## Search found 57 matches

Sat Mar 09, 2019 9:24 pm
Forum: Second Order Reactions
Topic: Determining the Order of a Reaction
Replies: 3
Views: 179

### Re: Determining the Order of a Reaction

Most of the time, you will have to find the order of the reaction by testing the different graphs given in lecture and seeing which one is linear.
Sat Mar 09, 2019 9:16 pm
Forum: General Rate Laws
Topic: integrals
Replies: 8
Views: 351

### Re: integrals

If you look at the class website, you can find videos and links that will help with the math/calculus portion of this topic.
Sat Mar 09, 2019 9:07 pm
Forum: General Rate Laws
Topic: Rate Law Dependence
Replies: 1
Views: 85

### Re: Rate Law Dependence

Whether or not the rate law depends on the concentration of reactants depends on the order to the reaction.
Sun Mar 03, 2019 1:28 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: pH at 10 C
Replies: 3
Views: 158

### Re: pH at 10 C

Yes, for my version, increasing the temperature led to a basic solution.
Sun Mar 03, 2019 1:26 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2
Replies: 7
Views: 393

### Re: Test 2

Yes, correct. The more positive the E value, the stronger the oxidizing power.
Sun Mar 03, 2019 1:23 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: TEST 2
Replies: 3
Views: 182

### Re: TEST 2

For the pH question, I think you had to use the Van't Hoff equation, which was given on the equation sheet. This equation relates the change in the equilibrium constant with the change in temperature. Using this equation, you can find the new equilibrium constant as a result of the change in tempera...
Fri Feb 22, 2019 9:51 pm
Forum: Balancing Redox Reactions
Topic: Redox Rxn
Replies: 3
Views: 178

### Re: Redox Rxn

In my opinion, just know the common ones, such as group 1 metals and group 2 metals, which are +1 and +2, respectively. Also, know that oxygen is generally -2 and chlorine is generally -1. Not sure if we will need to memorize the others.
Fri Feb 22, 2019 9:26 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity
Replies: 2
Views: 110

### Re: Spontaneity

A reaction is considered spontaneous if the Gibbs free energy is negative. Knowing only the change in enthalpy or entropy cannot determine spontaneity.
Fri Feb 22, 2019 9:24 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt bridge
Replies: 3
Views: 149

### Re: Salt bridge

A salt bridge maintains the electrical neutrality of a battery. Negative ions would flow into the left compartment while positive ions would flow into the right compartment.
Tue Feb 19, 2019 11:36 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: Third Law concept and problem types
Replies: 4
Views: 365

### Re: Third Law concept and problem types

Yes, essentially the third law of thermodynamics is saying that at 0 degrees K, there is no vibrational, rotational, or translational entropy. The only possible entropy results from positional and residual. Thus, knowing the Boltzmann equation would come in handy when asked a question about the resi...
Tue Feb 19, 2019 11:33 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: System vs Surroundings
Replies: 14
Views: 653

### Re: System vs Surroundings

Yes, the system vs. surrounding should not be something you have to memorize. As mentioned before, the system is simply the situation in question, such as a piston. Since the first law of thermodynamics states the conservation of energy, a change in energy of the system means a resultant change in s...
Tue Feb 19, 2019 11:29 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: TEST 3
Replies: 7
Views: 578

### Re: TEST 3

I believe you mean for Test 2?
Sun Feb 10, 2019 9:31 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Entropy and Enthalpy
Replies: 3
Views: 190

### Re: Entropy and Enthalpy

Enthalpy has the letter "h" in it, so it corresponds to H. Not sure if that helps much, but usually, you should be able to differentiate between entropy and enthalpy based on what the problem is asking.
Sun Feb 10, 2019 9:28 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Midterm 2019
Replies: 9
Views: 314

### Re: Midterm 2019

Since he said up to entropy, it is up to the "Second and Third Laws of Thermodynamics", but only part of Chapter 9.
Sun Feb 10, 2019 9:27 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Midterm
Replies: 2
Views: 155

### Re: Midterm

Yes, you can check "Important Midterm Information" on his website.
Sun Feb 03, 2019 6:32 pm
Forum: Phase Changes & Related Calculations
Topic: Work by expansion
Replies: 3
Views: 139

### Re: Work by expansion

Yes, use the conversion ratio which should be given to us, either in the problem or on the formula sheet to convert.
Sun Feb 03, 2019 6:30 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: PV=nRT
Replies: 5
Views: 303

### Re: PV=nRT

This equation describes an ideal gas, which is essentially a simplified model of real gases to help us in calculations. Since there are 4 unknown's in this equation, we can use this equation when we have three givens, which then can be used to calculate the final unknown.
Sun Feb 03, 2019 6:28 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: HW
Replies: 3
Views: 141

### Re: HW

Yes, we should still be able to do thermochemistry problems for HW.
Tue Jan 29, 2019 5:51 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: standard enthalpies of formation
Replies: 2
Views: 105

### Re: standard enthalpies of formation

The standard enthalpy of formation is the net change in enthalpy, or in simpler terms, the net change in heat, for one mole of a substance in standard state to be formed from its pure elements. A standard enthalpy of formation of 0 means that the substance is already in standard state.
Tue Jan 29, 2019 5:45 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: delta u eqn
Replies: 3
Views: 165

### Re: delta u eqn

Essentially, the change in internal energy of a system, deltaU, equals the net heat transfer into the system, Q, plus the net work, W, done on the system. This is the first law of thermodynamics.
Mon Jan 28, 2019 10:34 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4E.5
Replies: 1
Views: 94

### Re: 4E.5

Carbon and Hydrogen cannot have a triple bond because a hydrogen atom only has one valence electron.
Sat Jan 19, 2019 3:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K - small verses big
Replies: 4
Views: 185

### Re: K - small verses big

A small Ka essentially means a large Kb, since they are inversely proportional. The larger the acid or base equilibrium constant, the stronger the acid or base.
Sat Jan 19, 2019 3:32 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Protonation
Replies: 1
Views: 108

### Re: Protonation

Protonation and Deprotonation is simply the acceptance/donation of a proton as a result of a reaction. For weak acids/bases, since it is not complete disassociation, there is a percentage that remains an acid/base as a result of equilibrium. Percent protonation is the change in concentration for the...
Sat Jan 19, 2019 3:28 pm
Forum: Student Social/Study Group
Topic: ICE Table
Replies: 6
Views: 164

### Re: ICE Table

Usually, if the problem gives you initial concentrations of the reactants and asks for the equilibrium concentrations of each molecule, you can most likely use an ICE table to solve the problem.
Sun Jan 13, 2019 1:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constant Eq.
Replies: 4
Views: 170

### Re: Equilibrium Constant Eq.

No, you do not need to include solids and liquids when calculating the equilibrium constant.
Sun Jan 13, 2019 1:02 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equations
Replies: 6
Views: 242

### Re: Equations

Yes, you could easily convert between partial pressure to concentration by using PV=nRT.
Sun Jan 13, 2019 12:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: "bar" meaning
Replies: 4
Views: 164

### Re: "bar" meaning

Yes, it is also equivalent to 100 kPa, if that helps.
Fri Dec 07, 2018 8:50 pm
Forum: Hybridization
Topic: Hybridization on Test
Replies: 3
Views: 304

### Re: Hybridization on Test

Yes. For instance, oxygen is often displayed without its lone pairs, so we must account for them when determining hybridization.
Fri Dec 07, 2018 8:49 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: Review questions
Replies: 3
Views: 458

### Re: Review questions

Although S has a higher electronegativity leading to stronger dipole-dipole interactions, Se has a larger atomic mass, resulting in stronger London dispersion forces which are more stronger than the dipole-dipole interactions. Thus, H2Se has a higher boiling point.
Fri Dec 07, 2018 8:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AX2E3 (i.e. linear) Molecular geometry
Replies: 1
Views: 376

### Re: AX2E3 (i.e. linear) Molecular geometry

The electron density shape would be based off the trigonal bipyramidal shape. The three lone pairs will take the three equatorial positions, leaving the two axial positions for the atoms. This would result in a symmetrical linear molecular shape.
Sun Dec 02, 2018 3:01 pm
Forum: Bronsted Acids & Bases
Topic: Electronegativity
Replies: 2
Views: 135

### Re: Electronegativity

Higher electronegativity allows for easier dissociation. A strong acid completely dissociates in water, so the higher the electronegativity, the stronger the acid.
Sun Dec 02, 2018 1:39 pm
Forum: Bronsted Acids & Bases
Topic: Proton "Donation"
Replies: 4
Views: 213

### Re: Proton "Donation"

Yes, a Bronsted acid donates a hydrogen ion (H+).
Thu Nov 29, 2018 2:45 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.95 6th ed
Replies: 3
Views: 191

### Re: 4.95 6th ed

I believe it is asking for the lewis structure with the greatest contribution to the resonance, so essentially the most stable structure.
Sun Nov 25, 2018 2:02 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Hypervalent Compounds
Replies: 1
Views: 106

### Re: Hypervalent Compounds

To my knowledge, not all compounds containing period 3 or below elements are hypervalent compounds as the expanded octet is not always necessary.
Sun Nov 25, 2018 1:51 pm
Forum: Hybridization
Topic: Equatorial lone pair
Replies: 2
Views: 106

### Re: Equatorial lone pair

Essentially, an equatorial lone pair is generally the lowest energy because it is only strongly interacting with the two axial electron pairs, whereas axial lone pair strongly interacts the three equatorial electron pairs.
Sun Nov 25, 2018 1:49 pm
Forum: Lewis Structures
Topic: Central atom of CNO-
Replies: 2
Views: 86

### Re: Central atom of CNO-

Nitrogen would be the central atom in this case. If the chemical formula was given as OCN-, then carbon would be the central atom.
Sun Nov 18, 2018 6:12 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Geometry
Replies: 6
Views: 278

### Re: Molecular Geometry

For instance, the electron density geometry for H2O is tetrahedral, since there are 2 bonded pairs and 2 lone pairs. The molecular geometry of H2O is bent, since only 2 atoms are bonded with the central atom.
Sun Nov 18, 2018 5:19 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge of Central Atom
Replies: 4
Views: 464

### Re: Formal Charge of Central Atom

I'm not exactly sure about ClO2+, but generally, you would want the formal charge for the central atom to be 0, and the outer atoms with the charge.
Sun Nov 18, 2018 2:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs
Replies: 8
Views: 489

### Re: Lone Pairs

Lone pairs are considered as an electron density when regarding shape of a molecule. It has a larger repulsion when compared to bonded pairs of electrons.
Sat Nov 10, 2018 3:55 pm
Forum: Dipole Moments
Topic: Dipole-Induced Dipole
Replies: 3
Views: 134

### Re: Dipole-Induced Dipole

Water is a dipole as the oxygen is electronegative, causing O to be more negative than the H's. If a water molecule (dipole) was nearby a N2 molecule (nonpolar), the N closest to the O would have a slightly positive charge, causing the other N to have a slightly negative charge, creating a dipole. T...
Sat Nov 10, 2018 3:50 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability
Replies: 4
Views: 238

### Re: Polarizability

Essentially, the larger the atom (the more electrons), the easier it is for electrons to become distorted, since the pull on the outer electrons is less for larger atoms.
Sat Nov 10, 2018 3:10 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen bonding
Replies: 7
Views: 384

### Re: Hydrogen bonding

The electronegativity of oxygen causes water to be polar, leading to hydrogen bonding. Because of hydrogen bonding, H2O requires more energy needed to break the bonds, thus it has a much higher boiling point/melting point than that of H2S.
Sat Nov 03, 2018 4:49 pm
Forum: Octet Exceptions
Topic: Adding a Double bond or leaving a lone pair [ENDORSED]
Replies: 3
Views: 195

### Re: Adding a Double bond or leaving a lone pair[ENDORSED]

You would have to find the formal charges of each atom in each structure. You would want to find the structure with the least formal charge (lowest energy).
Sat Nov 03, 2018 4:47 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 6th Edition 2.53
Replies: 1
Views: 220

### Re: 6th Edition 2.53

Hund's rule states that every subshell must be singlely occupied by one electron before it can be doubly occupied. For instance, you know the electron config of Ga, which is [Ar]3d10 4s2 4p1. There is one unpaired electron in this case, because there is one electron in the 4p orbital. For Se, the el...
Sat Nov 03, 2018 4:42 pm
Forum: Student Social/Study Group
Topic: Sig Figs on Midterm
Replies: 13
Views: 871

### Re: Sig Figs on Midterm

I think just to be safe, you should follow the sigfig guidelines.
Sat Oct 27, 2018 4:09 pm
Forum: Lewis Structures
Topic: Order in Drawing Lewis Structures
Replies: 2
Views: 54

### Re: Order in Drawing Lewis Structures

To my knowledge, it does not matter which side you put the dots, as long as you follow Hund's rule where electrons fill the available subshells before pairing up to have the lowest energy state.
Sat Oct 27, 2018 3:55 pm
Forum: DeBroglie Equation
Topic: Homework Question 1B.15
Replies: 3
Views: 127

### Re: Homework Question 1B.15

Yes, definitely use meters per second. And in this case, using the KE = (1/2)mv^2 then using the E = (planck's constant)(frequency) would be easiest to solve this problem.
Sat Oct 27, 2018 3:50 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg- In relation to wavelength
Replies: 7
Views: 351

### Re: Heisenberg- In relation to wavelength

The uncertainty in momentum is inversely proportional to the uncertainty in wavelength, meaning a larger uncertainty in momentum will lead to a smaller uncertainty in wavelength, and vice versa.
Sat Oct 20, 2018 9:26 pm
Forum: Properties of Light
Topic: Atomic Spectra pre-module quiz
Replies: 1
Views: 114

### Re: Atomic Spectra pre-module quiz

I'm not quite sure of the difference between atomic absorption vs. atomic emission spectroscopy, but I do know that the lines on the spectrum represent the different energy levels that the electron can be on.
Sat Oct 20, 2018 9:18 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: HW problem 1.43
Replies: 1
Views: 58

### Re: HW problem 1.43

I believe just the drawing of the box is sufficient. But, you could include the wavelength of the electron if you want to.
Sat Oct 20, 2018 9:17 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Coulomb's Law
Replies: 3
Views: 131

### Re: Coulomb's Law

I believe we discussed Coulomb's law mainly to demonstrate the effects of shielding on electrostatic attraction.
Sat Oct 13, 2018 5:08 pm
Forum: Properties of Light
Topic: Wavelength Units
Replies: 5
Views: 187

### Re: Wavelength Units

Using nanometers would be better for wavelength.
Sat Oct 13, 2018 5:01 pm
Forum: Properties of Electrons
Topic: Spectral Lines (Balmer Series & Lyman Series)
Replies: 3
Views: 103

### Re: Spectral Lines (Balmer Series & Lyman Series)

For me, it helps to draw the diagram that Lavelle draws in the lectures. This helps me visualize the electron going from its "excited" state to "resting" state and also the change in energy, which results in the release of photons.
Sat Oct 13, 2018 4:53 pm
Forum: DeBroglie Equation
Topic: WaveLike Properties
Replies: 3
Views: 99

### Re: WaveLike Properties

Technically, all matter has wave-like properties, but they can only be noticed in moving objects with small mass.
Fri Oct 05, 2018 10:57 am
Forum: General Science Questions
Topic: Common ions
Replies: 4
Views: 320

### Re: Common ions

Is there a list of all the common ions that we should know? I know a few but I'm not sure if there are more that I am missing.
Fri Oct 05, 2018 10:48 am
Forum: Limiting Reactant Calculations
Topic: Maximum Product Produced
Replies: 2
Views: 129

### Re: Maximum Product Produced

To determine maximum production, you need to know the number of moles of each reactant. The number of moles of the limiting reactant should determine maximum product via the molar ratio given. In this example, you would need more information in order to solve this question.
Fri Oct 05, 2018 10:42 am
Forum: Limiting Reactant Calculations
Topic: Compensating for Mole Ratios in Limiting Reactants
Replies: 3
Views: 162

### Re: Compensating for Mole Ratios in Limiting Reactants

Start by finding the number of moles of each reactant that you have. To do that, you need the molar mass, which can be found using the periodic table. After knowing how many moles of each reactant you have, compare these numbers to the molar ratio given in the equation to find out which particular m...