Views: 122

Re: AX3E

The electron arrangement would be tetrahedral, however since one is a lone pair the shape is trigonal pyramidal.
by Ricardo Martin 1J
Thu Dec 06, 2018 10:28 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs angular?
Replies: 15
Views: 126

Re: Bent vs angular?

Bent and angular are the same shape
by Ricardo Martin 1J
Thu Dec 06, 2018 10:25 am
Forum: Determining Molecular Shape (VSEPR)
Topic: AX2E2
Replies: 14
Views: 162

Re: AX2E2

Yes this is a bent shape with bond angles less than 109.5
by Ricardo Martin 1J
Thu Dec 06, 2018 10:24 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Trigonal Bipyramidal
Replies: 6
Views: 86

Re: Trigonal Bipyramidal

Ethan Breaux 1J wrote:Maybe I'm just reading this wrong but are you referring to see saw?

I don't think it's see saw, I think it is T-shape because I believe the structure being described has 3 bonds and 2 lone pairs, but maybe I also read it wrong.
by Ricardo Martin 1J
Thu Dec 06, 2018 10:19 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 3
Replies: 38
Views: 511

Re: Test 3

A trick I found helpful is memorizing the VSEPR equations such as AX3E2 and knowing what shape corresponds to those equations because as soon as you drew the Lewis Structure you could conclude the VSEPR equation and therefore concluding the shape. This also helps with knowing the hybridization.
by Ricardo Martin 1J
Fri Nov 09, 2018 3:10 pm
Forum: Bond Lengths & Energies
Topic: Bond Lengths
Replies: 6
Views: 61

Re: Bond Lengths

I don't think you have to memorize specific bond lengths but should probably know that a single bond is longer the a double bond which is longer than a triple bond.
by Ricardo Martin 1J
Fri Nov 09, 2018 3:06 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge of Oxygen
Replies: 6
Views: 86

Re: Formal Charge of Oxygen

Oxygen is more electronegative than carbon which attracts the electrons to them usually giving it a negative charge.
by Ricardo Martin 1J
Fri Nov 09, 2018 3:04 pm
Forum: Dipole Moments
Topic: Polarizability
Replies: 5
Views: 59

Re: Polarizability

The polarizability of a molecule depends the size of the molecule and the number of electrons that the molecule has.
by Ricardo Martin 1J
Thu Nov 01, 2018 9:11 pm
Forum: Resonance Structures
Topic: Most Stable Configuration
Replies: 11
Views: 114

Re: Most Stable Configuration

The most stable configuration for a resonance structure would be one where the formal charge is closest to 0, which could be find with the equation FC= V (valence electrons) - (L (lone pair electrons) + s/2 (shared electrons divided by 2).
by Ricardo Martin 1J
Thu Nov 01, 2018 9:06 pm
Forum: Electronegativity
Topic: Test 3. Question 7.
Replies: 6
Views: 198

Re: Test 3. Question 7.

Difference in electronegativity defines ionic character.
by Ricardo Martin 1J
Thu Nov 01, 2018 9:03 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic vs Covalent Bonds
Replies: 18
Views: 217

Ionic vs Covalent Bonds

What is the difference between ionic and covalent bonds?
by Ricardo Martin 1J
Tue Oct 23, 2018 10:13 pm
Forum: *Shrodinger Equation
Topic: Test 2
Replies: 5
Views: 220

Re: Test 2

Test 2 covers everything from lecture #4 to lecture #10 (October 5 to October 19) which is the quantum world to multi-electron atoms.
by Ricardo Martin 1J
Tue Oct 23, 2018 10:04 pm
Forum: Quantum Numbers and The H-Atom
Topic: m with subscript l
Replies: 4
Views: 59

m with subscript l

what does m with subscript l tell you about the atom?
by Ricardo Martin 1J
Tue Oct 23, 2018 9:54 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Px. Py, Pz
Replies: 6
Views: 115

Re: Px. Py, Pz

I understand that Px Py Pz tell you something about the orientation of the orbital, however, what about the orientation does it tell you about, most specifically what does Pz tell you?
by Ricardo Martin 1J
Wed Oct 17, 2018 9:37 pm
Forum: Properties of Electrons
Topic: 7th edition 1A.11
Replies: 3
Views: 44

Re: 7th edition 1A.11

I say just do it just in case and it is pretty well-explained in the book if you do take a look.
by Ricardo Martin 1J
Wed Oct 17, 2018 9:32 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: > vs =
Replies: 1
Views: 31

> vs =

Why does the Heisenberg Indeterminacy equation have a greater than or equal to sign instead of an equal sign? Will this always be the case?
by Ricardo Martin 1J
Wed Oct 17, 2018 9:15 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Plane
Replies: 2
Views: 26

Nodal Plane

Can someone explain to me what a nodal plane is and its function?
by Ricardo Martin 1J
Sat Oct 13, 2018 2:21 pm
Forum: DeBroglie Equation
Topic: Angstrom?
Replies: 8
Views: 132

Re: Angstrom?

An angstrom is equivalent to 1x10^-10 m and Dr. Lavelle stated that it would be common to find wavelengths to the ^-10m, therefore, the angstrom is used for convenience in writing these lengths.
by Ricardo Martin 1J
Sat Oct 13, 2018 2:14 pm
Forum: Einstein Equation
Topic: Units for v(frequency)
Replies: 11
Views: 109

Re: Units for v(frequency)

Hz and s^-1 are interchangeable because they are equivalent. I see Hz used more often than s^-1, but I doubt that you will be marked wrong for using one or the other.
by Ricardo Martin 1J
Sat Oct 13, 2018 2:11 pm
Forum: DeBroglie Equation
Topic: Equations
Replies: 9
Views: 74

Re: Equations

I believe we will be given all the equations and constants for every test/exam we take, but I believe you should still memorize the formulas because I find that it helps me to know exactly what to use when reading a problem. However, the formulas given on the test could be good for double checking t...
by Ricardo Martin 1J
Thu Oct 04, 2018 3:35 pm
Forum: Significant Figures
Topic: SIG FIGS in ratios
Replies: 4
Views: 76

SIG FIGS in ratios

When a problem asks for a ratio would we also need to make sure all values of the ratio are in terms of significant figures? For example in exercise F.9 (of the 7th edition), the ratio of the answer would be 1O:2.67C:2.67H, however, the lowest number of significant figures from the problem is three ...
by Ricardo Martin 1J
Thu Oct 04, 2018 3:09 pm
Forum: SI Units, Unit Conversions
Topic: SI Units
Replies: 10
Views: 166

Re: SI Units

Do all our final answers need to be converted to the base SI unit (ex:meter, kilogram, mole) or do we just use the closest prefix to it? And if we leave our answer in the base SI unit and do not use a prefix simplifying the value would our answer be wrong even if both answers would be mathematically...
by Ricardo Martin 1J
Thu Oct 04, 2018 2:51 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical Formula
Replies: 6
Views: 67

Re: Empirical Formula

You do not need to do it every time, you can use any amount you want for mass to solve for how much the percentage accounts for, however, since percent means a part of ONE HUNDRED, then it is much easier to use 100g as the mass because you would only need to change the percent sign to grams.

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