Search found 80 matches

by rohun2H
Sun Feb 16, 2020 8:39 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneous
Replies: 13
Views: 19

Re: Spontaneous

If delta G is negative, the reaction is considered spontaneous (favorable).
by rohun2H
Sun Feb 16, 2020 8:37 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equilibrium
Replies: 15
Views: 50

Re: Equilibrium

Neither reaction is favored at equilibrium.
by rohun2H
Sun Feb 16, 2020 8:35 pm
Forum: Van't Hoff Equation
Topic: Enthalpy, Entropy, and Gibbs Free Energy
Replies: 7
Views: 33

Re: Enthalpy, Entropy, and Gibbs Free Energy

Change in temperature.
by rohun2H
Sun Feb 16, 2020 8:34 pm
Forum: Van't Hoff Equation
Topic: Van Hoff's Constants
Replies: 6
Views: 18

Re: Van Hoff's Constants

I believe you assume standard conditions.
by rohun2H
Sun Feb 16, 2020 8:33 pm
Forum: Van't Hoff Equation
Topic: delta s
Replies: 9
Views: 29

Re: delta s

Delta s does not change, both s values may change but the difference between final and intitial remains constant.
by rohun2H
Mon Feb 10, 2020 10:21 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Exothermic reactions
Replies: 5
Views: 19

Re: Exothermic reactions

Lavelle briefly mentioned determining spontaneity at the beginning of thermo but I believe he'll be explaining this concept sometime this week.
by rohun2H
Mon Feb 10, 2020 10:17 am
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: Positional/Residual Entropy
Replies: 3
Views: 13

Re: Positional/Residual Entropy

A molecule at 0 K will have 0 residual entropy, but only if it is perfectly ordered will the molecule have 0 entropy, if it is not perfectly ordered then some entropy will still be present.
by rohun2H
Mon Feb 10, 2020 10:13 am
Forum: Calculating Work of Expansion
Topic: Midterm equation sheet
Replies: 16
Views: 94

Re: Midterm equation sheet

Yes, it is the same sheet.
by rohun2H
Mon Feb 10, 2020 10:12 am
Forum: Calculating Work of Expansion
Topic: Constant Volume and Pressure Values
Replies: 8
Views: 31

Re: Constant Volume and Pressure Values

The monoatomic values are on the constants and equations sheet.
by rohun2H
Mon Feb 10, 2020 10:10 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Extensive and State properties
Replies: 3
Views: 12

Re: Extensive and State properties

They are separate concepts I believe.
by rohun2H
Mon Feb 03, 2020 12:41 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Constant Volume and Pressure
Replies: 7
Views: 23

Re: Constant Volume and Pressure

Constant volume and pressure indicates that they do not change during the reaction.
by rohun2H
Mon Feb 03, 2020 12:39 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Constant pressure
Replies: 19
Views: 70

Re: Constant pressure

Yes, constant external pressure.
by rohun2H
Mon Feb 03, 2020 12:37 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Types of Systems
Replies: 7
Views: 25

Re: Types of Systems

A closed system can exchange heat but not matter
by rohun2H
Mon Feb 03, 2020 12:30 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: kinetics
Replies: 8
Views: 25

Re: kinetics

Kinetics is more interested in rate, whereas thermodynamics considers more only final and initial.
by rohun2H
Mon Feb 03, 2020 12:28 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: enthalpy
Replies: 7
Views: 19

Re: enthalpy

Enthalpy is the total heat of a system.
by rohun2H
Sun Jan 26, 2020 9:17 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 4
Views: 17

Re: Hess's Law

Just the first I believe.
by rohun2H
Sun Jan 26, 2020 9:16 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Exothermic and Endothermic
Replies: 11
Views: 33

Re: Exothermic and Endothermic

Delta H is the enthalpy of products minus the enthalpy of reactants.
by rohun2H
Sun Jan 26, 2020 9:11 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Meaning of State Function
Replies: 8
Views: 22

Re: Meaning of State Function

State function means it is independent of path taken. Work is an example of NOT a state function, it is dependent on path taken.
by rohun2H
Sun Jan 26, 2020 9:04 pm
Forum: Phase Changes & Related Calculations
Topic: Why does steam cause burns?
Replies: 29
Views: 108

Re: Why does steam cause burns?

The diagram Lavelle showed in class was the temperature curve of water.
by rohun2H
Sun Jan 26, 2020 8:56 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Changes
Replies: 7
Views: 30

Re: Phase Changes

Add the enthalpy of the phase change.
by rohun2H
Wed Jan 15, 2020 2:52 pm
Forum: Phase Changes & Related Calculations
Topic: Autoprotolysis
Replies: 15
Views: 82

Re: Autoprotolysis

Autoprotolysis is proton transfer between the same type of molecule.
by rohun2H
Wed Jan 15, 2020 2:49 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction shifts right or left?
Replies: 14
Views: 61

Re: Reaction shifts right or left?

Yes, a shift to the left favors the reverse reaction so more reactants will be made. A shift to the right favors the forward reaction so more products will be made.
by rohun2H
Wed Jan 15, 2020 2:39 pm
Forum: Ideal Gases
Topic: bars vs atm
Replies: 8
Views: 34

Re: bars vs atm

Mainly ensure consistency with units.
by rohun2H
Wed Jan 15, 2020 2:34 pm
Forum: Ideal Gases
Topic: equilibrium constant
Replies: 5
Views: 28

Re: equilibrium constant

Most simply, K= Products/Reactants
by rohun2H
Fri Jan 10, 2020 9:58 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Do solids and liquids count in Q?
Replies: 5
Views: 26

Re: Do solids and liquids count in Q?

Q is calculated in the same manner as K, so no.
by rohun2H
Fri Jan 10, 2020 9:56 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: liquids and aqueous solutions
Replies: 4
Views: 17

Re: liquids and aqueous solutions

K is dependent on concentration.
by rohun2H
Fri Jan 10, 2020 9:53 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Comparing K and Q
Replies: 6
Views: 33

Re: Comparing K and Q

Q can give us an indication of the reaction in that it can identify whether the forward or reverse reaction is favored in order to reach equilibrium at a given moment.
by rohun2H
Fri Jan 10, 2020 9:50 am
Forum: Ideal Gases
Topic: 5G1 true/false
Replies: 8
Views: 55

Re: 5G1 true/false

Q would be larger but ultimately the reaction would reach equilibrium and K remains the same.
by rohun2H
Fri Jan 10, 2020 9:46 am
Forum: Ideal Gases
Topic: Reaction Quotient (Q)
Replies: 8
Views: 30

Re: Reaction Quotient (Q)

Q is calculated in the same manner as K and used as a comparison to identify if given concentrations of a reaction are at equilibrium.
by rohun2H
Sat Dec 07, 2019 10:24 pm
Forum: Biological Examples
Topic: Chemotherapy drugs
Replies: 7
Views: 60

Re: Chemotherapy drugs

Transplatin may also be useful to know.
by rohun2H
Sat Dec 07, 2019 10:19 pm
Forum: Polyprotic Acids & Bases
Topic: polyprotic acids
Replies: 3
Views: 37

Re: polyprotic acids

The negative charge created after the first dissociation makes it more difficult for the second dissociation to occur.
by rohun2H
Sat Dec 07, 2019 10:17 pm
Forum: Calculating the pH of Salt Solutions
Topic: Sig Figs for logarithmic funcitons
Replies: 6
Views: 60

Re: Sig Figs for logarithmic funcitons

I believe sig figs are also counted after the decimal when provided a pH and you are asked to give some numerical number, say a concentration for example. It was briefly mentioned by my TA.
by rohun2H
Sat Dec 07, 2019 10:13 pm
Forum: Polyprotic Acids & Bases
Topic: How can you tell
Replies: 11
Views: 101

Re: How can you tell

Typically, there will be more than one hydrogen.
by rohun2H
Sat Dec 07, 2019 10:07 pm
Forum: Air Pollution & Acid Rain
Topic: dirty/clean coal
Replies: 6
Views: 59

Re: dirty/clean coal

I think the main takeaway is that dirty coal has sulfur in it.
by rohun2H
Tue Nov 26, 2019 9:54 am
Forum: Amphoteric Compounds
Topic: Oxides
Replies: 4
Views: 31

Re: Oxides

It is most useful to know the patterns of the periodic table.
by rohun2H
Tue Nov 26, 2019 9:50 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Why are inorganic acids stronger?
Replies: 8
Views: 57

Re: Why are inorganic acids stronger?

Stronger acids are characterized by their ability to lose hydrogen ions more easily. It is in this way that strong acids can reach 100% ionization when dissociating in water.
by rohun2H
Tue Nov 26, 2019 9:38 am
Forum: Bronsted Acids & Bases
Topic: Equlibrium Constant Expression for Strong Acids/Bases
Replies: 3
Views: 15

Re: Equlibrium Constant Expression for Strong Acids/Bases

Strong acids/bases are assumed, when approximating, to reach 100% ionization. Therefore, the denominator of the equilibrium constant equation is essentially zero which is why we do not use the equilibrium constant for strong acids/bases.
by rohun2H
Tue Nov 26, 2019 9:35 am
Forum: Lewis Acids & Bases
Topic: When is an acid considered Bronsted?
Replies: 9
Views: 60

Re: When is an acid considered Bronsted?

There simply exist two common ways of defining an acid (or a base). Both the Bronsted definition and Lewis definition refer to the same thing yet identify it in different ways.
by rohun2H
Sun Nov 24, 2019 6:37 pm
Forum: Hybridization
Topic: Strength of sigma vs pi bonds
Replies: 6
Views: 29

Re: Strength of sigma vs pi bonds

Sigma bonds are stronger due to greater overlap end-to-end but also be sure to remember sigma bonds allow for rotation whereas pi bonds are rigid.
by rohun2H
Sun Nov 24, 2019 6:32 pm
Forum: Naming
Topic: Prefixes
Replies: 5
Views: 31

Re: Prefixes

If the ligand already has a name with di-, tri-, tetra-, or polydentate.
by rohun2H
Sun Nov 24, 2019 6:29 pm
Forum: Naming
Topic: Week 9 and Week 10 HW?
Replies: 21
Views: 136

Re: Week 9 and Week 10 HW?

Should be fine as long as you let your TA know.
by rohun2H
Sun Nov 24, 2019 6:20 pm
Forum: Naming
Topic: Coordination number
Replies: 7
Views: 33

Re: Coordination number

The coordination number is determined by the bonds to the central atom.
by rohun2H
Sun Nov 24, 2019 5:46 pm
Forum: Hybridization
Topic: How does hybridization happen?
Replies: 3
Views: 19

Re: How does hybridization happen?

Hybridization is the mixture of valence atomic orbitals during bond formation to explain the observed structure.
by rohun2H
Sun Nov 17, 2019 8:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 2
Replies: 19
Views: 131

Re: Test 2

Technically, the shape does not matter in a lewis structure, although Lavelle said drawing them symmetrically (or now similar to VSEPR model) would help to visualize the molecule.
by rohun2H
Sun Nov 17, 2019 8:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angle
Replies: 3
Views: 20

Re: Bond angle

I believe that we will have to know slightly less/more and be able to make comparisons between two bond angles (ex. which is less?).
by rohun2H
Sun Nov 17, 2019 8:18 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: This Week Test
Replies: 12
Views: 70

Re: This Week Test

Nick Lewis 3D wrote:Have we gone over sigma and pi bonds yet? Do we have any more information about what exact material will be tested?

Lavelle said he would discuss sigma and pi bonds on Monday.
by rohun2H
Sun Nov 17, 2019 8:16 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Dipole
Replies: 3
Views: 20

Re: Dipole

Dipoles cancel in the same way which vectors cancel. A vector can be broken down into a component in each direction. When summed, vectors that equal 0 are dipoles that cancel.
by rohun2H
Sun Nov 17, 2019 8:09 pm
Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
Topic: Rod vs spherical shaped molecules
Replies: 8
Views: 59

Re: Rod vs spherical shaped molecules

Rod-shaped molecules allow for instantaneous dipoles to be closer and thereby stronger because rod-shaped molecules can align with more surface area close to other nearby rod-shaped molecules.
by rohun2H
Mon Nov 11, 2019 1:42 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Boiling and Melting Points
Replies: 7
Views: 36

Re: Boiling and Melting Points

As intermolecular forces increase, the structure becomes more stable and therefore the melting/boiling points will also increase.
by rohun2H
Mon Nov 11, 2019 1:39 am
Forum: Bond Lengths & Energies
Topic: Size
Replies: 9
Views: 45

Re: Size

As atomic radius increases, bond length also increases.
by rohun2H
Mon Nov 11, 2019 1:36 am
Forum: Electronegativity
Topic: dipole moments
Replies: 7
Views: 27

Re: dipole moments

Yes a greater difference in electronegativity typically results in a greater bond dipole moment.
by rohun2H
Mon Nov 11, 2019 1:30 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polar vs covalent
Replies: 7
Views: 33

Re: Polar vs covalent

You can use general trends of electronegativity in the periodic table.
by rohun2H
Mon Nov 11, 2019 1:29 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Anions
Replies: 7
Views: 31

Re: Anions

Anions are polarizable (exhibiting distortion) whereas cations have polarizing power (distorting anions).
by rohun2H
Sun Nov 03, 2019 11:14 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: polarizing power
Replies: 2
Views: 27

Re: polarizing power

Ions which cause large distortions.
by rohun2H
Sun Nov 03, 2019 10:59 am
Forum: Dipole Moments
Topic: Midterm
Replies: 8
Views: 92

Re: Midterm

I believe he said up to Friday's lecture, excluding the last powerpoint slide.
by rohun2H
Sun Nov 03, 2019 10:44 am
Forum: Electronegativity
Topic: electronegativity trend
Replies: 9
Views: 38

Re: electronegativity trend

Electrons will be further away from the nucleus in increasing shells, therefore pull on electrons is less.
by rohun2H
Sun Nov 03, 2019 10:38 am
Forum: Resonance Structures
Topic: Resonance Stability
Replies: 3
Views: 18

Re: Resonance Stability

A molecule with resonance has more stability as the multiple bonds can exist in various positions throughout the molecule.
by rohun2H
Sun Nov 03, 2019 10:25 am
Forum: Octet Exceptions
Topic: Expanded Octets and Formal Charge
Replies: 3
Views: 24

Re: Expanded Octets and Formal Charge

The expanded octet rule applies for atoms on the periodic table row 3 and beyond because electrons can utilize the d subshell.
by rohun2H
Sun Oct 27, 2019 5:50 pm
Forum: Lewis Structures
Topic: Lone pair
Replies: 8
Views: 38

Re: Lone pair

A lone pair is a pair of electrons not shared with another atom.
by rohun2H
Sun Oct 27, 2019 5:48 pm
Forum: Ionic & Covalent Bonds
Topic: Resonance
Replies: 10
Views: 72

Re: Resonance

Resonance indicates that you can put double bonds in different positions when drawing lewis structures.
by rohun2H
Sun Oct 27, 2019 5:42 pm
Forum: Trends in The Periodic Table
Topic: Ionization energy
Replies: 12
Views: 99

Re: Ionization energy

Ionization energy is also important when drawing lewis structures as the atom with the lowest ionization energy is typically drawn as the central atom.
by rohun2H
Sun Oct 27, 2019 5:39 pm
Forum: Trends in The Periodic Table
Topic: Central Atom
Replies: 13
Views: 59

Re: Central Atom

Typically you choose the atom with the lowest ionization energy as the central atom.
by rohun2H
Sun Oct 27, 2019 5:30 pm
Forum: Trends in The Periodic Table
Topic: Electron affinity.
Replies: 8
Views: 28

Re: Electron affinity.

Electron affinity is essentially the amount of energy spent when an electron is added to a neutral atom, forming an anion.
by rohun2H
Sat Oct 19, 2019 7:25 pm
Forum: Quantum Numbers and The H-Atom
Topic: Correlation Between n and l
Replies: 6
Views: 55

Re: Correlation Between n and l

l is the angular momentum quantum number or "shape."
by rohun2H
Sat Oct 19, 2019 7:21 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg
Replies: 4
Views: 15

Re: Heisenberg

It is a measure of uncertainty since it cannot be exactly determined the momentum and position of a particle simultaneously.
by rohun2H
Sat Oct 19, 2019 7:15 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbitals in relation to arrows
Replies: 10
Views: 95

Re: Orbitals in relation to arrows

Hund's rule asserts that due to electron repulsion, electrons in the same subshell occupy different orbitals with parallel spin. Parallel spin indicates that electrons have the same spin whereas 2 electrons with opposite spin are paired.
by rohun2H
Sat Oct 19, 2019 7:07 pm
Forum: *Shrodinger Equation
Topic: Schrodinger Equation
Replies: 4
Views: 37

Re: Schrodinger Equation

It allows us to calculate an electron's wave function.
by rohun2H
Sat Oct 19, 2019 7:06 pm
Forum: Photoelectric Effect
Topic: Work Funtion
Replies: 2
Views: 31

Work Funtion

What is the difference between the work function and threshold energy?
by rohun2H
Sat Oct 12, 2019 4:20 pm
Forum: Properties of Electrons
Topic: Speed of an Electron
Replies: 3
Views: 42

Re: Speed of an Electron

Typically, less than the speed of light.
by rohun2H
Sat Oct 12, 2019 3:42 pm
Forum: Photoelectric Effect
Topic: Energy in Photoelectric Effect
Replies: 5
Views: 29

Re: Energy in Photoelectric Effect

If threshold energy is surpassed, electrons will be emitted. Given the amount of energy is greater than threshold, the number of electrons emitted is dependent on intensity.
by rohun2H
Sat Oct 12, 2019 3:27 pm
Forum: DeBroglie Equation
Topic: De Broglie's Equation
Replies: 13
Views: 78

Re: De Broglie's Equation

Any moving particle with momentum, cannot be applied to light.
by rohun2H
Sat Oct 12, 2019 3:20 pm
Forum: Properties of Light
Topic: Frequency vs. Wavelength
Replies: 15
Views: 106

Re: Frequency vs. Wavelength

Frequency and wavelength are inversely proportional, this can be seen using the formula c = λv.
by rohun2H
Sat Oct 12, 2019 3:12 pm
Forum: Properties of Light
Topic: Diffraction and Water
Replies: 4
Views: 36

Re: Diffraction and Water

I believe he was just trying to give a visual example. When you drop two rocks in the water next to each other, it is easy to see how the waves (ripples in the water) interact with each other and form both constructive and destructive interference.
by rohun2H
Sun Oct 06, 2019 4:35 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: avogadro's number
Replies: 4
Views: 44

Re: avogadro's number

Typically when converting between molecules and moles.

1 mole = 6.022 * 10^23 molecules
by rohun2H
Sun Oct 06, 2019 4:32 pm
Forum: SI Units, Unit Conversions
Topic: Unit Conversions
Replies: 11
Views: 126

Re: Unit Conversions

Divide by Avogadro's number.

1 mole = 6.022 * 10^23 atoms (molecules)
by rohun2H
Sun Oct 06, 2019 4:21 pm
Forum: Limiting Reactant Calculations
Topic: Order of atoms in molecules
Replies: 6
Views: 60

Re: Order of atoms in molecules

My TA said that it may be ordered in any way and will still be an acceptable answer, at least for now.
by rohun2H
Sun Oct 06, 2019 4:09 pm
Forum: Empirical & Molecular Formulas
Topic: What decimal place to round to when taking masses from the Periodic Table?
Replies: 19
Views: 197

Re: What decimal place to round to when taking masses from the Periodic Table?

I think it is best to use the entire figure given, then round the final answer based on sig figs.
by rohun2H
Sun Oct 06, 2019 3:51 pm
Forum: Properties of Light
Topic: m/s^-1
Replies: 4
Views: 34

Re: m/s^-1

(m.s^-1) is a different way of expressing (m/s); the meaning is the same.

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